Therapies and Treatment Responses for Hemophagocytic Lymphohistiocytosis in Children: A Single-center Retrospective Study

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This retrospective study aims to evaluate the effectiveness of different therapies and identify early treatment responses maybe for indicators to overall survival. The study involved 102 patients from January 1, 2012, to December 31, 2022, using Cox regression to identify prognostic risk factors. Causal mediation analysis assessed the impact of various treatments on overall survival through the mediator of complete remission at 4 or 8 weeks. Achieving complete remission at 4 or 8 weeks suggests a favorable prognosis. However central nervous system involvement, high lactate dehydrogenase levels, and blood purification alone indicate poor prognosis (P < 0.05). HLH-94/04 protocol treatments had higher survival rates at 81.3% and 76.6%, compared to blood purification alone or combined with HLH-94/04 protocol treatments at 23.4% and 15.4%. Complete remission at 4 or 8 weeks resulted in higher survival rates of 90.7% and 92.3% respectively, compared to 2.9% and 3.4% for partial or no response. Compared to HLH-94 protocol treatment, blood purification alone has a 33.28% effect mediated by inducing complete remission at 4 weeks, which decreases to 26.56% at 8 weeks. Blood purification combined with HLH-94/04 protocol treatment with a higher mediation effect was 79.88% at 4 weeks compared to 51.95% at 8 weeks. HLH-94/04 protocol treatments led to complete remission and improved survival rates than Blood purification alone or combined with HLH-94/04 protocol treatment. Complete remission at 4 weeks may be a better mediator of overall survival than that at 8 weeks. Hemophagocytic Lymphohistiocytosis Pediatric Mediation Analysis Blood Purification Treatment Responses Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease caused by an overactive immune response to antigens, resulting in uncontrolled activation of immune cells and cytokine storms[ 1 ]. HLH-94 and HLH-04 guidelines have significantly improved the diagnosis of HLH and increased the survival rate. This multi-drug cocktail therapy is a practical pan-target therapeutic approach that acts on T cells/ macrophages by mainly inhibiting hyperinflammatory syndrome and/or hypertyrosinemia. However, due to the diseases’ complexity and heterogeneity, many patients still do not respond well to it and experience a range of complications, which can ultimately lead to fatalities[ 2 ]. Extracorporeal blood purification techniques, which involve a combination of plasma exchange and continuous renal replacement therapy, have been effectively utilized to eliminate inflammatory mediators and toxins of varying sizes while also providing support to the functions of multiple organs in cases of Epstein-Barr virus-HLH (EBV-HLH) [ 3 ]. However, there have not been enough studies to confirm this method of treating HLH. Therefore, it is important to identify effective therapeutic regimens for managing HLH and properly develop effective strategies for managing the condition through treatment response evaluation. Causal mediation analysis: this methodology may be applied to analyze direct and indirect natural effects for almost any combination of variable types[ 4 ]. The total effect of the treatment comprises two parts: the indirect effect and the direct effect. Mediation analysis allows us to shift our focus from determining the effectiveness to understanding the mechanism of action[ 5 ]. To explain how the intervention (in this case, e.g., HLH-94/04 protocol treatments) affects the outcome (overall survival) mainly mediated by mediators (complete remission at 4 or 8 weeks). These mediators could potentially serve as surrogate endpoints to provide better guidance for subsequent treatment. Therefore, we conducted a study on 102 pediatric patients diagnosed with HLH at a single center. This study aimed to consider the clinical features of patients who underwent various therapies and assess the risk factors associated with their prognosis. Additionally, we used causal mediation analysis to examine whether the appropriate mediators mediated the effect of different treatments on Over Survival (OS), such as achieving complete disease remission at 4 or 8 weeks. Patient and Method A retrospective cohort study was conducted on individuals diagnosed with HLH at Zhujiang Hospital, Southern Medical University, from January 1, 2012, to December 31, 2022. The last follow-up time was May 1, 2023. The inclusion criteria of patients with HLH were the following: (1) patients aged ≤ 18 years and (2) patients diagnosed with revised HLH-04 diagnostic criteria[ 6 ]. Patients whose outcome was not tracked during the survey and whose arrogance HLH was triggered by medical interventions or treatments that activate the immune system were excluded. Each patient collected demographic, clinical, and laboratory data including the following data: age, gender, family history, fever duration, presence of hepatomegaly, splenomegaly, lymphadenopathy, Laboratory data, treatment prescribed, and outcome. The laboratory diagnostic criteria for soluble CD25 levels (n = 28) and natural killer cells (n = 16) were only accessible to some patients with additional medical insurance. As a result, these data were not analyzed in this study. The HLH-94 and HLH-04 protocols were used to treat HLH [ 7 , 8 ]. Blood purification involves plasma exchange and/or continuous renal replacement therapy following diagnosis. Of the 35 patients, 6 underwent plasma exchange therapy alone, while the remaining 29 received both plasma exchange and continuous renal replacement therapy. Other treatments include corticosteroids, intravenous immunoglobulin, and/or ruxolitinib therapy. The study complied with the Declaration of Helsinki (revised in 2013) and was approved by the Institutional Review Board of Zhujiang Hospital, Southern Medical University (ID:2023-KY-258-01). We assessed therapeutic responses at 4 or 8 weeks and monitored dynamic responses based on response time and disease progression. Overall mortality was evaluated as death occurring during the follow-up period. The Early treatment response was defined as the resolution of all clinical manifestations and normalization of HLH-related laboratory findings either complete blood count or other HLH-related laboratory parameters at 4 or 8 weeks. Patients who meet the following criteria at 4 or 8 weeks will be classified as having achieved a complete response (CR): absence of fever, absence of splenomegaly, absence of cytopenia, absence of hypertriglyceridemia, ferritin levels below 500 𝜇g/L, and normal cerebral spinal fluid. A partial response (PR) is generally defined as an improvement of at least ≥ 2 symptoms and laboratory markers within two weeks after initiation of treatment. No response (NR) was considered a treatment failure and/or 50% worsening in two or more signs or laboratory abnormalities within 4 or 8 weeks[ 9 ]. Statistical analysis Descriptive statistics (medians, ranges and standard deviations or standard errors) were used to summarize data. The Mann-Whitney U test or chi-square test was used to compare the differences between the two groups according to the category of variables. Univariate and multivariate Cox proportional hazards models evaluate the correlations among clinical data, laboratory variables, and outcomes. Statistical significance was defined as a two-tailed P value < 0.05. The OS was measured as the time from HLH diagnosis to the date of death from any cause or the last follow-up. Causal mediation analysis, a sophisticated epidemiological approach used to determine causal inference, explains the process through which the intervention (in this study, various treatments) affects the outcome (in this study, overall survival) through mediators (in this study, therapeutic responses) [ 10 ]. Therapeutic responses at 4 or 8 weeks as mediators were evaluated in this study. Baseline covariates in mediation analysis included Epstein-Barr virus (EBV) infection, central