Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis

Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis Yanzhao He, Xiwen Luo, Mengwei Ding, Yuxiao Chen, Xuemei Tang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5659951/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Vitamin D deficiency is prevalent in children with juvenile idiopathic arthritis (JIA). Prevention and supplementation with vitamin D may help improve diseases. Understanding subtype-specific variations in vitamin D levels before initiating treatment could provide valuable insights for early monitoring. Methods This study included 236 newly diagnosed, untreated children with active JIA who were admitted to Chongqing Medical University Children's Hospital between May 2019 and April 2024. Demographic and clinical characteristics, inflammatory markers, vitamin D levels, bone metabolism, and bone mineral density were retrospectively reviewed. Univariable and multivariable analyses were performed to identify factors affecting vitamin D levels and assess intergroup differences among JIA subtypes. Results Univariable analysis showed positive correlations of calcium and phosphorus levels with vitamin D levels, while body weight, body mass index, normalized erythrocyte sedimentation rate (ESR), and IL-6 exhibited negative correlations ( p < 0.05). Multivariable analysis identified reduced bone mineral density, normalized ESR, and normalized C-reactive protein (CRP) as significant variables associated with vitamin D levels. The stratified analysis revealed notable differences in gender, weight, and bone density across JIA subtypes. Conclusion Vitamin D deficiency is associated with inflammation in JIA. Findings from the multivariate generalized linear regression model emphasize the distinct patterns of vitamin D levels and their influencing factors across JIA subtypes, offering critical insights for early monitoring and informed clinical decision-making before treatment. Trial registration The study was registered on chictr.org.cn on June 12, 2022 (ID: ChiCTR2200060798). Juvenile idiopathic arthritis Vitamin D Disease onset Inflammation Figures Figure 1 Figure 2 Figure 3 Introduction Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease in childhood starting before 16 years old. The prevalence of JIA varies between 16 and 150 per 100,000 people [ 1 ]. The main diagnostic criteria used are the 2001 International League Against Rheumatology (ILAR) classification and the 2018 Pediatric Rheumatology International Trials Organization (PRINTO) classification [ 2 , 3 ]. The cause of JIA is not fully understood, and multiple factors such as genetics, environment, infection, and immunity are involved in the development of JIA. Treatment of JIA includes drug therapy such as non-steroidal anti-inflammatory drugs (NSAIDs), disease-modifying anti-rheumatic drugs (DMARDs), glucocorticoids, and physical therapy, etc. Despite the effectiveness of the current treatment strategies, some patients with JIA may still develop a prolonged course and poor outcome, with symptoms persisting into adulthood, accompanied by different comorbidities, and with a high rate of disability [ 4 ]. Vitamin D is one of the regulators of the innate and adaptive immune system [ 5 , 6 ]. Innate immune cells like neutrophils, macrophages, and monocytes can be activated and differentiated by vitamin D, which also has anti-inflammatory and immunomodulatory effects. Additionally, vitamin D plays a role in controlling T cell immunodeficiency and adaptive immunity. T cells that are persistently active in immune-mediated illnesses release inflammatory cytokines. When the vitamin D level decreases, it may reduce the ability to activate and shut down T cells, resulting in T-cell immune imbalance [ 7 ]. Many studies have suggested that vitamin D supplementation might be beneficial to reducing inflammation and immune cell proliferation and improving clinical symptoms in rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and ankylosing spondylitis (AS) [ 8 , 9 ]. Low vitamin D concentration is associated with increased pro-inflammatory mediators and disease activity. Hence, the appropriate prevention and treatment of vitamin D deficiency is significant in rheumatic diseases [ 10 ]. In addition, vitamin D regulates calcium (Ca) and phosphorus (P) balance in bone by promoting intestinal absorption of Ca and P, increasing renal reabsorption of Ca, and regulating the activity of skeletal cells to maintain bone health [ 11 ]. It is related to the increase of bone mineral density (BMD) and the prevention of osteoporosis and fracture, which is also important for patients with rheumatic diseases who are receiving long-term glucocorticoid therapy [ 11 , 12 ]. Therefore, maintaining vitamin D levels is of great significance for patients with chronic arthritis. Vitamin D deficiency is common in children with JIA. Studies have reported that prolonged exposure to the inflammatory state and medication may affect vitamin D levels in JIA patients [ 10 ]. The existing research strategies for vitamin D and JIA are different. Two studies indicated that patients with JIA had significantly lower levels of vitamin D than healthy children [ 18 , 19 ]. RA-related in-vitro experiments have confirmed that 1,25(OH)2D3 promotes the differentiation of T helper (Th) cells from Th1/Th17 to Th2, inhibits the production of B cells and autoantibodies, and reduces the release of pro-inflammatory cytokines by macrophages, such as IL-1β, IL-17, IL-6, and TNF-α, thereby suppressing synovial cell proliferation [ 21 – 23 ]. JIA encompasses both inherent and adaptive immune characteristics, suggesting a close relationship between vitamin D deficiency and immune regulation in JIA patients exhibiting more severe disease characteristics. However, due to the differences in population, geographical region, disease characteristics, disease status, etc., there are contradictions among these results [ 13 ]. Hence, we conducted this retrospective study by including untreated newly diagnosed JIA patients to explore the relationship between vitamin D levels and JIA subtypes at the early stages of the disease, and to provide a theoretical basis for clinical guidance on vitamin D monitoring and treatment supplementation. Methods Study design and populations We conducted a retrospective study and enrolled 236 newly diagnosed and untreated patients with active JIA who were admitted to the Children’s Hospital of Chongqing Medical University. These patients were diagnosed by more than two rheumatologists according to the ILAR or PRINTO classification criteria from May 2019 to April 2024. All included patients had complete clinical data. Twelve children who did not match the diagnostic criteria, had missing information, or were lost to visits were excluded (Fig. 1 ). General and clinical information and assessment of vitamin D levels General information included age, gender, and ethnicity. Clinical information consisted of height, body weight, body mass index (BMI), diagnosis, and the season of testing. Vitamin D levels were measured using the Siemens AD-VIA Centaur XP fully automated electrochemiluminescence immunoassay analyzer. The levels of vitamin D were categorized as follows, (i) ≤ 10 ng/mL as severe Vitamin D deficiency, (ii) 10–20 ng/mL as Vitamin D deficiency, (iii) 20–30 ng/mL as Vitamin D insufficiency, and (iv) ≥ 30 ng/mL as normal Vitamin D [ 14 ]. To assess disease activity, we also measured pre-treatment ESR, CRP, cytokines (interleukin (IL)-10, TNF-α, IL-1β, IFN-γ, IL-6, IL-17A, IL-8, IL-4, IL-2), rheumatoid factor (RF), anti-cyclic citrullinated antibodies (anti-CCP), anti-nuclear antibodies (ANA), Ca, P, and alkaline phosphatase (ALP), and refined BMD examination to assess whether the patient present with reduced bone mass. Besides, the ESR or CRP was normalized to a 0 to 10 scale [ 15 ]. All the information gathered at the first diagnosis was considered baseline information. Furthermore, we confirmed the final JIA diagnosis by the recent follow-up. Statistical analysis The Shapiro-Wilk test was utilized to evaluate the normality of the data distribution. Normally distributed continuous variables were described with mean and standard deviation (SD), while non-normal continuous variables were depicted by median and inter-quartile range (IQR). Differences among the groups were analyzed by using one-way ANOVA to determine the factors that may affect vitamin D levels in children with JIA. Multivariable generalized linear regression analysis was used to judge the correlation between vitamin D levels and JIA and to estimate the influence of different factors affecting whether vitamin D was deficient in JIA patients at the first diagnosis. Stepwise regression adopts the forward selection strategy to test JIA characteristic indicators, bone metabolism-related indicators, sociodemographic characteristics, and cytokines. The multivariable regression model showed significant differences in vitamin D levels among subgroups of JIA in terms of gender, weight, and bone mass reduction. To evaluate the relationship between vitamin D levels in each subtype of JIA and these variables, we conducted stratified analyses based on three variables. By interacting with gender, weight, and bone mass reduction, we further determined whether the interaction between different variables was statistically significant. We used R language (version 4.3.3) for statistical analysis and data visualization. Coefficients and 95% confidence intervals (CI) were calculated to assess the associations. A two-sided p- value < 0.05 was set as statistically significant. Results General information of participants We first searched and found 488 children diagnosed with JIA who had undergone vitamin D testing in the Database of the Department of Rheumatology and Immunology of Children’s Hospital of Chongqing Medical University. After reviewing the electronic clinical records of 488 pediatric patients, 248 individuals were screened for simultaneous detection of CRP, ESR, RF, ANA, cytokines, and liver function indicators. 