A study of the correlation of Fraction of exhaled Nitric Oxide (FeNO) with Absolute Blood Eosinophil Count (AEC) in Indian children to establish its utility in prediction of control and exacerbation of Bronchial Asthma

A study of the correlation of Fraction of exhaled Nitric Oxide (FeNO) with Absolute Blood Eosinophil Count (AEC) in Indian children to establish its utility in prediction of control and exacerbation of Bronchial Asthma | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 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Data may be preliminary. 17 November 2025 V1 Latest version Share on A study of the correlation of Fraction of exhaled Nitric Oxide (FeNO) with Absolute Blood Eosinophil Count (AEC) in Indian children to establish its utility in prediction of control and exacerbation of Bronchial Asthma Authors : Harshita Chaudhary , Bal Mukund , Vivek Bhat , and Gaurav Mahajan Authors Info & Affiliations https://doi.org/10.22541/au.176339531.12414468/v1 160 views 67 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract ¿p#1 Background Asthma and Allergic Rhinitis (AR) are common in children and often coexist, reinforcing the “unified airway” model. Biomarkers like FeNO and AEC are valuable in assessing Type-2 inflammation. American Thoracic Society /European Respiratory Society guidelines endorse Paediatric FeNO cut-offs (35 ppb high) for control and exacerbation risk, yet no Indian reference values exist. We aimed to correlate FeNO and AEC to establish clinically relevant Indian cut-offs in Paediatric asthma with Allergic Rhinitis. Objectives To evaluate correlation between FeNO and AEC in children with asthma and AR, and to establish Indian cut-off values for differentiating control and exacerbation. Methods A prospective cohort study was conducted on 101 children (4–12 years) with asthma and Allergic rhinitis . FeNO and AEC were measured at baseline, one month, and three months. Results FeNO correlated significantly with AEC during asthma (r=0.361, p=0.003) and AR exacerbations (r=0.534, p20.5 ppb showed specificity 81%, sensitivity 77%, PPV 52.6%, NPV 92.6% (p<0.0001); corresponding AEC was 505 cells/µl (specificity 80%, sensitivity 73%, PPV 50%, NPV 91.6%). For asthma control, FeNO <14.5 ppb demonstrated specificity 87%, sensitivity 55%, PPV 44.9%, NPV 71% (p<0.0001); corresponding AEC was 413 cells/µl (specificity 81%, sensitivity 49%, PPV 47.8%, NPV 74.8%). Conclusion This is first Indian study that defines practical FeNO and AEC cut-offs for children with asthma and Allergic Rhinitis. FeNO >20.5 ppb (AEC 505 cells/µl) indicates exacerbation, while FeNO <14.5 ppb (AEC 413 cells/µl) indicates control. These thresholds may guide clinical decision-making in Indian practice. Key message: FeNO values to predict asthma exacerbations and asthma control for Indian children are different from rest of the world. The study defines valuable thresholds which should be validated by carrying out more research in developing world rather than using European or American FeNO values. ¿p#1 A study of the correlation of Fraction of exhaled Nitric Oxide (FeNO) with Absolute Blood Eosinophil Count (AEC) in Indian children to establish its utility in prediction of control and exacerbation of Bronchial Asthma Dr Harshita Chaudhary, Dr Hardeep Kaur, Dr Sateesh R, Dr Bal Mukund, Dr Vivek Bhat, Dr Gaurav Mahajan ¿p#1 Keywords- Fraction of exhaled nitric oxide, Absolute Eosinophil Count, American Thoracic Society, European Respiratory Society, Bronchial Asthma, Allergic Rhinitis, Global Initiative for Asthma ¿p#1 Abstract ¿p#1 Background Asthma and Allergic Rhinitis (AR) are common in children and often coexist, reinforcing the “unified airway” model. Biomarkers like FeNO and AEC are valuable in assessing Type-2 inflammation. American Thoracic Society /European Respiratory Society guidelines endorse Paediatric FeNO cut-offs (35 ppb high) for control and exacerbation risk, yet no Indian reference values exist. We aimed to correlate FeNO and AEC to establish clinically relevant Indian cut-offs in Paediatric asthma with Allergic Rhinitis. ¿p#1 Objectives To evaluate correlation between FeNO and AEC in children with asthma and AR, and to establish Indian cut-off values for differentiating control and exacerbation. ¿p#1 Methods A prospective cohort study was conducted on 101 children (4–12 years) with asthma and Allergic rhinitis . FeNO and AEC were measured at baseline, one month, and three months. ¿p#1 Results FeNO correlated significantly with AEC during asthma (r=0.361, p=0.003) and AR exacerbations (r=0.534, p20.5 ppb showed specificity 81%, sensitivity 77%, PPV 52.6%, NPV 92.6% (p<0.0001); corresponding AEC was 505 cells/µl (specificity 80%, sensitivity 73%, PPV 50%, NPV 91.6%). For asthma control, FeNO <14.5 ppb demonstrated specificity 87%, sensitivity 55%, PPV 44.9%, NPV 71% (p<0.0001); corresponding AEC was 413 cells/µl (specificity 81%, sensitivity 49%, PPV 47.8%, NPV 74.8%). ¿p#1 Conclusion This is first Indian study that defines practical FeNO and AEC cut-offs for children with asthma and Allergic Rhinitis. FeNO >20.5 ppb (AEC 505 cells/µl) indicates exacerbation, while FeNO <14.5 ppb (AEC 413 cells/µl) indicates control. These thresholds may guide clinical decision-making