nervous system-HLH (CNS-HLH), splenomegaly, pediatric intensive care unit (PICU) admission, ferritin, lactate dehydrogenase (LDH), albumin (ALB), aspartate transferase (AST), total bilirubin (TBIL), and direct bilirubin (DBIL). The direct, indirect, and total effects of varied treatments on survival outcomes were estimated using mediation analysis[ 11 , 12 ]. All statistical analyses were performed using SPSS version 26.0 (IBM, Armonk, NY) and R version 4.0.2. Result 4.1 Patients’ characteristics in clinical and Laboratory In this study, 102 patients were enrolled. Of these, 31 patients (30.4%) underwent the HLH-94 protocol treatment, while 22 (21.6%) received the HLH-04 protocol. Additionally, 35 patients underwent blood purification in the PICU, with 13 receiving blood purification alone and the remaining 22 receiving blood purification in combination with HLH-94/04 protocol treatment (Fig. 1 ). The male-to-female ratio in the study was 1.55 (62:40) as shown in Table 1 . The median age of patients with HLH was 3 years, with 49.02% being younger than 2 years and only 5.88% being older than 10 years. Five patients were diagnosed with primary HLH and were found to have specific gene mutations by Sanger sequencing, including X-linked lymphoproliferative Disease Type 1 (XLP1), X-linked lymphoproliferative syndrome-2 (XLP2), Magnesium transporter 1 (MAGT1), Unc-13 Homolog D (UNC13D), and SH2 Domain Containing 1A (SH2D1A). Fever was the most common symptom experienced by patients (98.0%), along with high ferritin levels. Additionally, some patients also exhibited splenomegaly (67.8%) and CNS involvement (12.8%). The level of sIL-2R/sCD25 ranged from 1686 to 108360 µ/ml. Natural killer cell activity was reduced or absent in six patients. Table 1 Demographic and clinical characteristics among patients with HLH All (n = 102) HLH-94 protocol treatment (n = 31) HLH-04 protocol treatment (n = 22) Blood purification alone(n = 13) Blood purification and HLH-94/04 protocol (n = 22) Other treatments a (n = 14) P value Gender, male, n (%) 62 (60.8) 20 (64.5) 10 (45.5) 9 (69.2) 13 (59.1) 10 (71.4) 0.488 Age, y, median (range) 3 (0.2,18) 3 (0.4,15) 2(0.8,13) 3 (0.3,8) 3 (0.2,9) 2 (0.2,18) 0.465 Primary HLH , n (%) 5 (4.9) 3(9.7) - - 2(9.1) - 0.394 Secondary HLH EBV infection, and (%) 68 (66.7) 23 (74.2) 15 (68.2) 6 (46.2) 16 (72.2) 8 (57.1) 0.378 Other infections, and (%) 6 (5.9) 1 (3.2) - 2 (15.4) 2 (9.1) 1 (7.1) 0.362 Malignancies, n (%) 2 (2.0) 1 (3.2) - - 1 (4.5) - 0.735 Autoimmune diseases, n (%) 4 (3.9) 1 (3.2) 1 (4.5) 1 (7.7) - 1 (7.1) 0.766 Unknown, n (%) 17 (16.7) 2 (6.5) 6 (27.3) 4 (30.8) 1 (4.5) 4 (28.6) 0.045 * HLH-04 criteria Fever, n (%) 100 (98.0) 31 (100) 20 (90.9) 13 (100) 22 (100) 14 (100) 0.115 Splenomegaly, n (%) 69 (67.8) 23 (74.2) 16 (72.7) 9 (69.2) 13 (59.1) 8 (57.1) 0.677 Bicytopenia, n (%) 76 (74.5) 23 (74.2) 17 (77.3) 9 (69.2) 16 (72.7) 11 (78.6) 0.979 Hypertriglyceridemia and/or hypofibrinogenemia, n (%) 82 (80.4) 24 (80.0) 18 (81.8) 12 (92.3) 17 (81.1) 11 (78.6) 0.887 Ferritin, µg/L, median (range) 16826 (568, 177730) 8178 (568,73435) 12748 (906,90309) 11335 (1324,83027) 25970 (1846,177730) 37191.5 (1734,80287) 0.007 * Hemophagocytosis, n (%) 93 (91.8) 31 (100) 19 (86.4) 13 (100) 19 (100) 11 (78.6) 0.082 H Score, median (range) 270 (141,319) 257 (171,319) 268 (141,319) 269 (174,319) 289 (239,319) 266 (244,304) 0.109 CNS involvement, n (%) 13 (12.8) 2 (6.5) 1 (4.5) 2 (15.4) 8 (36.4) - 0.004 * Length of onset to diagnosis, d, median (range) 11(1,48) 11(5,41) 14 (3,48) 11(4,42) 8.5(2,35) 12 (1,32) 0.128 PICU, n (%) 78 (76.5) 21 (67.7) 14 (63.6) 13 (100) 21 (95.5) 9 (64.3) 0.012 * Length of PICU, d, median (range) 8 (0,49) 3 (0,37) 4.5 (0,26) 9 (0,18) 14 (0,49) 3.5 (0,33) 0.002* Assessment of Response, n (%) CR at 4 weeks 59 (57.8) 24 (77.4) 19 (86.4) 2 (15.4) 8 (36.4) 6 (42.9) < 0.001 * CR at 8 weeks 54 (52.9) 22 (71.0) 17 (77.3) 2 (15.4) 7 (31.8) 6 (42.9) < 0.001 * a Other treatments include corticosteroids, intravenous immunoglobulin therapy, and/or ruxolitinib therapy. Abbreviations: HLH: hemophagocytic lymphohistiocytosis; EBV, Epstein-Barr virus; PICU, Pediatric Intensive Care Unit; CNS, Central nervous system; CR: complete response. * p < 0.05. The CR rates of HLH patients at 4 weeks and 8 weeks were 57.8% and 52.9% respectively. HLH-04 regimen had a better CR rate of 86.4% at 4 weeks compared to the HLH-94 regimen at 77.4%. Blood purification alone or with the HLH-94/04 regimen had lower CR rates at 4 weeks at 15.4% and 36.4% respectively. However, patients in these two groups had higher levels of central infiltration, ferritin, and bilirubin than the HLH-94/04 treatment group. Additionally, they had higher rates of PICU treatment and longer PICU stays (P < 0.05) (Supplementary Table S1 ). The 10-year overall survival rate for HLH was 54.3%. Among the various treatment protocols, the HLH-94/04 protocol demonstrated the highest survival rates at 81.3% and 76.6%, respectively. However, when blood purification was administered alone or in combination with the HLH-94/04 protocol, the survival rates were significantly lower, at 15.4% and 23.4%, respectively (Fig. 2 a). Patients who achieved CR at 4 or 8 weeks had a higher survival rate of 90.7% and 92.3%, respectively. On the other hand, patients who partially responded or did not respond at 4 or 8 weeks had a significantly lower survival rate of 2.9% and 3.4%, respectively (Fig. 2 b). 4.2 Prognostic factors by Cox regression According to the results of the univariate Cox regression analysis, various risk factors contributing to overall mortality were found, such as EBV infection, splenomegaly, CNS involvement, admission to the PICU, elevated levels of ferritin, AST, LDH, TBIL, DBIL, different treatments, and CR at 4 or 8 weeks (refer to Supplementary Table S2). After performing COX regression analysis and adjusting for multiple variables, it was determined that patients with central nervous system involvement and elevated LDH levels faced a higher risk of mortality in HLH. These factors were found to be independently significant prognostic risk factors for the parameters of CR at 4 or 8 weeks (Fig. 3 ) (P < 0.05). In comparison to the HLH-94 protocol treatment, it was observed that blood purification alone or other treatments were associated with an increased risk of death. Conversely, the HLH-04 protocol treatment showed an increased risk of death, although it did not reach statistical significance. Furthermore, the combination of blood purification with the HLH-94/04 protocol treatment decreased the risk of death, but this finding was not statistically significant. 3.4 Causal mediation analysis Since the patients who received various treatments displayed different early treatment responses and OS, we investigated whether CR at 4 or 8 weeks was the primary mediator of the treatment effect on OS (Fig. 4 ). Our mediation analysis revealed that, compared to the HLH-94 protocol treatment, the HLH-04 protocol treatment did not have a significant mediating effect on patient OS (P > 0.05). Blood purification has been shown to have indirect and direct effects on decreasing patient overall survival (OS), with a mediating effect of 33.28% at 4 weeks and 26.56% at 8 weeks. Blood purification combined with the HLH-94/04 protocol treatment showed that CR at 4 or 8 weeks mediated a major effect of 79.88% or 51.95% on patient OS, but the direct effect was insignificant (P > 0.05). Furthermore, the percentage of mediating effects decreased in CR at 8 weeks compared to CR at 4 weeks. CR at 4 weeks may be a better mediator in the OS treatments than CR at 8 weeks. Discussion HLH is a severe syndrome characterized by hyperinflammation and aberrant immune activation. The cytokine storm is a crucial factor in the pathogenesis of various hematological disorders. Underlying defects from primary genetic dysfunction or other etiologies that enable sustained activation of cytotoxic T cells are the core immunological features and pathogenesis of HLH[ 13 ]. Previous reports in adult patients showed that patients with disseminated intravascular