12 incomplete cases were excluded from verification by two rheumatologists. Finally, 236 patients with JIA were eligible, and the effective inclusion rate was around 96.15%. Table 1 and Table 2 show the baseline characteristics of 236 pediatric patients. Male patients (56.36%) were more common, with Han patients being the majority (87.29%). The mean age was 108.87 ± 49.37 months. The mean body weight was 31.51 ± 15.93 kilograms (kg). According to the growth curve of children in China, the weight level of children at different ages was evaluated, with the highest proportion being normal weight (84.68%) [ 16 , 17 ]. The average BMI of 138 children with JIA was 17.30 ± 3.87 (kg/m²). According to the ILAR classification criteria, the confirmed diagnosis at the last follow-up showed that the proportion of JIA diagnoses was oligoarticular JIA (oJIA) (11.02%), systemic JIA (sJIA) (10.17%), RF-positive polyarticular JIA (pJIA) (7.63%), RF-negative pJIA (17.37%), enthesitis-related arthritis (ERA) (27.54%), and undifferentiated JIA (26.27%), respectively (Table 2 and Supplementary Fig. 1). In patients with ANA positive (22.84%, 53/232), 26.42% (14/53) were undifferentiated JIA, and 20.75% (11/53) were oJIA. 8.09% (19/235) of JIA patients were anti-CCP positive, of which 89.47% (17/19) were RF-positive pJIA patients, and 10.53% (2/19) were undifferentiated JIA patients. The mean ESR of all patients was 36.57 ± 31.92 mm/1hr and the mean CRP was 23.91 ± 30.10 mg/L. Additionally, the mean level of IL-6, 69.07 ± 288.24 pg/ml, was higher (Table 2 and Supplementary Table 1). Most patients in this cohort were initially diagnosed in the spring (33.47%), followed by the summer (30.08%). The mean vitamin D level of 236 patients was 21.23 ± 9.09 ng/ml. There were more children with vitamin D deficiency levels (41.53%) and vitamin D insufficiency levels (35.17%). We further evaluated the vitamin D levels in each JIA subgroup. The data demonstrated more vitamin D deficiency cases in ERA, RF-negative pJIA, and RF-positive pJIA groups, mainly located at the deficiency level. Ca, P, and ALP were mostly within the normal reference range, accounting for 97.41%, 99.57%, and 89.66%, respectively. BMD examination revealed a decrease in bone mass in 69 (29.24%) children with JIA (Table 2 and Supplementary Table 1). We further explored whether there were differences in vitamin D levels among children with different JIA subtypes (Supplementary Fig. 2). By consulting literature to understand the relevant factors that may affect vitamin D levels, combining relevant indicators in clinical diagnosis and treatment that may affect JIA diagnosis and reflect the inflammatory status of the disease, and considering the potential interaction between confounding factors, we conducted univariable analysis on JIA classification and related covariates that may affect vitamin D levels or JIA disease status. Figure 2 shows that the vitamin D levels in the sJIA group were lower than those in other groups, with significantly higher levels in the oJIA group ( p = 0.025) and undifferentiated JIA group ( p = 0.005) compared to the sJIA group. The estimated beta (95% CI) were 0.68 (0.10, 1.29) and 0.75 (0.24, 1.31), respectively. In addition, weight at the upper middle level, weight at the overweight level, BMI, normalized erythrocyte sedimentation rate, and elevated IL-6 hurt vitamin D levels. Instead, Ca and P levels have a positive impact on vitamin D levels ( p < 0.05). Furthermore, the vitamin D levels of JIA patients measured during winter are significantly higher than those measured in other seasons. Gender, ethnicity, age, height, weight, tri-class weight, rheumatoid factor, anti-CCP, ANA, normalized CRP, IL-10 level, TNF-α Horizontal, IL-1 β There was no statistically significant difference ( p > 0.05) in the effects of levels of vitamin D, IFN, IL-17A, IL-4, IL-2, ALP, and decreased bone density. Multifactorial analysis revealed the differences in vitamin D levels among JIA subtypes Model 1 (univariable analysis) compared the differences in vitamin D levels between JIA groups, and the results showed that the vitamin D levels in the ERA group, oJIA group, RF-negative pJIA group, and undifferentiated JIA group were higher than those in the sJIA group, with estimated coefficients (95% CI) of 0.14 (-0.39,0.71), 0.68 (0.10,1.29), 0.53 (-0.02,1.11), and 0.75 (0.24,1.31), respectively. Then in Model 2, age and gender were included. Model 3 incorporated three categories of body weight and surface area. Anti-CCP, ANA, normalized erythrocyte sedimentation rate, and CRP were added in Model 4. Finally, Model 5 included Ca, P, ALP, and bone density. The final estimated coefficients (95% CI) for the four groups were 0.66 (0.03, 1.31), 0.69 (0.02, 1.38), 0.70 (0.10, 1.32), and 0.77 (0.19, 1.39). The last model showed that the vitamin D levels in the patients with ERA, oJIA, RF-negative pJIA, and undifferentiated JIA were higher than those in the sJIA, and the differences were statistically significant ( p < 0.05). On the contrary, although the vitamin D levels in the group of RF-positive pJIA were higher than those in the sJIA, the evaluation coefficients on Model 1 to 5 showed 0.08 (-0.55,0.73), 0.28 (-0.34,0.91), 0.23 (-0.39,0.87), 0.44 (-0.47,1.32), and 0.38 (-0.50,1.24), respectively, with no statistically significant difference ( p > 0.05). It is worth noting that in Model 5, normalized ESR, normalized CRP, and decreased bone mineral density may be risk factors affecting vitamin D levels, and the differences were statistically significant ( p < 0.05) (Table 3). Stratified analysis showed the influence of multiple factors on vitamin D levels Before conducting the stratified analysis, we assessed the interaction between JIA diagnosis and gender, weight, and bone mineral density and found a statistically significant interaction ( p < 0.05 for all) (Supplementary Table 2). Following, we performed the stratified analysis in the fully adjusted model (Model 5) based on gender (male and female), weight (below, normal, above), and BMD (decreased and normal). The left side of Fig. 3 demonstrated that the impact of JIA diagnosis on vitamin D levels remained significant in women and individuals with normal weight. The data indicated that the vitamin D levels of female children with oJIA and undifferentiated JIA were notably higher than those with sJIA, and the effect of gender on vitamin D levels was more pronounced in women than in men. Additionally, children with normal body weight in ERA, oJIA, RF-negative pJIA, and undifferentiated JIA groups had significantly higher vitamin D levels than those in the sJIA group. There was no statistically significant difference in vitamin D levels between the RF-positive pJIA and sJIA groups. We also observed a negative correlation between overweight and vitamin D levels, while there was no statistically significant difference between the sJIA and non-sJIA groups. Therefore, JIA children with normal weight might be more conducive to stabilizing vitamin D levels. Discussion Juvenile idiopathic arthritis is a childhood-onset chronic rheumatic disease with complex etiology (genetic/environmental/immune factors) and variable outcomes, where current treatments often fail to prevent long-term disability. Vitamin D plays critical immunomodulatory roles by suppressing pro-inflammatory cytokines (e.g., IL-6, TNF α) and promoting immune balance while also maintaining bone health. In this retrospective study, we investigated the relationship between early active JIA in children and vitamin D levels and discovered that vitamin D deficiency or insufficiency was prevalent in JIA patients, consistent with previous research findings. These indicate that children with inflammatory arthritis have lower levels of circulating vitamin D concentration [ 18 , 19 , 13 ]. There were significant differences in vitamin D levels among different JIA subtypes. Our results showed that, in the early stages of active JIA, the vitamin D levels of sJIA are significantly lower than those of oJIA, RF-negative pJIA, ERA, and undifferentiated JIA, which is similar to the results reported by another study [ 18 ]. The vitamin D levels are higher in patients with RF-positive pJIA than those in sJIA without significant differences. A meta-analysis also indicated consistent results, but there was no significant difference in vitamin D levels between pJIA subgroups [ 20 ]. Therefore, we speculate that vitamin D might have a greater connection with sJIA and RF-positive pJIA patients [ 18 ]. There is no consensus on the relationship between vitamin D and disease activity. We observed a negative correlation between vitamin D levels and inflammatory markers IL-6 and ESR in children with JIA [ 24 , 25 , 13 , 26 ]. Many previous studies have also found that vitamin D may negatively influence disease inflammation of SLE, AS, psoriatic arthritis, Sjogren’s syndrome, and systemic sclerosis. Therefore, improving vitamin D deficiency in JIA patients with appropriate vitamin D supplementation may be helpful [ 13 , 27 ]. However, some studies have not found a correlation between insufficient vitamin D levels and active JIA or more severe disease characteristics [ 28 , 29 ]. Although numerous JIA studies have reported poor levels of vitamin D in JIA patients, the relationship between vitamin D and JIA remains controversial. Thorsen et al.’s work and a Mendel randomized study also revealed that there was no causal relationship between vitamin D level and JIA. Specific polymorphisms in the vitamin D family genes were associated with uveitis in patients with JIA, AS, and Behcet’s disease [ 30 ]. Unlike RA, there is no specific relationship between vitamin D receptor polymorphism and the development of SLE, and there may not be a causal relationship with AS [ 24 , 27 ]. The above indicates that the mechanism of vitamin D regulating immune response has high heterogeneity in distinct diseases. Through interactive-stratified analysis, we found that gender had a considerable impact on the vitamin D status of JIA patients. Specifically, the vitamin D levels of female patients with oJIA and undifferentiated JIA were significantly higher than those with sJIA, but one study from Norway did not indicate any differences in vitamin D levels between genders [ 29 ]. There are also differences in the correlation between gender and vitamin D deficiency in the population. The study by Song et al. demonstrated that in China, the average vitamin D level of women tends to be lower than that of men [ 23 ]. Studies from other countries have reported a significantly higher proportion of vitamin D deficiency in girls compared to boys [ 31 ], and lower levels of vitamin D in female patients with Sjogren’s syndrome compared to the control group [ 10 ]. Some opposite findings have shown that the prevalence of vitamin D deficiency is higher in male participants than in females [ 32 ]. In addition, a study in Türkiye observed that at the end of summer, women had a higher proportion of vitamin D deficiency, while at the end of winter, there was no significant correlation between gender and vitamin D levels [ 33 ]. These may be due to limited outdoor activities for women, clothing, and the use of sunscreen products, resulting in less sunlight exposure for women [ 34 ]. The outcomes might stem from the intricate interplay of factors influencing vitamin D levels. Moreover, our findings suggest that being overweight might be a risk factor for vitamin D deficiency in children with JIA. There was a significant correlation between obesity and increased involvement of lower limb joints in JIA patients at baseline, and obesity might have negative effects on the course and treatment of JIA [ 35 ], and the differences in dosage may lead to inadequate conventional administration in obese children [ 36 ]. The results of the meta-analysis indicated the inverse relationship between obesity indicators and vitamin D levels, but supplementing with vitamin D did not seem to reduce any obesity indicators, and more research is needed to elucidate the underlying pathophysiological mechanisms [ 37 ]. Interestingly, there were inconsistent results in our study regarding the relationship between decreased bone mineral density and vitamin D levels. Univariable analysis suggests a negative correlation between vitamin D levels and decreased BMD. Low bone mass is one of the complications of JIA, and serum vitamin D levels are significantly positively correlated with the Z-score of BMD. In JIA, osteoporosis is more pronounced in the femoral neck and bone compared to the lumbar spine [ 38 ]. Supplementation of vitamin D improved serum vitamin D levels in children with persistent active pJIA, but bone mineral density remained unchanged. On the other hand, supplementation of vitamin D significantly increased bone mineral density in JIA patients receiving systemic corticosteroid treatment, but the average bone mineral density rapidly decreased after discontinuing vitamin D supplementation [ 27 ]. On the contrary, our multivariable analyses showed biases in the positive and negative relationships between vitamin D levels and decreased BMD across different groups. The meta-analysis of the vitamin D test demonstrated that when baseline vitamin D > 40 nmol/L, there was no effect on bone mineral density or fracture risk [ 11 ]. The meta-analysis of vitamin D supplementation (not taken simultaneously with calcium) also found no effect in preventing fractures [ 39 ]. It is worth noting that studies have exposed that the combination of vitamin K and D can significantly improve total bone mineral density [ 40 ]. The interaction of genetic, hormonal, nutritional, immune, or pharmacological stimuli influences bone metabolism and homeostasis. Skeletal cell function, Ca and vitamin D homeostasis, sex hormone metabolism, and puberty simultaneously affect bone health. Thus, these contradictory findings are not convincing enough to support the benefits of high-dose vitamin D supplementation for bone health, and more comprehensive assessments are urgent for children with high risk of vitamin D deficiency in prevention, treatment, and follow-up processes [ 12 ]. So far, vitamin D deficiency and bone damage are still important issues during the growth and development of JIA. Nonetheless, the effectiveness of vitamin D supplements in preventing and treating diseases remains to be confirmed [ 10 , 18 ]. Marini F et al. found that the suboptimal status of vitamin D in JIA patients couldn’t be improved by vitamin D supplementation [ 41 ]. There are also studies indicating that MTX treatment can further reduce the concentration of vitamin D [ 28 ]. Considering the high incidence of vitamin D deficiency in JIA patients and the use of steroids, guidelines recommend providing 2–3 times the dose of vitamin D to children with rheumatic diseases receiving systemic steroid treatment [ 42 ]. However, a prospective randomized trial involving 42 JIA patients illustrated that supplementing with cholecalciferol (2000 IU/day) for 24 weeks could increase serum vitamin D levels in JIA patients without reducing disease activity or improving BMD [ 43 ]. Patients with severe JIA may need more supplements to maintain normal vitamin D levels. Studies with long-term observation and a larger sample are required to investigate the relationship between vitamin D levels and disease activity among JIA and its subtypes [ 18 , 44 ]. Our study fully considers the relationship between early JIA disease and vitamin D, the characteristics of JIA, and the relationship between inflammatory markers and vitamin D levels. However, serum vitamin D levels are subject to multiple confounding factors. Since vitamin D is primarily synthesized in the skin upon exposure to ultraviolet B (UVB) radiation [ 14 , 18 ], its levels vary considerably by geography and season, particularly in high-latitude regions where winter UVB exposure is insufficient [ 31 ]. The use of sunscreen and increased indoor activities in modern lifestyles further limit skin synthesis [ 42 ]. Insufficient consumption of foods rich in vitamin D, such as fish and dairy products, can lead to a decrease in vitamin D levels [ 5 , 14 ]. Given the research on the benefits of vitamin D supplementation during the previous COVID-19 pandemic, doctors now more frequently recommend consuming vitamin D-rich foods or supplements during seasons with insufficient sunlight exposure [ 45 , 46 ]. This may explain the univariable analysis finding that JIA patients tested in winter had higher serum vitamin D levels than those tested in other seasons, possibly due to non-iatrogenic interventions. Additionally, there are significant differences in dietary culture among different regions, which may partially explain the heterogeneity of vitamin D levels observed in various studies [ 9 ]. After strictly controlling for confounding factors, we found that the impact of JIA diagnostic features on vitamin D levels was insignificant. However, there was a significant negative correlation between inflammatory indicators and vitamin D levels, strongly suggesting the impact of inflammation on vitamin D. Moreover, individuals diagnosed with sJIA and RF-positive pJIA exhibited lower vitamin D levels compared to those with oJIA and undifferentiated JIA. This discrepancy could serve as a useful reference for rheumatologists in determining the necessity and timing of vitamin D supplementation for JIA patients. There were some limitations in this study. As a retrospective investigation, it primarily focused on baseline data from patients without dynamic follow-up, treatment, or vitamin D supplementation, and did not account for potential confounding factors that may influence vitamin D levels, such as sunlight exposure and dietary intake. Secondly, although the diagnostic season showed correlation with vitamin D levels, this association might be influenced by unmeasured factors, including geographical variations, UVB exposure, and metabolic differences. Future prospective studies are needed to establish optimal vitamin D therapeutic strategies and maintenance levels to enhance clinical management of vitamin D supplementation in JIA patients. Conclusion Our findings demonstrated that there were notable variations in vitamin D levels between the various JIA subtypes. In the early period of disease, active sJIA patients had significantly lower vitamin D levels than oJIA, RF-negative pJIA, ERA, and undifferentiated JIA patients. Conversely, patients with RF-positive pJIA had higher vitamin D levels than those in sJIA patients without significant differences. The substantial negative connection between vitamin D levels and inflammatory indicators implies the connection between vitamin D insufficiency and inflammation in JIA. We built a multivariable generalized linear regression model and found markedly lower vitamin D levels in untreated and new-onset sJIA patients, which provides pediatric physicians with clinical support for individualized treatment strategies for vitamin D in JIA [ 12 , 44 ]. Abbreviations Juvenile idiopathic arthritis (JIA), Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), International League Against Rheumatology (ILAR), Pediatric Rheumatology International Trials Organization (PRINTO), Rheumatoid arthritis (RA), Systemic lupus erythematosus (SLE), Ankylosing spondylitis (AS), Calcium (Ca), Phosphorus (P), Bone mineral density (BMD), Body mass index (BMI), Interleukin (IL), Rheumatoid factor (RF), Anti-cyclic citrullinated antibodies (anti-CCP), Anti-nuclear antibodies (ANA), Alkaline phosphatase (ALP), Standard deviation (SD), Inter-quartile range (IQR), Confidence intervals (CI), Kilograms (kg), Oligoarticular JIA (oJIA), Systemic JIA (sJIA), Polyarticular JIA (pJIA), Enthesitis-related arthritis (ERA), T helper (Th) cell. Declarations Ethical approval and consent to participant The study adhered to according to the ethical guidelines of the Helsinki Declaration and was approved by the Human Research Ethics Committee of the Children’s Hospital of Chongqing Medical University [the reference number of the ethical approval: 2022 (52)]. All data were captured through a retrospective review of the electronic medical records from the patient’s regular visits. Our study has already obtained the necessary informed consent from the participants’ parents or legal guardians of pediatric patients, including those younger than 16. Consent for publication Not applicable. Availability of data and materials The datasets generated and analysed during this study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing interests. Funding This work was supported by grants from the National Key R&D Program of China (No. 2021YFC2702003). Author contributions XM.T and XW.L designed the study. YZ.H and XW.L collected the data, and drafted the manuscript. YX.C assisted in data filtering. XW.L, MW.D, and YZ.H conducted the statistical analysis. XM.T reviewed and revised the manuscript. All authors have reviewed the manuscript and approved the final submission. Acknowledgments We are grateful to the patients and thank all the investigators who participated in the study. References Ravelli A, Martini A. Juvenile idiopathic arthritis. The Lancet 2007;369:767–78. https://doi.org/10.1016/S0140-6736(07)60363-8. Petty RE, Southwood TR, Manners P, Baum J, Glass DN, Goldenberg J, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. J Rheumatol 2004;31:390–2. Martini A, Ravelli A, Avcin T, Beresford MW, Burgos-Vargas R, Cuttica R, et al. 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Zong X-N, Li H. Construction of a new growth references for China based on urban Chinese children: comparison with the WHO growth standards. PloS One 2013;8:e59569. https://doi.org/10.1371/journal.pone.0059569. Stagi S, Bertini F, Cavalli L, Matucci-Cerinic M, Brandi ML, Falcini F. Determinants of vitamin D levels in children, adolescents, and young adults with juvenile idiopathic arthritis. J Rheumatol 2014;41:1884–92. https://doi.org/10.3899/jrheum.131421. Dağdeviren-Çakır A, Arvas A, Barut K, Gür E, Kasapçopur Ö. Serum vitamin D levels during activation and remission periods of patients with juvenile idiopathic arthritis and familial Mediterranean fever. Turk J Pediatr 2016;58:125–31. https://doi.org/10.24953/turkjped.2016.02.001. Nisar MK, Masood F, Cookson P, Sansome A, Östör AJ. What do we know about juvenile idiopathic arthritis and vitamin D? A systematic literature review and meta-analysis of current evidence. Clin Rheumatol 2013;32:729–34. https://doi.org/10.1007/s10067-012-2159-1. Chambers ES, Nanzer AM, Pfeffer PE, Richards DF, Timms PM, Martineau AR, et al. Distinct endotypes of steroid-resistant asthma characterized by IL-17Ahigh and IFN-γhigh immunophenotypes: Potential benefits of calcitriol. J Allergy Clin Immunol 2015;136:628-637. e4. https://doi.org/10.1016/j.jaci.2015.01.026. Kim H, Baek S, Hong S-M, Lee J, Jung SM, Lee J, et al. 1, 25-dihydroxy vitamin D3 and interleukin-6 blockade synergistically regulate rheumatoid arthritis by suppressing interleukin-17 production and osteoclastogenesis. J Korean Med Sci 2020;35. https://doi.org/10.3346/jkms.2020.35.e40. Song GG, Bae S-C, Lee YH. Association between vitamin D intake and the risk of rheumatoid arthritis: a meta-analysis. Clin Rheumatol 2012;31:1733–9. https://doi.org/10.1007/s10067-012-2080-7. Bouaddi I, Rostom S, El Badri D, Hassani A, Chkirate B, Abouqal R, et al. Vitamin D concentrations and disease activity in Moroccan children with juvenile idiopathic arthritis. BMC Musculoskelet Disord 2014;15:1–5. https://doi.org/10.1186/1471-2474-15-115. Çomak E, Doğan ÇS, Uslu-Gökçeoğlu A, Akbaş H, Özdem S, Koyun M, et al. Association between vitamin D deficiency and disease activity in juvenile idiopathic arthritis. Turk J Pediatr 2014;56:626–31. Nandi M, Mullick MAS, Nandy A, Samanta M, Sarkar S, Sabui TK. Evaluation of vitamin D profile in juvenile idiopathic arthritis. Mod Rheumatol 