in Indian practice. ¿p#1 Key message: FeNO values to predict asthma exacerbations and asthma control for Indian children are different from rest of the world. The study defines valuable thresholds which should be validated by carrying out more research in developing world rather than using European or American FeNO values. ¿p#1 INTRODUCTION Asthma is a chronic debilitating disease affecting nearly 7 million children globally. (1) Allergic rhinitis is frequently a comorbidity with asthma and affects nearly 40% of children (2) .Global prevalence of childhood asthma is 10.2% (3) while in Indian scenario, childhood asthma prevalence is 3.3% (4) and of allergic rhinitis is 20-30 % (5,6) . In Indian children, both Allergic Rhinitis and Bronchial Asthma are commonly encountered. The Global Asthma Network (GAN) study reported that despite the presence of symptoms of severe asthma, accurate diagnosis is not established leading to underdiagnosis and undertreatment in Indian setting (6) FeNO has been identified to be elevated in children with both asthma and allergic rhinitis and is a good indicator to determine their exacerbation (7) . FeNO is typically measured using standardized single-breath techniques at regulated expiratory flow rates and is feasible even in children above four years of age (8,9) . The availability of portable analysers has facilitated its broader use in outpatient pediatric care (8) . Elevated FeNO levels are commonly observed in atopic asthmatic children and correspond with underlying Th2-mediated eosinophilic airway inflammation (7,10,11) . Significant correlations have been demonstrated between FeNO and eosinophil counts in blood, induced sputum, and bronchoalveolar lavage samples from atopic pediatric populations (12) . As per 2011 guidelines issued by the American Thoracic Society (ATS), FeNO has been recognised as a diagnostic aid for identifying eosinophilic airway inflammation and evaluating corticosteroid responsiveness (8) . ATS-based thresholds propose that FeNO values below 20 ppb in children are suggestive of a low likelihood of eosinophilic inflammation and steroid responsiveness whereas levels above 50 ppb indicate a high probability of both. The coexistence of systemic eosinophilia further enhances FeNO’s diagnostic relevance. Malinovskyi et al. demonstrated that children with elevated FeNO (≥35 ppb in <12 years, ≥50 ppb in ≥12 years) and high eosinophil counts had a significantly increased likelihood of current asthma (adjusted odds ratio 5.41 vs. 2.41 for FeNO alone), as well as increased risks of wheezing, asthma attacks, and emergency visits (13) . FeNO and blood eosinophil count (BEC) are complementary biomarkers of type 2 inflammation in pediatric asthma, reflecting airway nitric oxide and systemic eosinophilia. Studies report moderate–strong correlations, especially in steroid-naïve, atopic, or allergic rhinitis children, aiding non-invasive assessment of inflammation, disease severity, and risk of poor control or exacerbations (14-18) . Despite extensive global literature, there remains a significant gap in Indian data regarding FeNO’s role in pediatric asthma especially in children with comorbid allergic rhinitis which affects nearly 50% of this population. Importantly ethnicity, anthropometry, and environmental exposures influence FeNO levels yet population-specific reference cut-offs for Indian children are lacking. Additionally, the potential of FeNO to predict exacerbations or guide corticosteroid therapy in Indian settings remains underexplored. The present study aims to bridge these knowledge gaps by assessing the association between FeNO and blood eosinophil levels in Indian children diagnosed with asthma and allergic rhinitis. The study also seeks to identify a FeNO threshold that could reliably indicate risk of poor asthma control or exacerbation. In this prospective cohort study, we evaluated Indian children with asthma and allergic rhinitis for the exhaled FeNO cut off and studied the correlation with Absolute eosinophil count (AEC). ¿p#1 METHODS This was an observational cohort study in which we enrolled 101 children between 4 to 12 years of age presenting with symptoms fulfilling our case definitions of Asthma and Allergic rhinitis. Study duration was from March 2023 to December 2024 at a tertiary care hospital in Western India. An institutional ethics committee (IEC) approval was taken with IEC approval number 91, dated 01 March 2023. The IEC constituted at our hospital, INHS Asvini was a seven member committee which provided approval to our research proposal after careful scrutiny of study design and ethics related issues. We defined asthma exacerbation and control as per GINA guidelines 2023 (19) and allergic rhinitis as per Allergic Rhinitis and its impact on asthma (ARIA) guidelines 2016 (2) . Inclusion criteria : Children with both Allergic Rhinitis and Bronchial Asthma aged 4yr-12yrs. Exclusion criteria : (a) Wheezing explained by etiology other than Bronchial Asthma (b) Deviated nasal septum/structural nasal cavity defects. After obtaining well informed written consent, data on demographic variables including age of onset, frequency of symptoms, frequency and details of previous asthma exacerbation, triggers, seasonality, family