coagulation, nosocomial infections and neurological symptoms had statistically significantly worse survival[ 14 ]. In pediatric patients with secondary HLH/MAS, thrombocytopenia was a predictor of mortality. This study of the pediatric population found that CNS involvement and elevated LDH levels were independent prognostic factors. Children and adults with HLH have different prognostic factors and require distinct treatment strategies[ 15 ]. The effectiveness and safety of blood purification have been reported in a small sample of patients with HLH [ 3 , 16 , 17 ]. In our study, the blood purification alone group fails to induce disease remission and increases the associated risk of death. This lack of improvement may be attributed to the potential side effects of blood purification treatment, such as coagulation disorders and fluctuations in drug concentration. These side effects counteracted the therapy's intended effects of supporting organ function and reducing inflammatory factors[ 18 ]. Nevertheless, it is worth mentioning that blood purification therapy may hold therapeutic advantages for patients with HLH combined with liver failure[ 19 ]. Blood purification treatment may be considered a supportive measure in cases where patients do not respond to HLH-1994 or HLH-2004 treatment or experience organ failure[ 20 ]. However, further research is necessary to fully understand its potential benefits and limitations. Blood purification combined with the HLH-94/04 protocol treatment may be more effective in improving long-term survival rates than using blood purification alone. However, due to the small sample size, it did not show significant improvement compared to the HLH-94 protocol treatment. Furthermore, according to our causal analysis, blood purification combined with chemotherapy has shown a 79.88% effectiveness in inducing disease remission compared to HLH-94, suggesting that it may be beneficial in inducing disease remission. In our study, the CR rates at 4 and 8 weeks of the HLH-94/04 protocol treatments were higher than those of blood purification alone or combined with the HLH-94/04 protocol treatments, resulting in a better survival rate. In other studies of children and adults with non-malignancy-related secondary HLH, lack of response at 8 weeks was the strongest predictor of poor OS [ 21 , 22 ]. Our study revealed that achieving CR at 4 or 8 weeks independently influenced the prognosis of HLH. Interestingly, we observed that the mediation effect of achieving CR at 4 weeks was more pronounced compared to achieving CR at 8 weeks. This suggests that achieving CR at 4 weeks may be a more appropriate mediator in impacting OS. Currently, there are few available data on whether patients who switch to a salvage regimen after the 4-week assessment have better survival rates than those who continue treatment. Based on the latest TPOG NHL protocol, patients who didn't respond to initial treatment at 4 weeks or experienced a relapse would receive more intensive chemotherapy and stem cell transplantation[ 23 ]. Early response assessment may predict a poor prognosis, which emphasizes the need to start salvaging treatment and quickly prepare for hematopoietic stem cell transplantation. This proactive approach can greatly contribute to maintaining stability and the patient's life [ 24 , 25 ]. Furthermore, an early response to treatment may serve as a substitute endpoint for modifying subsequent treatment. The study was conducted retrospectively, and the smaller number of patients in each treatment group may have introduced some bias into the results. Further prospective randomized controlled studies with large sample sizes are necessary to assess the potential benefits of blood purification therapy as a management strategy for HLH. Additionally, it is essential to determine whether 4-week or 8-week CR assessments are suitable for guiding subsequent intensive therapy or transplantation with hematopoietic stem cell transplantation. Conclusion In summary, the HLH-94/04 protocol treatments are considered the standard treatment for HLH. However, blood purification alone may not be beneficial, and the potential benefits of using it in combination with the HLH-94/04 protocol for managing HLH are still being investigated and require further study. Achieving complete remission at 4 weeks, as compared to 8 weeks, maybe a more suitable factor in overall survival. This distinction is crucial in determining the most effective treatment strategies and significantly impacts survival rates and prognosis. Declarations Acknowledgments We express our gratitude to the Department of Pediatric Hematology, the Department of Pediatric Surgery, and the Department of Pediatric Intensive Care Unit for their participation in our study, provision of data, and outstanding collaboration. We also thank Professor Chengfeng Zhang and Professor Peihua Cao for their help with statistical analysis. Contributions LH Y and DA L conceptualized and designed the study, drafted the initial manuscript, and provided critical review and revisions. LW, LL H, XL, YJ Z, JZ, JG Z, XL, LC L, and GM Z contributed to the data collection, conducted the initial analyses, and also provided critical review and revisions. LC Y also provided critical review and revisions. LH Y coordinated and supervised the data collection and provided critical review and revisions for important intellectual content. All authors contributed to the article, approved the submitted version, and played a significant role in the study. Competing interests The authors confirm that the research was carried out without commercial or financial interests that could be seen as a potential conflict of interest. Ethics declarations Ethics approval and consent to participate The study was approved by the Institutional Review Board of Zhujiang Hospital, Southern Medical University (ID:2023-KY-258-01). Consent for publication Written informed consent from the participant’s legal guardian/next of kin was not required to participate in this study in accordance with the national legislation and the institutional requirements. Availability of data and materials The datasets utilized and/or analyzed during the current study can be obtained from the corresponding author upon reasonable request. Requests may be sent to [email protected] . Funding The authors confirm that they did not receive any funds, grants, or other support during the preparation of this manuscript. Author information Authors and Affiliations Department of Pediatric Hematology, Zhujiang Hospital, Southern Medical University, Guangzhou, China Lihua Yu, Danna Lin, Li Wu, Lulu Huang, Xiaorong Lai, Yajie Zhang, Juan Zi, Jingxin Zhang, Xu Liao, Lichan Liang, Guanmei Zhang, Liucheng Yang, Lihua Yang Department of Pediatric Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China Liucheng Yang Corresponding author Correspondence to Liucheng Yang and Lihua Yang References Canna SW, Marsh RA. Pediatric hemophagocytic lymphohistiocytosis. Blood. 2020;135(16):1332-43. doi: 10.1182/blood.2019000936. Vallurupalli M, Berliner N. Emapalumab for the treatment of relapsed/refractory hemophagocytic lymphohistiocytosis. Blood. 2019;134(21):1783-6. doi: 10.1182/blood.2019002289. Huang P, Huang C, Xu H, Lu J, Tian R, Wang Z, et al. Early Use of Blood Purification in Severe Epstein-Barr Virus-Associated Hemophagocytic Syndrome. 