2022;32:792–6. https://doi.org/10.1093/mr/roab053. Wu C-Y, Yang H-Y, Luo S-F, Huang J-L, Lai J-H. Vitamin d supplementation in patients with juvenile idiopathic arthritis. Nutrients 2022;14:1538. https://doi.org/10.3390/nu14081538. Stawicki MK, Abramowicz P, Góralczyk A, Młyńczyk J, Kondratiuk A, Konstantynowicz J. Prevalence of vitamin D deficiency in patients treated for juvenile idiopathic arthritis and potential role of methotrexate: a preliminary study. Nutrients 2022;14:1645. https://doi.org/10.3390/nu14081645. Cetrelli L, Bletsa A, Lundestad A, Gil EG, Fischer J, Halbig J, et al. Vitamin D, oral health, and disease characteristics in juvenile idiopathic arthritis: a multicenter cross-sectional study. BMC Oral Health 2022;22:333. https://doi.org/10.1186/s12903-022-02349-1. Pillar S, Amer R. The association between vitamin D and uveitis: A comprehensive review. Surv Ophthalmol 2022;67:321–30. https://doi.org/10.1016/j.survophthal.2021.07.006. Isa H, Almaliki M, Alsabea A, Mohamed A. Vitamin D deficiency in healthy children in Bahrain: do gender and age matter? East Mediterr Health J 2020;26:260–7. https://doi.org/10.26719/emhj.19.084. AlQuaiz AM, Kazi A, Fouda M, Alyousefi N. Age and gender differences in the prevalence and correlates of vitamin D deficiency. Arch Osteoporos 2018;13:1–11. https://doi.org/10.1007/s11657-018-0461-5. Erol M, Yiğit Ö, Küçük SH, Bostan Gayret Ö. Vitamin D Deficiency in Children and Adolescents in Bağcılar, İstanbul. J Clin Res Pediatr Endocrinol 2015;7:134–9. https://doi.org/10.4274/jcrpe.1888. Al Shaikh AM, Abaalkhail B, Soliman A, Kaddam I, Aseri K, Al Saleh Y, et al. Prevalence of Vitamin D Deficiency and Calcium Homeostasis in Saudi Children. J Clin Res Pediatr Endocrinol 2016;8:461–7. https://doi.org/10.4274/jcrpe.3301. Giani T, De Masi S, Maccora I, Tirelli F, Simonini G, Falconi M, et al. The influence of overweight and obesity on treatment response in juvenile idiopathic arthritis. Front Pharmacol 2019;10:637. https://doi.org/10.3389/fphar.2019.00637. Balevic SJ, Becker ML, Gonzalez D, Funk RS. Low etanercept concentrations in children with obesity and juvenile idiopathic arthritis. J Pediatr Pharmacol Ther 2021;26:809–14. https://doi.org/10.5863/1551-6776-26.8.809. Karampela I, Sakelliou A, Vallianou N, Christodoulatos G-S, Magkos F, Dalamaga M. Vitamin D and obesity: current evidence and controversies. Curr Obes Rep 2021;10:162–80. https://doi.org/10.1007/s13679-021-00433-1. Charuvanij S, Malakorn H, Densupsoontorn N, Nakavachara P. Bone Mineral density and serum 25OHD in children and adolescents with juvenile idiopathic arthritis. Clin Pediatr (Phila) 2023;62:456–65. https://doi.org/10.1177/00099228221136982. Reid IR, Bolland MJ, Grey A. Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysis. The Lancet 2014;383:146–55. Kuang X, Liu C, Guo X, Li K, Deng Q, Li D. The combination effect of vitamin K and vitamin D on human bone quality: A meta-analysis of randomized controlled trials. Food Funct 2020;11:3280–97. https://doi.org/10.1039/C9FO03063H. Marini F, Falcini F, Stagi S, Fabbri S, Ciuffi S, Rigante D, et al. Study of vitamin D status and vitamin D receptor polymorphisms in a cohort of Italian patients with juvenile idiopathic arthritis. Sci Rep 2020;10:17550. https://doi.org/10.1038/s41598-020-74861-9. Gröber U, Spitz J, Reichrath J, Kisters K, Holick MF. Vitamin D: update 2013: from rickets prophylaxis to general preventive healthcare. Dermatoendocrinol 2013;5:331–47. https://doi.org/10.4161/derm.26738. Tang T, Zhang Y, Luo C, Liu M, Xu L, Tang X. Adjunctive vitamin D for the treatment of active juvenile idiopathic arthritis: An open‑label, prospective, randomized controlled trial. Exp Ther Med 2019;18:4921–6. Stawicki MK, Abramowicz P, Sokolowska G, Wołejszo S, Grant WB, Konstantynowicz J. Can vitamin D be an adjuvant therapy for juvenile rheumatic diseases? Rheumatol Int 2023;43:1993–2009. https://doi.org/10.1007/s00296-023-05411-5. Ferder L, Martín Giménez VM, Inserra F, et al. Vitamin D supplementation as a rational pharmacological approach in the COVID-19 pandemic. Am J Physiol Lung Cell Mol Physiol. 2020;319(6):L941-L948. doi:10.1152/ajplung.00186.2020 Kopeček M, Höschl C. Season of the year, vitamin D and COVID-19. Roční období, vitamin D a COVID-19. Cas Lek Cesk. 2020;159(7-8):312-316. Tables Tables 1 to 3 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Table1.xlsx Table 1. General information of 236 patients. Table2.xlsx Table 2. Clinical information of 236 patients. Table3.xlsx Table 3.Multivariable analysis of the association between vitamin D and JIA. SupplementaryTable1.xlsx Supplementary Figure 1. Change of JIA classification from the first diagnose to the recent follow-up ILAR, International League of Associations for Rheumatology; JIA, juvenile idiopathic arthritis SupplementaryTable2.xlsx Supplementary Figure 2. Vitamin D levels and distribution in different JIA subgroups JIA, juvenile idiopathic arthritis; VD, vitamin D. SupplementaryTable3.xlsx SupplementaryFigure1.pdf SupplementaryFigure2.pdf Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5659951","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":449214198,"identity":"2bb73696-5cd0-49ed-aee0-b5f3c357df7d","order_by":0,"name":"Yanzhao He","email":"","orcid":"","institution":"Chongqing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yanzhao","middleName":"","lastName":"He","suffix":""},{"id":449214199,"identity":"9dd0a73a-9ff2-4c4d-ade2-225873256449","order_by":1,"name":"Xiwen Luo","email":"","orcid":"","institution":"Children's Hospital of Chongqing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Xiwen","middleName":"","lastName":"Luo","suffix":""},{"id":449214200,"identity":"9442703e-1fe6-4c6e-8190-08a79753f288","order_by":2,"name":"Mengwei Ding","email":"","orcid":"","institution":"Children's Hospital of Chongqing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Mengwei","middleName":"","lastName":"Ding","suffix":""},{"id":449214201,"identity":"9a210dc6-aba8-4f10-8308-2c6b03249467","order_by":3,"name":"Yuxiao Chen","email":"","orcid":"","institution":"Children's Hospital of Chongqing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yuxiao","middleName":"","lastName":"Chen","suffix":""},{"id":449214202,"identity":"5c98cf71-893d-4efb-8348-27d94b3b3bde","order_by":4,"name":"Xuemei Tang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIie2RvWrDMBRGJS7YyzVaY9yHUDG4BEzyIFkcAp6sjiWjwKDVq/0WmbpWQZApTdZCluzNINMHaLUVOigZA9UZL9/h/hESCNw1AFpX6xIZk/4g/irR8mz39UPa61sVgvnjoEzJZeVX5vG7+UxUuWAxKTLcH5ETTe3YeLrgcz0dVC2GltQZrk/4BBLS4dU3WFPwURmxMWTnupxwKnUEiU9hl4Iv1bd4M1RliTog19UVZdLk51FpsQEAt76+Qfm4FLQ/rERvIuqOvMK037beXeKuyb/wZSa67mjdK2dzxtqtHT2KI5r8KVDpzTvAXksEAoHAP+cHVwNT1rHx46UAAAAASUVORK5CYII=","orcid":"","institution":"Children's Hospital of Chongqing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Xuemei","middleName":"","lastName":"Tang","suffix":""}],"badges":[],"createdAt":"2024-12-17 08:53:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5659951/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5659951/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82065660,"identity":"d07f07d2-839c-4dfb-a7d9-43492e127a49","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2751708,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart of the study\u003c/p\u003e\n\u003cp\u003eJIA, juvenile idiopathic arthritis; ILAR, International League of Associations for Rheumatology; RF, rheumatoid factor.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/ac934cda17ef764ce054fdce.png"},{"id":82067217,"identity":"096d86ed-0be6-4362-9878-79d8438ab02f","added_by":"auto","created_at":"2025-05-06 12:43:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":56297,"visible":true,"origin":"","legend":"\u003cp\u003eUnivariable analysis of the association between vitamin D and JIA\u003c/p\u003e\n\u003cp\u003eJIA, juvenile idiopathic arthritis; 3f means three classifications of body weight; 5f means five classifications of body weight; 9f means nine classifications of body weight; BMI, body mass index; BSA, body surface area; BMD, bone mineral density; RF, rheumatoid factor; anti-CCP, anti-cyclic citrullinated antibodies; ANA, anti-nuclear antibody; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; IL, interleukin; TNF, tumor necrosis factor; Ca, calcium; P, phosphorus; ALP, alkaline phosphatase.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/2f454a84d8745be324f2990c.png"},{"id":82065656,"identity":"323738aa-419a-4854-a6c7-4c97b6526165","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":21566,"visible":true,"origin":"","legend":"\u003cp\u003eStratified analysis of the association between gender, weight, BMD and JIA respectively\u003c/p\u003e\n\u003cp\u003eJIA, juvenile idiopathic arthritis.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/4d8930afd0e8c6c5a01f69a6.png"},{"id":85733816,"identity":"d79efb74-972b-460b-b4ce-986df229912b","added_by":"auto","created_at":"2025-07-01 07:47:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3527536,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/318b0673-8cba-4b7a-98e4-51e9a0725b54.pdf"},{"id":82067746,"identity":"aa862f88-0934-4d3b-9f49-fb114f22e5a9","added_by":"auto","created_at":"2025-05-06 12:51:31","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":10856,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e General information of 236 patients.\u003c/p\u003e","description":"","filename":"Table1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/088ece44a98d597ed22a19f5.xlsx"},{"id":82065665,"identity":"9ce23b22-1d7b-4a3e-a320-7b81db240a17","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":11422,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTable 2. \u003c/strong\u003eClinical information of 236 patients.\u003c/p\u003e","description":"","filename":"Table2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/afaac20f29821a35e115a6fa.xlsx"},{"id":82065661,"identity":"b8c814d5-3521-4ea1-85b0-f30655652ce0","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"xlsx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":14104,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003eMultivariable analysis of the association between vitamin D and JIA.\u003c/p\u003e","description":"","filename":"Table3.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/e18512498033ebb4b703d1f3.xlsx"},{"id":82065667,"identity":"cc5911e9-7085-44d8-8589-55bfdf218467","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"xlsx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":21522,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSupplementary Figure 1. \u003c/strong\u003eChange of JIA classification from the first diagnose to the recent follow-up\u003c/p\u003e\n\u003cp\u003eILAR, International League of Associations for Rheumatology; JIA, juvenile idiopathic arthritis\u003c/p\u003e","description":"","filename":"SupplementaryTable1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/89d8251032997d0e11bee61e.xlsx"},{"id":82067222,"identity":"81fb247f-675c-4515-97ee-7528729c4e0e","added_by":"auto","created_at":"2025-05-06 12:43:31","extension":"xlsx","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":11008,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSupplementary Figure 2. \u003c/strong\u003eVitamin D levels and distribution in different JIA subgroups\u003c/p\u003e\n\u003cp\u003eJIA, juvenile idiopathic arthritis; VD, vitamin D.