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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-3862083","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":267241015,"identity":"674abc0e-6655-408a-9e2c-6f6dfd81f533","order_by":0,"name":"Lihua Yu","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Lihua","middleName":"","lastName":"Yu","suffix":""},{"id":267241016,"identity":"c138427d-4e78-47e4-8b06-aeadbef61bdc","order_by":1,"name":"Danna Lin","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Danna","middleName":"","lastName":"Lin","suffix":""},{"id":267241017,"identity":"98dfe356-8738-4396-b6ea-f491a8030eee","order_by":2,"name":"Li Wu","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Li","middleName":"","lastName":"Wu","suffix":""},{"id":267241018,"identity":"225e73a3-21e9-45a3-8310-ac27805a41c5","order_by":3,"name":"Lulu Huang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Lulu","middleName":"","lastName":"Huang","suffix":""},{"id":267241020,"identity":"47d44e67-fecd-4f6b-9b6f-85280b103f0c","order_by":4,"name":"Xiaorong Lai","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Xiaorong","middleName":"","lastName":"Lai","suffix":""},{"id":267241021,"identity":"681cb8ad-5182-429e-b48a-ddc1894fb784","order_by":5,"name":"Yajie Zhang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yajie","middleName":"","lastName":"Zhang","suffix":""},{"id":267241023,"identity":"8ed94e4a-292b-4bd4-a641-d76d033e168c","order_by":6,"name":"Juan Zi","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Zi","suffix":""},{"id":267241024,"identity":"3fb2569d-0cdc-4ad7-b1a2-c7eca1fa1bec","order_by":7,"name":"Jingxin Zhang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jingxin","middleName":"","lastName":"Zhang","suffix":""},{"id":267241026,"identity":"8fc7defc-4b43-47a1-8344-9f3abf847376","order_by":8,"name":"Xu Liao","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Xu","middleName":"","lastName":"Liao","suffix":""},{"id":267241028,"identity":"2849d612-2ab8-4520-a7ed-837b4883b7f0","order_by":9,"name":"Lichan Liang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Lichan","middleName":"","lastName":"Liang","suffix":""},{"id":267241031,"identity":"1e1aa1f9-45db-4d60-a7eb-39e5e5562536","order_by":10,"name":"Guanmei Zhang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Guanmei","middleName":"","lastName":"Zhang","suffix":""},{"id":267241033,"identity":"581d3de9-1f33-4607-9846-7b5a90fe8dcc","order_by":11,"name":"Liucheng Yang","email":"","orcid":"","institution":"Southern Medical University","correspondingAuthor":false,"prefix":"","firstName":"Liucheng","middleName":"","lastName":"Yang","suffix":""},{"id":267241034,"identity":"641f8f10-b6d1-4b26-86c5-76fc4b03f06d","order_by":12,"name":"Lihua Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3klEQVRIiWNgGAWjYDCCA2DSgseAgYHxQUJFDdFaJEBamA0enDlGvBYGoBY2yYctzIR18N0+Y/i54JeEjLlE8rOKxAY2Bv727gS8WiTP5RhLz+yT4LGckWZ2I3GHDIPEmbMb8GoxOMNjIM3bA/TLjQSgljNsDAYSuQS1GP+GaEn/VpDYxkyUFjNpnh8gLTlmDERpkTzDVmbN2wDUcuZNsUTCmWM8BP3Cd4Z5822ePzb2BsfTN378UVEjx9/ei18LAwOHAQNjG4LLQ0A5CLA/YGD4Q4S6UTAKRsEoGLkAAHqqR68miqhSAAAAAElFTkSuQmCC","orcid":"","institution":"Southern Medical University","correspondingAuthor":true,"prefix":"","firstName":"Lihua","middleName":"","lastName":"Yang","suffix":""}],"badges":[],"createdAt":"2024-01-14 04:29:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3862083/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3862083/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49767132,"identity":"b6c46541-6051-47d5-a641-4362c4b912d1","added_by":"auto","created_at":"2024-01-17 17:11:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":34524,"visible":true,"origin":"","legend":"\u003cp\u003eThe flow chart displays the distribution of enrolled patients.\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/36ff90cbddbcb3a1d2e97751.png"},{"id":49767133,"identity":"3aa04977-cf92-454a-acea-b94fff322042","added_by":"auto","created_at":"2024-01-17 17:11:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":240701,"visible":true,"origin":"","legend":"\u003cp\u003eThe survival outcomes were determined based on the effectiveness of treatments (A) and the treatment responses (B) for hemophagocytic lymphohistiocytosis.\u003c/p\u003e","description":"","filename":"Fig22.png","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/fe477b12e6941999ef4d2444.png"},{"id":49768168,"identity":"5c31e5f6-77c2-4369-8a31-cd13cf7724fd","added_by":"auto","created_at":"2024-01-17 17:19:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":304646,"visible":true,"origin":"","legend":"\u003cp\u003eThe risk factors affecting overall survival were analyzed using multivariate Cox regression to assess the different parameters of CR at 4 (A) or 8 (B) weeks.\u003c/p\u003e","description":"","filename":"Fig32.png","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/852f334e46488ef0784d08ef.png"},{"id":49767136,"identity":"1d84b0fe-3d6c-4b55-afb0-8787bb51ec2e","added_by":"auto","created_at":"2024-01-17 17:11:37","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":518216,"visible":true,"origin":"","legend":"\u003cp\u003eThe directed acyclic graph shows that the effect of different treatments on OS was mediated by treatment responses, compared to the HLH-94 protocol at 4 (A) or 8 (B) weeks.\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/9f797076aa4815e22aa02108.png"},{"id":50681014,"identity":"2df04225-9641-4503-b903-93ecc4e267b0","added_by":"auto","created_at":"2024-02-05 16:54:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":829623,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/4b8838d4-38bf-4f70-a9fa-0953407e7ba7.pdf"},{"id":49767134,"identity":"2cd83f2c-e0da-40d5-a27e-a0a7e1b8856c","added_by":"auto","created_at":"2024-01-17 17:11:37","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":33744,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementarymaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-3862083/v1/da5a7a81af473415b5d22f9a.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Therapies and Treatment Responses for Hemophagocytic Lymphohistiocytosis in Children: A Single-center Retrospective Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eHemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease caused by an overactive immune response to antigens, resulting in uncontrolled activation of immune cells and cytokine storms[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. HLH-94 and HLH-04 guidelines have significantly improved the diagnosis of HLH and increased the survival rate. This multi-drug cocktail therapy is a practical pan-target therapeutic approach that acts on T cells/ macrophages by mainly inhibiting hyperinflammatory syndrome and/or hypertyrosinemia. However, due to the diseases\u0026rsquo; complexity and heterogeneity, many patients still do not respond well to it and experience a range of complications, which can ultimately lead to fatalities[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eExtracorporeal blood purification techniques, which involve a combination of plasma exchange and continuous renal replacement therapy, have been effectively utilized to eliminate inflammatory mediators and toxins of varying sizes while also providing support to the functions of multiple organs in cases of Epstein-Barr virus-HLH (EBV-HLH) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, there have not been enough studies to confirm this method of treating HLH. Therefore, it is important to identify effective therapeutic regimens for managing HLH and properly develop effective strategies for managing the condition through treatment response evaluation.\u003c/p\u003e \u003cp\u003eCausal mediation analysis: this methodology may be applied to analyze direct and indirect natural effects for almost any combination of variable types[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The total effect of the treatment comprises two parts: the indirect effect and the direct effect. Mediation analysis allows us to shift our focus from determining the effectiveness to understanding the mechanism of action[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. To explain how the intervention (in this case, e.g., HLH-94/04 protocol treatments) affects the outcome (overall survival) mainly mediated by mediators (complete remission at 4 or 8 weeks). These mediators could potentially serve as surrogate endpoints to provide better guidance for subsequent treatment.\u003c/p\u003e \u003cp\u003eTherefore, we conducted a study on 102 pediatric patients diagnosed with HLH at a single center. This study aimed to consider the clinical features of patients who underwent various therapies and assess the risk factors associated with their prognosis. Additionally, we used causal mediation analysis to examine whether the appropriate mediators mediated the effect of different treatments on Over Survival (OS), such as achieving complete disease remission at 4 or 8 weeks.\u003c/p\u003e"},{"header":"Patient and Method","content":"\u003cp\u003eA retrospective cohort study was conducted on individuals diagnosed with HLH at Zhujiang Hospital, Southern Medical University, from January 1, 2012, to December 31, 2022. The last follow-up time was May 1, 2023. The inclusion criteria of patients with HLH were the following: (1) patients aged\u0026thinsp;\u0026le;\u0026thinsp;18 years and (2) patients diagnosed with revised HLH-04 diagnostic criteria[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Patients whose outcome was not tracked during the survey and whose arrogance HLH was triggered by medical interventions or treatments that activate the immune system were excluded. Each patient collected demographic, clinical, and laboratory data including the following data: age, gender, family history, fever duration, presence of hepatomegaly, splenomegaly, lymphadenopathy, Laboratory data, treatment prescribed, and outcome. The laboratory diagnostic criteria for soluble CD25 levels (n\u0026thinsp;=\u0026thinsp;28) and natural killer cells (n\u0026thinsp;=\u0026thinsp;16) were only accessible to some patients with additional medical insurance. As a result, these data were not analyzed in this study. The HLH-94 and HLH-04 protocols were used to treat HLH [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Blood purification involves plasma exchange and/or continuous renal replacement therapy following diagnosis. Of the 35 patients, 6 underwent plasma exchange therapy alone, while the remaining 29 received both plasma exchange and continuous renal replacement therapy. Other treatments include corticosteroids, intravenous immunoglobulin, and/or ruxolitinib therapy. The study complied with the Declaration of Helsinki (revised in 2013) and was approved by the Institutional Review Board of Zhujiang Hospital, Southern Medical University (ID:2023-KY-258-01).\u003c/p\u003e \u003cp\u003eWe assessed therapeutic responses at 4 or 8 weeks and monitored dynamic responses based on response time and disease progression. Overall mortality was evaluated as death occurring during the follow-up period. The Early treatment response was defined as the resolution of all clinical manifestations and normalization of HLH-related laboratory findings either complete blood count or other HLH-related laboratory parameters at 4 or 8 weeks. Patients who meet the following criteria at 4 or 8 weeks will be classified as having achieved a complete response (CR): absence of fever, absence of splenomegaly, absence of cytopenia, absence of hypertriglyceridemia, ferritin levels below 500 \u0026#120583;g/L, and normal cerebral spinal fluid. A partial response (PR) is generally defined as an improvement of at least\u0026thinsp;\u0026ge;\u0026thinsp;2 symptoms and laboratory markers within two weeks after initiation of treatment. No response (NR) was considered a treatment failure and/or 50% worsening in two or more signs or laboratory abnormalities within 4 or 8 weeks[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eStatistical analysis\u003c/h3\u003e\n\u003cp\u003eDescriptive statistics (medians, ranges and standard deviations or standard errors) were used to summarize data. The Mann-Whitney U test or chi-square test was used to compare the differences between the two groups according to the category of variables. Univariate and multivariate Cox proportional hazards models evaluate the correlations among clinical data, laboratory variables, and outcomes. Statistical significance was defined as a two-tailed P value\u0026thinsp;\u0026lt;\u0026thinsp;0.05. The OS was measured as the time from HLH diagnosis to the date of death from any cause or the last follow-up.\u003c/p\u003e \u003cp\u003eCausal mediation analysis, a sophisticated epidemiological approach used to determine causal inference, explains the process through which the intervention (in this study, various treatments) affects the outcome (in this study, overall survival) through mediators (in this study, therapeutic responses) [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Therapeutic responses at 4 or 8 weeks as mediators were evaluated in this study. Baseline covariates in mediation analysis included Epstein-Barr virus (EBV) infection, central nervous system-HLH (CNS-HLH), splenomegaly, pediatric intensive care unit (PICU) admission, ferritin, lactate dehydrogenase (LDH), albumin (ALB), aspartate transferase (AST), total bilirubin (TBIL), and direct bilirubin (DBIL). The direct, indirect, and total effects of varied treatments on survival outcomes were estimated using mediation analysis[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. All statistical analyses were performed using SPSS version 26.0 (IBM, Armonk, NY) and R version 4.0.2.\u003c/p\u003e"},{"header":"Result","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Patients\u0026rsquo; characteristics in clinical and Laboratory\u003c/h2\u003e \u003cp\u003eIn this study, 102 patients were enrolled. Of these, 31 patients (30.4%) underwent the HLH-94 protocol treatment, while 22 (21.6%) received the HLH-04 protocol. Additionally, 35 patients underwent blood purification in the PICU, with 13 receiving blood purification alone and the remaining 22 receiving blood purification in combination with HLH-94/04 protocol treatment (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe male-to-female ratio in the study was 1.55 (62:40) as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The median age of patients with HLH was 3 years, with 49.02% being younger than 2 years and only 5.88% being older than 10 years. Five patients were diagnosed with primary HLH and were found to have specific gene mutations by Sanger sequencing, including X-linked lymphoproliferative Disease Type 1 (XLP1), X-linked lymphoproliferative syndrome-2 (XLP2), Magnesium transporter 1 (MAGT1), Unc-13 Homolog D (UNC13D), and SH2 Domain Containing 1A (SH2D1A). Fever was the most common symptom experienced by patients (98.0%), along with high ferritin levels. Additionally, some patients also exhibited splenomegaly (67.8%) and CNS involvement (12.8%). The level of sIL-2R/sCD25 ranged from 1686 to 108360 \u0026micro;/ml. Natural killer cell activity was reduced or absent in six patients.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and clinical characteristics among patients with HLH\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAll (n\u0026thinsp;=\u0026thinsp;102)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHLH-94 protocol treatment (n\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHLH-04 protocol treatment (n\u0026thinsp;=\u0026thinsp;22)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBlood purification alone(n\u0026thinsp;=\u0026thinsp;13)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBlood purification and HLH-94/04 protocol (n\u0026thinsp;=\u0026thinsp;22)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eOther treatments\u003csup\u003ea\u003c/sup\u003e (n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender, male, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62 (60.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (64.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10 (45.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9 (69.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e13 (59.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e10 (71.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.488\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, y, median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3 (0.2,18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (0.4,15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2(0.8,13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (0.3,8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3 (0.2,9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2 (0.2,18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.465\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePrimary HLH\u003c/b\u003e, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5 (4.