\u003c/p\u003e","description":"","filename":"SupplementaryTable2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/e806319a9975f8ab23d7b0e3.xlsx"},{"id":82067221,"identity":"ad346e13-a72a-472e-940e-ea35f30a0d64","added_by":"auto","created_at":"2025-05-06 12:43:31","extension":"xlsx","order_by":6,"title":"","display":"","copyAsset":false,"role":"supplement","size":11340,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTable3.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/d78df6aa093566d0183539bb.xlsx"},{"id":82067226,"identity":"40843c49-2295-49fa-964c-ca8b712c4b37","added_by":"auto","created_at":"2025-05-06 12:43:31","extension":"pdf","order_by":7,"title":"","display":"","copyAsset":false,"role":"supplement","size":244661,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFigure1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/d595fea6babcf722b4001cb3.pdf"},{"id":82065674,"identity":"9a0b1f94-bfc9-4aae-bdc5-55e06484811c","added_by":"auto","created_at":"2025-05-06 12:35:31","extension":"pdf","order_by":8,"title":"","display":"","copyAsset":false,"role":"supplement","size":4575936,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFigure2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5659951/v1/67c5efb146caa62529524cc3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eJuvenile idiopathic arthritis (JIA) is a chronic rheumatic disease in childhood starting before 16 years old. The prevalence of JIA varies between 16 and 150 per 100,000 people [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The main diagnostic criteria used are the 2001 International League Against Rheumatology (ILAR) classification and the 2018 Pediatric Rheumatology International Trials Organization (PRINTO) classification [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The cause of JIA is not fully understood, and multiple factors such as genetics, environment, infection, and immunity are involved in the development of JIA. Treatment of JIA includes drug therapy such as non-steroidal anti-inflammatory drugs (NSAIDs), disease-modifying anti-rheumatic drugs (DMARDs), glucocorticoids, and physical therapy, etc. Despite the effectiveness of the current treatment strategies, some patients with JIA may still develop a prolonged course and poor outcome, with symptoms persisting into adulthood, accompanied by different comorbidities, and with a high rate of disability [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eVitamin D is one of the regulators of the innate and adaptive immune system [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Innate immune cells like neutrophils, macrophages, and monocytes can be activated and differentiated by vitamin D, which also has anti-inflammatory and immunomodulatory effects. Additionally, vitamin D plays a role in controlling T cell immunodeficiency and adaptive immunity. T cells that are persistently active in immune-mediated illnesses release inflammatory cytokines. When the vitamin D level decreases, it may reduce the ability to activate and shut down T cells, resulting in T-cell immune imbalance [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Many studies have suggested that vitamin D supplementation might be beneficial to reducing inflammation and immune cell proliferation and improving clinical symptoms in rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and ankylosing spondylitis (AS) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Low vitamin D concentration is associated with increased pro-inflammatory mediators and disease activity. Hence, the appropriate prevention and treatment of vitamin D deficiency is significant in rheumatic diseases [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition, vitamin D regulates calcium (Ca) and phosphorus (P) balance in bone by promoting intestinal absorption of Ca and P, increasing renal reabsorption of Ca, and regulating the activity of skeletal cells to maintain bone health [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It is related to the increase of bone mineral density (BMD) and the prevention of osteoporosis and fracture, which is also important for patients with rheumatic diseases who are receiving long-term glucocorticoid therapy [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Therefore, maintaining vitamin D levels is of great significance for patients with chronic arthritis.\u003c/p\u003e \u003cp\u003eVitamin D deficiency is common in children with JIA. Studies have reported that prolonged exposure to the inflammatory state and medication may affect vitamin D levels in JIA patients [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The existing research strategies for vitamin D and JIA are different. Two studies indicated that patients with JIA had significantly lower levels of vitamin D than healthy children [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. RA-related in-vitro experiments have confirmed that 1,25(OH)2D3 promotes the differentiation of T helper (Th) cells from Th1/Th17 to Th2, inhibits the production of B cells and autoantibodies, and reduces the release of pro-inflammatory cytokines by macrophages, such as IL-1β, IL-17, IL-6, and TNF-α, thereby suppressing synovial cell proliferation [\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. JIA encompasses both inherent and adaptive immune characteristics, suggesting a close relationship between vitamin D deficiency and immune regulation in JIA patients exhibiting more severe disease characteristics. However, due to the differences in population, geographical region, disease characteristics, disease status, etc., there are contradictions among these results [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Hence, we conducted this retrospective study by including untreated newly diagnosed JIA patients to explore the relationship between vitamin D levels and JIA subtypes at the early stages of the disease, and to provide a theoretical basis for clinical guidance on vitamin D monitoring and treatment supplementation.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and populations\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective study and enrolled 236 newly diagnosed and untreated patients with active JIA who were admitted to the Children\u0026rsquo;s Hospital of Chongqing Medical University. These patients were diagnosed by more than two rheumatologists according to the ILAR or PRINTO classification criteria from May 2019 to April 2024. All included patients had complete clinical data. Twelve children who did not match the diagnostic criteria, had missing information, or were lost to visits were excluded (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eGeneral and clinical information and assessment of vitamin D levels\u003c/h3\u003e\n\u003cp\u003eGeneral information included age, gender, and ethnicity. Clinical information consisted of height, body weight, body mass index (BMI), diagnosis, and the season of testing.\u003c/p\u003e \u003cp\u003eVitamin D levels were measured using the Siemens AD-VIA Centaur XP fully automated electrochemiluminescence immunoassay analyzer. The levels of vitamin D were categorized as follows, (i)\u0026thinsp;\u0026le;\u0026thinsp;10 ng/mL as severe Vitamin D deficiency, (ii) 10\u0026ndash;20 ng/mL as Vitamin D deficiency, (iii) 20\u0026ndash;30 ng/mL as Vitamin D insufficiency, and (iv)\u0026thinsp;\u0026ge;\u0026thinsp;30 ng/mL as normal Vitamin D [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo assess disease activity, we also measured pre-treatment ESR, CRP, cytokines (interleukin (IL)-10, TNF-α, IL-1β, IFN-γ, IL-6, IL-17A, IL-8, IL-4, IL-2), rheumatoid factor (RF), anti-cyclic citrullinated antibodies (anti-CCP), anti-nuclear antibodies (ANA), Ca, P, and alkaline phosphatase (ALP), and refined BMD examination to assess whether the patient present with reduced bone mass. Besides, the ESR or CRP was normalized to a 0 to 10 scale [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. All the information gathered at the first diagnosis was considered baseline information. Furthermore, we confirmed the final JIA diagnosis by the recent follow-up.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe Shapiro-Wilk test was utilized to evaluate the normality of the data distribution. Normally distributed continuous variables were described with mean and standard deviation (SD), while non-normal continuous variables were depicted by median and inter-quartile range (IQR). Differences among the groups were analyzed by using one-way ANOVA to determine the factors that may affect vitamin D levels in children with JIA.\u003c/p\u003e \u003cp\u003eMultivariable generalized linear regression analysis was used to judge the correlation between vitamin D levels and JIA and to estimate the influence of different factors affecting whether vitamin D was deficient in JIA patients at the first diagnosis. Stepwise regression adopts the forward selection strategy to test JIA characteristic indicators, bone metabolism-related indicators, sociodemographic characteristics, and cytokines.\u003c/p\u003e \u003cp\u003eThe multivariable regression model showed significant differences in vitamin D levels among subgroups of JIA in terms of gender, weight, and bone mass reduction. To evaluate the relationship between vitamin D levels in each subtype of JIA and these variables, we conducted stratified analyses based on three variables. By interacting with gender, weight, and bone mass reduction, we further determined whether the interaction between different variables was statistically significant.\u003c/p\u003e \u003cp\u003eWe used R language (version 4.3.3) for statistical analysis and data visualization. Coefficients and 95% confidence intervals (CI) were calculated to assess the associations. A two-sided \u003cem\u003ep-\u003c/em\u003evalue\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was set as statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eGeneral information of participants\u003c/h2\u003e \u003cp\u003eWe first searched and found 488 children diagnosed with JIA who had undergone vitamin D testing in the Database of the Department of Rheumatology and Immunology of Children\u0026rsquo;s Hospital of Chongqing Medical University. After reviewing the electronic clinical records of 488 pediatric patients, 248 individuals were screened for simultaneous detection of CRP, ESR, RF, ANA, cytokines, and liver function indicators. 12 incomplete cases were excluded from verification by two rheumatologists. Finally, 236 patients with JIA were eligible, and the effective inclusion rate was around 96.15%.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;1 and Table\u0026nbsp;2 show the baseline characteristics of 236 pediatric patients. Male patients (56.36%) were more common, with Han patients being the majority (87.29%). The mean age was 108.87\u0026thinsp;\u0026plusmn;\u0026thinsp;49.37 months. The mean body weight was 31.51\u0026thinsp;\u0026plusmn;\u0026thinsp;15.93 kilograms (kg). According to the growth curve of children in China, the weight level of children at different ages was evaluated, with the highest proportion being normal weight (84.68%) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The average BMI of 138 children with JIA was 17.30\u0026thinsp;\u0026plusmn;\u0026thinsp;3.87 (kg/m\u0026sup2;).