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(9.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2(9.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.394\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSecondary HLH\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEBV infection, and (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68 (66.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (74.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15 (68.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6 (46.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16 (72.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8 (57.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.378\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther infections, and (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (5.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (3.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (15.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2 (9.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 (7.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.362\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMalignancies, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (2.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (3.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (4.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.735\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAutoimmune diseases, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1 (3.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (4.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (7.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 (7.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.766\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnknown, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17 (16.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (6.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (27.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (30.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (4.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4 (28.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.045\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHLH-04 criteria\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFever, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100 (98.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 (90.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e22 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e14 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.115\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSplenomegaly, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69 (67.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (74.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16 (72.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9 (69.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e13 (59.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8 (57.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.677\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBicytopenia, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e76 (74.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (74.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17 (77.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9 (69.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16 (72.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e11 (78.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.979\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertriglyceridemia and/or hypofibrinogenemia, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e82 (80.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24 (80.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18 (81.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12 (92.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17 (81.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e11 (78.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.887\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFerritin, \u0026micro;g/L, median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16826\u003c/p\u003e \u003cp\u003e(568, 177730)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8178\u003c/p\u003e \u003cp\u003e(568,73435)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12748 (906,90309)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11335\u003c/p\u003e \u003cp\u003e(1324,83027)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e25970\u003c/p\u003e \u003cp\u003e(1846,177730)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e37191.5 (1734,80287)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.007\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemophagocytosis, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e93 (91.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19 (86.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e19 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e11 (78.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.082\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eH Score, median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e270 (141,319)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e257 (171,319)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e268 (141,319)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e269 (174,319)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e289 (239,319)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e266 (244,304)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.109\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCNS involvement, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (12.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (6.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (4.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (15.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8 (36.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.004\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of onset to diagnosis, d, median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11(1,48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11(5,41)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (3,48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11(4,42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8.5(2,35)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12 (1,32)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.128\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePICU, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e78 (76.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 (67.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14 (63.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e21 (95.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e9 (64.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.012\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of PICU, d, median (range)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (0,49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (0,37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.5 (0,26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9 (0,18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14 (0,49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e3.5 (0,33)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e0.002*\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAssessment of Response, n (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCR at 4 weeks\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 (57.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24 (77.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19 (86.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (15.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e8 (36.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6 (42.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCR at 8 weeks\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54 (52.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22 (71.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17 (77.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (15.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7 (31.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6 (42.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"8\" nameend=\"c8\" namest=\"c1\"\u003e \u003cp\u003e\u003csup\u003ea\u003c/sup\u003eOther treatments include corticosteroids, intravenous immunoglobulin therapy, and/or ruxolitinib therapy. Abbreviations: HLH: hemophagocytic lymphohistiocytosis; EBV, Epstein-Barr virus; PICU, Pediatric Intensive Care Unit; CNS, Central nervous system; CR: complete response. * p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe CR rates of HLH patients at 4 weeks and 8 weeks were 57.8% and 52.9% respectively. HLH-04 regimen had a better CR rate of 86.4% at 4 weeks compared to the HLH-94 regimen at 77.4%. Blood purification alone or with the HLH-94/04 regimen had lower CR rates at 4 weeks at 15.4% and 36.4% respectively. However, patients in these two groups had higher levels of central infiltration, ferritin, and bilirubin than the HLH-94/04 treatment group. Additionally, they had higher rates of PICU treatment and longer PICU stays (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Supplementary Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe 10-year overall survival rate for HLH was 54.3%. Among the various treatment protocols, the HLH-94/04 protocol demonstrated the highest survival rates at 81.3% and 76.6%, respectively. However, when blood purification was administered alone or in combination with the HLH-94/04 protocol, the survival rates were significantly lower, at 15.4% and 23.4%, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Patients who achieved CR at 4 or 8 weeks had a higher survival rate of 90.7% and 92.3%, respectively. On the other hand, patients who partially responded or did not respond at 4 or 8 weeks had a significantly lower survival rate of 2.9% and 3.4%, respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Prognostic factors by Cox regression\u003c/h2\u003e \u003cp\u003eAccording to the results of the univariate Cox regression analysis, various risk factors contributing to overall mortality were found, such as EBV infection, splenomegaly, CNS involvement, admission to the PICU, elevated levels of ferritin, AST, LDH, TBIL, DBIL, different treatments, and CR at 4 or 8 weeks (refer to Supplementary Table S2).\u003c/p\u003e \u003cp\u003eAfter performing COX regression analysis and adjusting for multiple variables, it was determined that patients with central nervous system involvement and elevated LDH levels faced a higher risk of mortality in HLH. These factors were found to be independently significant prognostic risk factors for the parameters of CR at 4 or 8 weeks (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In comparison to the HLH-94 protocol treatment, it was observed that blood purification alone or other treatments were associated with an increased risk of death. Conversely, the HLH-04 protocol treatment showed an increased risk of death, although it did not reach statistical significance. Furthermore, the combination of blood purification with the HLH-94/04 protocol treatment decreased the risk of death, but this finding was not statistically significant.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Causal mediation analysis\u003c/h2\u003e \u003cp\u003eSince the patients who received various treatments displayed different early treatment responses and OS, we investigated whether CR at 4 or 8 weeks was the primary mediator of the treatment effect on OS (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Our mediation analysis revealed that, compared to the HLH-94 protocol treatment, the HLH-04 protocol treatment did not have a significant mediating effect on patient OS (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Blood purification has been shown to have indirect and direct effects on decreasing patient overall survival (OS), with a mediating effect of 33.28% at 4 weeks and 26.56% at 8 weeks. Blood purification combined with the HLH-94/04 protocol treatment showed that CR at 4 or 8 weeks mediated a major effect of 79.88% or 51.95% on patient OS, but the direct effect was insignificant (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Furthermore, the percentage of mediating effects decreased in CR at 8 weeks compared to CR at 4 weeks. CR at 4 weeks may be a better mediator in the OS treatments than CR at 8 weeks.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eHLH is a severe syndrome characterized by hyperinflammation and aberrant immune activation. The cytokine storm is a crucial factor in the pathogenesis of various hematological disorders. Underlying defects from primary genetic dysfunction or other etiologies that enable sustained activation of cytotoxic T cells are the core immunological features and pathogenesis of HLH[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Previous reports in adult patients showed that patients with disseminated intravascular coagulation, nosocomial infections and neurological symptoms had statistically significantly worse survival[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. In pediatric patients with secondary HLH/MAS, thrombocytopenia was a predictor of mortality. This study of the pediatric population found that CNS involvement and elevated LDH levels were independent prognostic factors. Children and adults with HLH have different prognostic factors and require distinct treatment strategies[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe effectiveness and safety of blood purification have been reported in a small sample of patients with HLH [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In our study, the blood purification alone group fails to induce disease remission and increases the associated risk of death. This lack of improvement may be attributed to the potential side effects of blood purification treatment, such as coagulation disorders and fluctuations in drug concentration. These side effects counteracted the therapy's intended effects of supporting organ function and reducing inflammatory factors[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Nevertheless, it is worth mentioning that blood purification therapy may hold therapeutic advantages for patients with HLH combined with liver failure[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Blood purification treatment may be considered a supportive measure in cases where patients do not respond to HLH-1994 or HLH-2004 treatment or experience organ failure[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. However, further research is necessary to fully understand its potential benefits and limitations. Blood purification combined with the HLH-94/04 protocol treatment may be more effective in improving long-term survival rates than using blood purification alone. However, due to the small sample size, it did not show significant improvement compared to the HLH-94 protocol treatment. Furthermore, according to our causal analysis, blood purification combined with chemotherapy has shown a 79.88% effectiveness in inducing disease remission compared to HLH-94, suggesting that it may be beneficial in inducing disease remission.