\u003c/p\u003e \u003cp\u003eAccording to the ILAR classification criteria, the confirmed diagnosis at the last follow-up showed that the proportion of JIA diagnoses was oligoarticular JIA (oJIA) (11.02%), systemic JIA (sJIA) (10.17%), RF-positive polyarticular JIA (pJIA) (7.63%), RF-negative pJIA (17.37%), enthesitis-related arthritis (ERA) (27.54%), and undifferentiated JIA (26.27%), respectively (Table\u0026nbsp;2 and Supplementary Fig.\u0026nbsp;1). In patients with ANA positive (22.84%, 53/232), 26.42% (14/53) were undifferentiated JIA, and 20.75% (11/53) were oJIA. 8.09% (19/235) of JIA patients were anti-CCP positive, of which 89.47% (17/19) were RF-positive pJIA patients, and 10.53% (2/19) were undifferentiated JIA patients. The mean ESR of all patients was 36.57\u0026thinsp;\u0026plusmn;\u0026thinsp;31.92 mm/1hr and the mean CRP was 23.91\u0026thinsp;\u0026plusmn;\u0026thinsp;30.10 mg/L. Additionally, the mean level of IL-6, 69.07\u0026thinsp;\u0026plusmn;\u0026thinsp;288.24 pg/ml, was higher (Table\u0026nbsp;2 and Supplementary Table\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eMost patients in this cohort were initially diagnosed in the spring (33.47%), followed by the summer (30.08%). The mean vitamin D level of 236 patients was 21.23\u0026thinsp;\u0026plusmn;\u0026thinsp;9.09 ng/ml. There were more children with vitamin D deficiency levels (41.53%) and vitamin D insufficiency levels (35.17%). We further evaluated the vitamin D levels in each JIA subgroup. The data demonstrated more vitamin D deficiency cases in ERA, RF-negative pJIA, and RF-positive pJIA groups, mainly located at the deficiency level. Ca, P, and ALP were mostly within the normal reference range, accounting for 97.41%, 99.57%, and 89.66%, respectively. BMD examination revealed a decrease in bone mass in 69 (29.24%) children with JIA (Table\u0026nbsp;2 and Supplementary Table\u0026nbsp;1).\u003c/p\u003e \u003cp\u003eWe further explored whether there were differences in vitamin D levels among children with different JIA subtypes (Supplementary Fig.\u0026nbsp;2). By consulting literature to understand the relevant factors that may affect vitamin D levels, combining relevant indicators in clinical diagnosis and treatment that may affect JIA diagnosis and reflect the inflammatory status of the disease, and considering the potential interaction between confounding factors, we conducted univariable analysis on JIA classification and related covariates that may affect vitamin D levels or JIA disease status. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows that the vitamin D levels in the sJIA group were lower than those in other groups, with significantly higher levels in the oJIA group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025) and undifferentiated JIA group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005) compared to the sJIA group. The estimated beta (95% CI) were 0.68 (0.10, 1.29) and 0.75 (0.24, 1.31), respectively. In addition, weight at the upper middle level, weight at the overweight level, BMI, normalized erythrocyte sedimentation rate, and elevated IL-6 hurt vitamin D levels. Instead, Ca and P levels have a positive impact on vitamin D levels (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Furthermore, the vitamin D levels of JIA patients measured during winter are significantly higher than those measured in other seasons. Gender, ethnicity, age, height, weight, tri-class weight, rheumatoid factor, anti-CCP, ANA, normalized CRP, IL-10 level, TNF-α Horizontal, IL-1 β There was no statistically significant difference (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) in the effects of levels of vitamin D, IFN, IL-17A, IL-4, IL-2, ALP, and decreased bone density.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMultifactorial analysis revealed the differences in vitamin D levels among JIA subtypes\u003c/h2\u003e \u003cp\u003eModel 1 (univariable analysis) compared the differences in vitamin D levels between JIA groups, and the results showed that the vitamin D levels in the ERA group, oJIA group, RF-negative pJIA group, and undifferentiated JIA group were higher than those in the sJIA group, with estimated coefficients (95% CI) of 0.14 (-0.39,0.71), 0.68 (0.10,1.29), 0.53 (-0.02,1.11), and 0.75 (0.24,1.31), respectively. Then in Model 2, age and gender were included. Model 3 incorporated three categories of body weight and surface area. Anti-CCP, ANA, normalized erythrocyte sedimentation rate, and CRP were added in Model 4. Finally, Model 5 included Ca, P, ALP, and bone density. The final estimated coefficients (95% CI) for the four groups were 0.66 (0.03, 1.31), 0.69 (0.02, 1.38), 0.70 (0.10, 1.32), and 0.77 (0.19, 1.39). The last model showed that the vitamin D levels in the patients with ERA, oJIA, RF-negative pJIA, and undifferentiated JIA were higher than those in the sJIA, and the differences were statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). On the contrary, although the vitamin D levels in the group of RF-positive pJIA were higher than those in the sJIA, the evaluation coefficients on Model 1 to 5 showed 0.08 (-0.55,0.73), 0.28 (-0.34,0.91), 0.23 (-0.39,0.87), 0.44 (-0.47,1.32), and 0.38 (-0.50,1.24), respectively, with no statistically significant difference (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). It is worth noting that in Model 5, normalized ESR, normalized CRP, and decreased bone mineral density may be risk factors affecting vitamin D levels, and the differences were statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;3).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStratified analysis showed the influence of multiple factors on vitamin D levels\u003c/h3\u003e\n\u003cp\u003eBefore conducting the stratified analysis, we assessed the interaction between JIA diagnosis and gender, weight, and bone mineral density and found a statistically significant interaction (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 for all) (Supplementary Table\u0026nbsp;2). Following, we performed the stratified analysis in the fully adjusted model (Model 5) based on gender (male and female), weight (below, normal, above), and BMD (decreased and normal). The left side of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrated that the impact of JIA diagnosis on vitamin D levels remained significant in women and individuals with normal weight. The data indicated that the vitamin D levels of female children with oJIA and undifferentiated JIA were notably higher than those with sJIA, and the effect of gender on vitamin D levels was more pronounced in women than in men. Additionally, children with normal body weight in ERA, oJIA, RF-negative pJIA, and undifferentiated JIA groups had significantly higher vitamin D levels than those in the sJIA group. There was no statistically significant difference in vitamin D levels between the RF-positive pJIA and sJIA groups. We also observed a negative correlation between overweight and vitamin D levels, while there was no statistically significant difference between the sJIA and non-sJIA groups. Therefore, JIA children with normal weight might be more conducive to stabilizing vitamin D levels.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eJuvenile idiopathic arthritis is a childhood-onset chronic rheumatic disease with complex etiology (genetic/environmental/immune factors) and variable outcomes, where current treatments often fail to prevent long-term disability. Vitamin D plays critical immunomodulatory roles by suppressing pro-inflammatory cytokines (e.g., IL-6, TNF α) and promoting immune balance while also maintaining bone health. In this retrospective study, we investigated the relationship between early active JIA in children and vitamin D levels and discovered that vitamin D deficiency or insufficiency was prevalent in JIA patients, consistent with previous research findings. These indicate that children with inflammatory arthritis have lower levels of circulating vitamin D concentration [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere were significant differences in vitamin D levels among different JIA subtypes. Our results showed that, in the early stages of active JIA, the vitamin D levels of sJIA are significantly lower than those of oJIA, RF-negative pJIA, ERA, and undifferentiated JIA, which is similar to the results reported by another study [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The vitamin D levels are higher in patients with RF-positive pJIA than those in sJIA without significant differences. A meta-analysis also indicated consistent results, but there was no significant difference in vitamin D levels between pJIA subgroups [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Therefore, we speculate that vitamin D might have a greater connection with sJIA and RF-positive pJIA patients [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere is no consensus on the relationship between vitamin D and disease activity. We observed a negative correlation between vitamin D levels and inflammatory markers IL-6 and ESR in children with JIA [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Many previous studies have also found that vitamin D may negatively influence disease inflammation of SLE, AS, psoriatic arthritis, Sjogren\u0026rsquo;s syndrome, and systemic sclerosis. Therefore, improving vitamin D deficiency in JIA patients with appropriate vitamin D supplementation may be helpful [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, some studies have not found a correlation between insufficient vitamin D levels and active JIA or more severe disease characteristics [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough numerous JIA studies have reported poor levels of vitamin D in JIA patients, the relationship between vitamin D and JIA remains controversial. Thorsen et al.\u0026rsquo;s work and a Mendel randomized study also revealed that there was no causal relationship between vitamin D level and JIA. Specific polymorphisms in the vitamin D family genes were associated with uveitis in patients with JIA, AS, and Behcet\u0026rsquo;s disease [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Unlike RA, there is no specific relationship between vitamin D receptor polymorphism and the development of SLE, and there may not be a causal relationship with AS [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The above indicates that the mechanism of vitamin D regulating immune response has high heterogeneity in distinct diseases.\u003c/p\u003e \u003cp\u003eThrough interactive-stratified analysis, we found that gender had a considerable impact on the vitamin D status of JIA patients. Specifically, the vitamin D levels of female patients with oJIA and undifferentiated JIA were significantly higher than those with sJIA, but one study from Norway did not indicate any differences in vitamin D levels between genders [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. There are also differences in the correlation between gender and vitamin D deficiency in the population. The study by Song et al. demonstrated that in China, the average vitamin D level of women tends to be lower than that of men [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Studies from other countries have reported a significantly higher proportion of vitamin D deficiency in girls compared to boys [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e], and lower levels of vitamin D in female patients with Sjogren\u0026rsquo;s syndrome compared to the control group [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Some opposite findings have shown that the prevalence of vitamin D deficiency is higher in male participants than in females [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. In addition, a study in T\u0026uuml;rkiye observed that at the end of summer, women had a higher proportion of vitamin D deficiency, while at the end of winter, there was no significant correlation between gender and vitamin D levels [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. These may be due to limited outdoor activities for women, clothing, and the use of sunscreen products, resulting in less sunlight exposure for women [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The outcomes might stem from the intricate interplay of factors influencing vitamin D levels.\u003c/p\u003e \u003cp\u003eMoreover, our findings suggest that being overweight might be a risk factor for vitamin D deficiency in children with JIA. There was a significant correlation between obesity and increased involvement of lower limb joints in JIA patients at baseline, and obesity might have negative effects on the course and treatment of JIA [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], and the differences in dosage may lead to inadequate conventional administration in obese children [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The results of the meta-analysis indicated the inverse relationship between obesity indicators and vitamin D levels, but supplementing with vitamin D did not seem to reduce any obesity indicators, and more research is needed to elucidate the underlying pathophysiological mechanisms [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eInterestingly, there were inconsistent results in our study regarding the relationship between decreased bone mineral density and vitamin D levels. Univariable analysis suggests a negative correlation between vitamin D levels and decreased BMD. Low bone mass is one of the complications of JIA, and serum vitamin D levels are significantly positively correlated with the Z-score of BMD. In JIA, osteoporosis is more pronounced in the femoral neck and bone compared to the lumbar spine [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Supplementation of vitamin D improved serum vitamin D levels in children with persistent active pJIA, but bone mineral density remained unchanged. On the other hand, supplementation of vitamin D significantly increased bone mineral density in JIA patients receiving systemic corticosteroid treatment, but the average bone mineral density rapidly decreased after discontinuing vitamin D supplementation [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. On the contrary, our multivariable analyses showed biases in the positive and negative relationships between vitamin D levels and decreased BMD across different groups. The meta-analysis of the vitamin D test demonstrated that when baseline vitamin D\u0026thinsp;\u0026gt;\u0026thinsp;40 nmol/L, there was no effect on bone mineral density or fracture risk [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The meta-analysis of vitamin D supplementation (not taken simultaneously with calcium) also found no effect in preventing fractures [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. It is worth noting that studies have exposed that the combination of vitamin K and D can significantly improve total bone mineral density [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The interaction of genetic, hormonal, nutritional, immune, or pharmacological stimuli influences bone metabolism and homeostasis. Skeletal cell function, Ca and vitamin D homeostasis, sex hormone metabolism, and puberty simultaneously affect bone health. Thus, these contradictory findings are not convincing enough to support the benefits of high-dose vitamin D supplementation for bone health, and more comprehensive assessments are urgent for children with high risk of vitamin D deficiency in prevention, treatment, and follow-up processes [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSo far, vitamin D deficiency and bone damage are still important issues during the growth and development of JIA. Nonetheless, the effectiveness of vitamin D supplements in preventing and treating diseases remains to be confirmed [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Marini F et al. found that the suboptimal status of vitamin D in JIA patients couldn\u0026rsquo;t be improved by vitamin D supplementation [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. There are also studies indicating that MTX treatment can further reduce the concentration of vitamin D [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Considering the high incidence of vitamin D deficiency in JIA patients and the use of steroids, guidelines recommend providing 2\u0026ndash;3 times the dose of vitamin D to children with rheumatic diseases receiving systemic steroid treatment [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. However, a prospective randomized trial involving 42 JIA patients illustrated that supplementing with cholecalciferol (2000 IU/day) for 24 weeks could increase serum vitamin D levels in JIA patients without reducing disease activity or improving BMD [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Patients with severe JIA may need more supplements to maintain normal vitamin D levels. Studies with long-term observation and a larger sample are required to investigate the relationship between vitamin D levels and disease activity among JIA and its subtypes [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOur study fully considers the relationship between early JIA disease and vitamin D, the characteristics of JIA, and the relationship between inflammatory markers and vitamin D levels. However, serum vitamin D levels are subject to multiple confounding factors. Since vitamin D is primarily synthesized in the skin upon exposure to ultraviolet B (UVB) radiation [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], its levels vary considerably by geography and season, particularly in high-latitude regions where winter UVB exposure is insufficient [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The use of sunscreen and increased indoor activities in modern lifestyles further limit skin synthesis [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. Insufficient consumption of foods rich in vitamin D, such as fish and dairy products, can lead to a decrease in vitamin D levels [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Given the research on the benefits of vitamin D supplementation during the previous COVID-19 pandemic, doctors now more frequently recommend consuming vitamin D-rich foods or supplements during seasons with insufficient sunlight exposure [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. This may explain the univariable analysis finding that JIA patients tested in winter had higher serum vitamin D levels than those tested in other seasons, possibly due to non-iatrogenic interventions. Additionally, there are significant differences in dietary culture among different regions, which may partially explain the heterogeneity of vitamin D levels observed in various studies [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. After strictly controlling for confounding factors, we found that the impact of JIA diagnostic features on vitamin D levels was insignificant. However, there was a significant negative correlation between inflammatory indicators and vitamin D levels, strongly suggesting the impact of inflammation on vitamin D. Moreover, individuals diagnosed with sJIA and RF-positive pJIA exhibited lower vitamin D levels compared to those with oJIA and undifferentiated JIA. This discrepancy could serve as a useful reference for rheumatologists in determining the necessity and timing of vitamin D supplementation for JIA patients.\u003c/p\u003e \u003cp\u003eThere were some limitations in this study. As a retrospective investigation, it primarily focused on baseline data from patients without dynamic follow-up, treatment, or vitamin D supplementation, and did not account for potential confounding factors that may influence vitamin D levels, such as sunlight exposure and dietary intake. Secondly, although the diagnostic season showed correlation with vitamin D levels, this association might be influenced by unmeasured factors, including geographical variations, UVB exposure, and metabolic differences. Future prospective studies are needed to establish optimal vitamin D therapeutic strategies and maintenance levels to enhance clinical management of vitamin D supplementation in JIA patients.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOur findings demonstrated that there were notable variations in vitamin D levels between the various JIA subtypes. In the early period of disease, active sJIA patients had significantly lower vitamin D levels than oJIA, RF-negative pJIA, ERA, and undifferentiated JIA patients. Conversely, patients with RF-positive pJIA had higher vitamin D levels than those in sJIA patients without significant differences. The substantial negative connection between vitamin D levels and inflammatory indicators implies the connection between vitamin D insufficiency and inflammation in JIA. We built a multivariable generalized linear regression model and found markedly lower vitamin D levels in untreated and new-onset sJIA patients, which provides pediatric physicians with clinical support for individualized treatment strategies for vitamin D in JIA [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eJuvenile idiopathic arthritis (JIA), Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), International League Against Rheumatology (ILAR), Pediatric Rheumatology International Trials Organization (PRINTO), Rheumatoid arthritis (RA), Systemic lupus erythematosus (SLE), Ankylosing spondylitis (AS), Calcium (Ca), Phosphorus (P), Bone mineral density (BMD), Body mass index (BMI), Interleukin (IL), Rheumatoid factor (RF), Anti-cyclic citrullinated antibodies (anti-CCP), Anti-nuclear antibodies (ANA), Alkaline phosphatase (ALP), Standard deviation (SD), Inter-quartile range (IQR), Confidence intervals (CI), Kilograms (kg), Oligoarticular JIA (oJIA), Systemic JIA (sJIA), Polyarticular JIA (pJIA), Enthesitis-related arthritis (ERA), T helper (Th) cell.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participant\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study adhered to according to the ethical guidelines of the Helsinki Declaration and was approved by the Human Research Ethics Committee of the Children’s Hospital of Chongqing Medical University [the reference number of the ethical approval: 2022 (52)]. All data were captured through a retrospective review of the electronic medical records from the patient’s regular visits. Our study has already obtained the necessary informed consent from the participants’ parents or legal guardians of pediatric patients, including those younger than 16.