\u003c/p\u003e \u003cp\u003eIn our study, the CR rates at 4 and 8 weeks of the HLH-94/04 protocol treatments were higher than those of blood purification alone or combined with the HLH-94/04 protocol treatments, resulting in a better survival rate. In other studies of children and adults with non-malignancy-related secondary HLH, lack of response at 8 weeks was the strongest predictor of poor OS [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Our study revealed that achieving CR at 4 or 8 weeks independently influenced the prognosis of HLH. Interestingly, we observed that the mediation effect of achieving CR at 4 weeks was more pronounced compared to achieving CR at 8 weeks. This suggests that achieving CR at 4 weeks may be a more appropriate mediator in impacting OS. Currently, there are few available data on whether patients who switch to a salvage regimen after the 4-week assessment have better survival rates than those who continue treatment. Based on the latest TPOG NHL protocol, patients who didn't respond to initial treatment at 4 weeks or experienced a relapse would receive more intensive chemotherapy and stem cell transplantation[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Early response assessment may predict a poor prognosis, which emphasizes the need to start salvaging treatment and quickly prepare for hematopoietic stem cell transplantation. This proactive approach can greatly contribute to maintaining stability and the patient's life [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Furthermore, an early response to treatment may serve as a substitute endpoint for modifying subsequent treatment.\u003c/p\u003e \u003cp\u003eThe study was conducted retrospectively, and the smaller number of patients in each treatment group may have introduced some bias into the results. Further prospective randomized controlled studies with large sample sizes are necessary to assess the potential benefits of blood purification therapy as a management strategy for HLH. Additionally, it is essential to determine whether 4-week or 8-week CR assessments are suitable for guiding subsequent intensive therapy or transplantation with hematopoietic stem cell transplantation.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, the HLH-94/04 protocol treatments are considered the standard treatment for HLH. However, blood purification alone may not be beneficial, and the potential benefits of using it in combination with the HLH-94/04 protocol for managing HLH are still being investigated and require further study. Achieving complete remission at 4 weeks, as compared to 8 weeks, maybe a more suitable factor in overall survival. This distinction is crucial in determining the most effective treatment strategies and significantly impacts survival rates and prognosis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe express our gratitude to the Department of Pediatric Hematology, the Department of Pediatric Surgery, and the Department of Pediatric Intensive Care Unit for their participation in our study, provision of data, and outstanding collaboration. We also thank Professor Chengfeng Zhang and Professor Peihua Cao for their help with statistical analysis. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLH Y and DA L conceptualized and designed the study, drafted the initial manuscript, and provided critical review and revisions. LW, LL H, XL, YJ Z, JZ, JG Z, XL, LC L, and GM Z contributed to the data collection, conducted the initial analyses, and also provided critical review and revisions. LC Y also provided critical review and revisions. LH Y coordinated and supervised the data collection and provided critical review and revisions for important intellectual content. All authors contributed to the article, approved the submitted version, and played a significant role in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that the research was carried out without commercial or financial interests that could be seen as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was approved by the Institutional Review Board of Zhujiang Hospital, Southern Medical University (ID:2023-KY-258-01).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent from the participant\u0026rsquo;s legal guardian/next of kin was not required to participate in this study in accordance with the national legislation and the institutional requirements.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets utilized and/or analyzed during the current study can be obtained from the corresponding author upon reasonable request. Requests may be sent to [email protected].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that they did not receive any funds, grants, or other support during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors and Affiliations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDepartment of Pediatric Hematology, Zhujiang Hospital, Southern Medical University, Guangzhou, China\u003c/p\u003e\n\u003cp\u003eLihua Yu, Danna Lin, Li Wu, Lulu Huang,\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eXiaorong Lai, Yajie Zhang, Juan Zi, Jingxin Zhang, Xu Liao, Lichan\u0026nbsp;Liang, Guanmei Zhang, Liucheng Yang, Lihua Yang\u003c/p\u003e\n\u003cp\u003eDepartment of Pediatric Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China\u003c/p\u003e\n\u003cp\u003eLiucheng Yang\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence to Liucheng Yang and Lihua Yang\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCanna SW, Marsh RA. 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Recommendations for the Use of Etoposide-Based Therapy and Bone Marrow Transplantation for the Treatment of HLH: Consensus Statements by the HLH Steering Committee of the Histiocyte Society. J Allergy Clin Immunol Pract. 2018;6(5):1508-17. doi: 10.1016/j.jaip.2018.05.031.\u003c/li\u003e\n\u003c/ol\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":"Hemophagocytic Lymphohistiocytosis, Pediatric, Mediation Analysis, Blood Purification, Treatment Responses","lastPublishedDoi":"10.21203/rs.3.rs-3862083/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3862083/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHemophagocytic lymphohistiocytosis (HLH) is a severe and life-threatening systemic inflammatory disorder. This retrospective study aims to evaluate the effectiveness of different therapies and identify early treatment responses maybe for indicators to overall survival. The study involved 102 patients from January 1, 2012, to December 31, 2022, using Cox regression to identify prognostic risk factors. Causal mediation analysis assessed the impact of various treatments on overall survival through the mediator of complete remission at 4 or 8 weeks. Achieving complete remission at 4 or 8 weeks suggests a favorable prognosis. However central nervous system involvement, high lactate dehydrogenase levels, and blood purification alone indicate poor prognosis (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). HLH-94/04 protocol treatments had higher survival rates at 81.3% and 76.6%, compared to blood purification alone or combined with HLH-94/04 protocol treatments at 23.4% and 15.4%. Complete remission at 4 or 8 weeks resulted in higher survival rates of 90.7% and 92.3% respectively, compared to 2.9% and 3.4% for partial or no response. Compared to HLH-94 protocol treatment, blood purification alone has a 33.28% effect mediated by inducing complete remission at 4 weeks, which decreases to 26.56% at 8 weeks. Blood purification combined with HLH-94/04 protocol treatment with a higher mediation effect was 79.88% at 4 weeks compared to 51.95% at 8 weeks. HLH-94/04 protocol treatments led to complete remission and improved survival rates than Blood purification alone or combined with HLH-94/04 protocol treatment. Complete remission at 4 weeks may be a better mediator of overall survival than that at 8 weeks.\u003c/p\u003e","manuscriptTitle":"Therapies and Treatment Responses for Hemophagocytic Lymphohistiocytosis in Children: A Single-center Retrospective Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-17 17:11:32","doi":"10.21203/rs.3.rs-3862083/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":"4e3dd022-00c9-4f56-a5ea-0abd01ad7b51","owner":[],"postedDate":"January 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-02-05T16:46:29+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-17 17:11:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3862083","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3862083","identity":"rs-3862083","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}