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analysed during this study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis work was supported by grants from the National Key R\u0026amp;D Program of China (No. 2021YFC2702003).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eXM.T and XW.L designed the study. YZ.H and XW.L collected the data, and drafted the manuscript. YX.C assisted in data filtering. XW.L, MW.D, and YZ.H conducted the statistical analysis. XM.T reviewed and revised the manuscript. All authors have reviewed the manuscript and approved the final submission.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are grateful to the patients and thank all the investigators who participated in the study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eRavelli A, Martini A. Juvenile idiopathic arthritis. The Lancet 2007;369:767\u0026ndash;78. https://doi.org/10.1016/S0140-6736(07)60363-8.\u003c/li\u003e\n \u003cli\u003ePetty RE, Southwood TR, Manners P, Baum J, Glass DN, Goldenberg J, et al. International League of Associations for Rheumatology classification of juvenile idiopathic arthritis: second revision, Edmonton, 2001. 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What do we know about juvenile idiopathic arthritis and vitamin D? A systematic literature review and meta-analysis of current evidence. Clin Rheumatol 2013;32:729\u0026ndash;34. https://doi.org/10.1007/s10067-012-2159-1.\u003c/li\u003e\n \u003cli\u003eChambers ES, Nanzer AM, Pfeffer PE, Richards DF, Timms PM, Martineau AR, et al. Distinct endotypes of steroid-resistant asthma characterized by IL-17Ahigh and IFN-\u0026gamma;high immunophenotypes: Potential benefits of calcitriol. J Allergy Clin Immunol 2015;136:628-637. e4. https://doi.org/10.1016/j.jaci.2015.01.026.\u003c/li\u003e\n \u003cli\u003eKim H, Baek S, Hong S-M, Lee J, Jung SM, Lee J, et al. 1, 25-dihydroxy vitamin D3 and interleukin-6 blockade synergistically regulate rheumatoid arthritis by suppressing interleukin-17 production and osteoclastogenesis. J Korean Med Sci 2020;35. https://doi.org/10.3346/jkms.2020.35.e40.\u003c/li\u003e\n \u003cli\u003eSong GG, Bae S-C, Lee YH. Association between vitamin D intake and the risk of rheumatoid arthritis: a meta-analysis. Clin Rheumatol 2012;31:1733\u0026ndash;9. https://doi.org/10.1007/s10067-012-2080-7.\u003c/li\u003e\n \u003cli\u003eBouaddi I, Rostom S, El Badri D, Hassani A, Chkirate B, Abouqal R, et al. Vitamin D concentrations and disease activity in Moroccan children with juvenile idiopathic arthritis. BMC Musculoskelet Disord 2014;15:1\u0026ndash;5. https://doi.org/10.1186/1471-2474-15-115.\u003c/li\u003e\n \u003cli\u003e\u0026Ccedil;omak E, Doğan \u0026Ccedil;S, Uslu-G\u0026ouml;k\u0026ccedil;eoğlu A, Akbaş H, \u0026Ouml;zdem S, Koyun M, et al. Association between vitamin D deficiency and disease activity in juvenile idiopathic arthritis. Turk J Pediatr 2014;56:626\u0026ndash;31.\u003c/li\u003e\n \u003cli\u003eNandi M, Mullick MAS, Nandy A, Samanta M, Sarkar S, Sabui TK. Evaluation of vitamin D profile in juvenile idiopathic arthritis. Mod Rheumatol 2022;32:792\u0026ndash;6. https://doi.org/10.1093/mr/roab053.\u003c/li\u003e\n \u003cli\u003eWu C-Y, Yang H-Y, Luo S-F, Huang J-L, Lai J-H. Vitamin d supplementation in patients with juvenile idiopathic arthritis. Nutrients 2022;14:1538. https://doi.org/10.3390/nu14081538.\u003c/li\u003e\n \u003cli\u003eStawicki MK, Abramowicz P, G\u0026oacute;ralczyk A, Młyńczyk J, Kondratiuk A, Konstantynowicz J. Prevalence of vitamin D deficiency in patients treated for juvenile idiopathic arthritis and potential role of methotrexate: a preliminary study. Nutrients 2022;14:1645. https://doi.org/10.3390/nu14081645.\u003c/li\u003e\n \u003cli\u003eCetrelli L, Bletsa A, Lundestad A, Gil EG, Fischer J, Halbig J, et al. Vitamin D, oral health, and disease characteristics in juvenile idiopathic arthritis: a multicenter cross-sectional study. BMC Oral Health 2022;22:333. https://doi.org/10.1186/s12903-022-02349-1.\u003c/li\u003e\n \u003cli\u003ePillar S, Amer R. The association between vitamin D and uveitis: A comprehensive review. Surv Ophthalmol 2022;67:321\u0026ndash;30. https://doi.org/10.1016/j.survophthal.2021.07.006.\u003c/li\u003e\n \u003cli\u003eIsa H, Almaliki M, Alsabea A, Mohamed A. Vitamin D deficiency in healthy children in Bahrain: do gender and age matter? East Mediterr Health J 2020;26:260\u0026ndash;7. https://doi.org/10.26719/emhj.19.084.\u003c/li\u003e\n \u003cli\u003eAlQuaiz AM, Kazi A, Fouda M, Alyousefi N. Age and gender differences in the prevalence and correlates of vitamin D deficiency. Arch Osteoporos 2018;13:1\u0026ndash;11. https://doi.org/10.1007/s11657-018-0461-5.\u003c/li\u003e\n \u003cli\u003eErol M, Yiğit \u0026Ouml;, K\u0026uuml;\u0026ccedil;\u0026uuml;k SH, Bostan Gayret \u0026Ouml;. Vitamin D Deficiency in Children and Adolescents in Bağcılar, İstanbul. J Clin Res Pediatr Endocrinol 2015;7:134\u0026ndash;9. https://doi.org/10.4274/jcrpe.1888.\u003c/li\u003e\n \u003cli\u003eAl Shaikh AM, Abaalkhail B, Soliman A, Kaddam I, Aseri K, Al Saleh Y, et al. Prevalence of Vitamin D Deficiency and Calcium Homeostasis in Saudi Children. J Clin Res Pediatr Endocrinol 2016;8:461\u0026ndash;7. https://doi.org/10.4274/jcrpe.3301.\u003c/li\u003e\n \u003cli\u003eGiani T, De Masi S, Maccora I, Tirelli F, Simonini G, Falconi M, et al. The influence of overweight and obesity on treatment response in juvenile idiopathic arthritis. Front Pharmacol 2019;10:637. https://doi.org/10.3389/fphar.2019.00637.\u003c/li\u003e\n \u003cli\u003eBalevic SJ, Becker ML, Gonzalez D, Funk RS. Low etanercept concentrations in children with obesity and juvenile idiopathic arthritis. J Pediatr Pharmacol Ther 2021;26:809\u0026ndash;14. https://doi.org/10.5863/1551-6776-26.8.809.\u003c/li\u003e\n \u003cli\u003eKarampela I, Sakelliou A, Vallianou N, Christodoulatos G-S, Magkos F, Dalamaga M. Vitamin D and obesity: current evidence and controversies. Curr Obes Rep 2021;10:162\u0026ndash;80. https://doi.org/10.1007/s13679-021-00433-1.\u003c/li\u003e\n \u003cli\u003eCharuvanij S, Malakorn H, Densupsoontorn N, Nakavachara P. Bone Mineral density and serum 25OHD in children and adolescents with juvenile idiopathic arthritis. Clin Pediatr (Phila) 2023;62:456\u0026ndash;65. https://doi.org/10.1177/00099228221136982.\u003c/li\u003e\n \u003cli\u003eReid IR, Bolland MJ, Grey A. Effects of vitamin D supplements on bone mineral density: a systematic review and meta-analysis. The Lancet 2014;383:146\u0026ndash;55.\u003c/li\u003e\n \u003cli\u003eKuang X, Liu C, Guo X, Li K, Deng Q, Li D. The combination effect of vitamin K and vitamin D on human bone quality: A meta-analysis of randomized controlled trials. Food Funct 2020;11:3280\u0026ndash;97. https://doi.org/10.1039/C9FO03063H.\u003c/li\u003e\n \u003cli\u003eMarini F, Falcini F, Stagi S, Fabbri S, Ciuffi S, Rigante D, et al. Study of vitamin D status and vitamin D receptor polymorphisms in a cohort of Italian patients with juvenile idiopathic arthritis. Sci Rep 2020;10:17550. https://doi.org/10.1038/s41598-020-74861-9.\u003c/li\u003e\n \u003cli\u003eGr\u0026ouml;ber U, Spitz J, Reichrath J, Kisters K, Holick MF. Vitamin D: update 2013: from rickets prophylaxis to general preventive healthcare. Dermatoendocrinol 2013;5:331\u0026ndash;47. https://doi.org/10.4161/derm.26738.\u003c/li\u003e\n \u003cli\u003eTang T, Zhang Y, Luo C, Liu M, Xu L, Tang X. Adjunctive vitamin D for the treatment of active juvenile idiopathic arthritis: An open‑label, prospective, randomized controlled trial. Exp Ther Med 2019;18:4921\u0026ndash;6.\u003c/li\u003e\n \u003cli\u003eStawicki MK, Abramowicz P, Sokolowska G, Wołejszo S, Grant WB, Konstantynowicz J. Can vitamin D be an adjuvant therapy for juvenile rheumatic diseases? Rheumatol Int 2023;43:1993\u0026ndash;2009. https://doi.org/10.1007/s00296-023-05411-5.\u003c/li\u003e\n \u003cli\u003eFerder L, Mart\u0026iacute;n Gim\u0026eacute;nez VM, Inserra F, et al. Vitamin D supplementation as a rational pharmacological approach in the COVID-19 pandemic. Am J Physiol Lung Cell Mol Physiol. 2020;319(6):L941-L948. doi:10.1152/ajplung.00186.2020\u003c/li\u003e\n \u003cli\u003eKopeček M, H\u0026ouml;schl C. Season of the year, vitamin D and COVID-19. Ročn\u0026iacute; obdob\u0026iacute;, vitamin D a COVID-19. Cas Lek Cesk. 2020;159(7-8):312-316.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 3 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Juvenile idiopathic arthritis, Vitamin D, Disease onset, Inflammation","lastPublishedDoi":"10.21203/rs.3.rs-5659951/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5659951/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eVitamin D deficiency is prevalent in children with juvenile idiopathic arthritis (JIA). Prevention and supplementation with vitamin D may help improve diseases. Understanding subtype-specific variations in vitamin D levels before initiating treatment could provide valuable insights for early monitoring.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThis study included 236 newly diagnosed, untreated children with active JIA who were admitted to Chongqing Medical University Children's Hospital between May 2019 and April 2024. Demographic and clinical characteristics, inflammatory markers, vitamin D levels, bone metabolism, and bone mineral density were retrospectively reviewed. Univariable and multivariable analyses were performed to identify factors affecting vitamin D levels and assess intergroup differences among JIA subtypes.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eUnivariable analysis showed positive correlations of calcium and phosphorus levels with vitamin D levels, while body weight, body mass index, normalized erythrocyte sedimentation rate (ESR), and IL-6 exhibited negative correlations (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Multivariable analysis identified reduced bone mineral density, normalized ESR, and normalized C-reactive protein (CRP) as significant variables associated with vitamin D levels. The stratified analysis revealed notable differences in gender, weight, and bone density across JIA subtypes.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eVitamin D deficiency is associated with inflammation in JIA. Findings from the multivariate generalized linear regression model emphasize the distinct patterns of vitamin D levels and their influencing factors across JIA subtypes, offering critical insights for early monitoring and informed clinical decision-making before treatment.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTrial registration\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe study was registered on chictr.org.cn on June 12, 2022 (ID: ChiCTR2200060798).\u003c/p\u003e","manuscriptTitle":"Subtype-specific profiles and predictive factors for early evaluation of vitamin D levels in newly diagnosed active juvenile idiopathic arthritis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-06 12:35:26","doi":"10.21203/rs.3.rs-5659951/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f9a4e4c8-34ed-4298-aba9-5912e809c138","owner":[],"postedDate":"May 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-01T07:38:59+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-06 12:35:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5659951","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5659951","identity":"rs-5659951","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}