history of atopy, exposure to smoking/known allergens, immunization status, comorbidities and anthropometry as per WHO assessment charts were extracted on a predesigned proforma. We measured FeNO values and Eosinophil count on first visit, then after one month and then again after 3 months. All cases were assessed for current symptoms, vital parameters. In case of asthma exacerbation, FeNO and eosinophil count values were calculated within 6 hours of exacerbation. FeNO values were calculated by using FENOM PRO TM Asthma Monitor. Patient preparation – Children were asked not to take any green leafy vegetables, milk or protein rich food in the morning in order to avoid false positive FeNO values. Children were also advised to avoid exercising and excessive running 2 hrs prior to testing. Children who were on inhaled corticosteroids were advised for drug abstinence (Short acting β agonist for 4 hours, Long acting β agonist for 24 hrs). To measure FeNO, child was asked to exhale for 6 seconds and a total of three recordings were taken. FeNO value was taken as mean of these three recordings. On every visit both FeNO values and Eosinophil Counts were calculated and management was provided as per clinical status. ¿p#1 STATISTICAL ANALYSIS ¿p#1 All the data was noted down in a pre-designed study proforma. Qualitative data was represented in the form of frequency and percentage. Association between qualitative variables was assessed by Chi-Square test with Continuity Correction for all 2 X 2 tables and Fisher’s exact test for all 2 X 2 tables. Quantitative data was represented using Mean ± SD. Analysis of Quantitative data between the two groups was done using unpaired t-test if data passed ‘Normality test’ and by Mann-Whitney Test if data failed ‘Normality test’. Pearson’s correlation coefficient was used to compute correlation between FeNO and BEC. A p-value < 0.05 was taken as level of significance. Results were graphically represented where deemed necessary. SPSS Version 26.0 was used for most analysis and Microsoft Excel 2021 for graphical representation. ¿p#1 RESULTS: We enrolled 101 case records of which 4 were lost to follow up. 1. Demography and family history Mean age in our study was 7.3 ± 2.2 year with male dominance (62.4%). Rest data depicted in Table 1 . Family history of atopy and allergy was recorded in 72.3% of children. Concomitant allergic dermatitis and conjunctivitis were evident in 35.6% and 17.8% of children respectively. ¿p#1 2. Allergic Rhinitis profile Sneezing (91.1%) was most common symptom at the initiation of rhinitis. Allergic rhinitis was seasonal and perennial in 70.3% and 29.7% of children. For the current medical visit, we identified viral illness as the most common trigger (96%) depicted in Table 2. ¿p#1 3. Examination findings: Pale nasal mucosa (91.1%), hypertrophy of inferior turbinate (77.2%) were seen commonly in study participants. Among the clinical signs, allergic salute (83.2%) and allergic shiners (79.2%) were commonly observed as mentioned in Table 3 . 4. Details of previous asthma exacerbations The mean age at previous asthma exacerbation was 6.3±2.0 years. In majority of the children, it lasted for 4 days (45.9%). URTI (96%) was the most common trigger. Concurrent Allergic rhinitis was present in 73.5% of children. Hospitalization was necessary for 21.4% of children. Exacerbation was managed with Levo-salbutamol MDI, corticosteroids, and nebulization. ¿p#1 5. Comparison of FeNO and absolute eosinophil count among patients with or without exacerbation at baseline and follow-up In our study, both FeNO and AEC were significantly higher in children with exacerbation than those without exacerbation. We observed that there was significant positive correlation between FeNO and AEC during Bronchial Asthma (r=0.361, p=0.003) and Allergic Rhinitis (r=0.534, p20.5 ppb was found to be statistically significant with specificity of 81%, sensitivity of 77%, positive predictive value of 52.6 % and negative predictive value of 92.6% with p value of <0.0001 Absolute Eosinophil Count corresponding to same FeNO value was 505 cells/µl with specificity of 80%, sensitivity of 73%, PPV of 50% and NPV of 91.6% with p value of <0.0001 Similarly for Asthma control, FeNO value <14.5 ppb was found to be statistically significant with specificity of 87%, sensitivity of 55%, positive predictive value of 44.9% and negative predictive value of 71% with p value of <0.0001 Absolute Eosinophil Count corresponding to same FeNO value was 413 cells/µl with specificity of 81%, sensitivity of 49%, PPV of 47.8 % and NPV of 74.8% with p value of <0.0001 . ¿p#1 DISCUSSION: Data of total enrolled 101 patients, was analyzed, interpreted and results were obtained. Demographic parameters Majority of the children had onset of asthma and allergic rhinitis below the age of 6 years (87.1% and 66.3%) with mean age at onset 4.8±1.4 years and 5.6±1.9 years, respectively. Asthma and Allergic rhinitis were seen as early as 2 years and 3 years respectively. In our study mean age was 7.3 yrs. which was younger as compared to study done by Kim et al. where mean age of the Allergic rhinitis with asthma group children was 9.6 year and 9.2 years, respectively (20) . Masuda et al. included children aged 2 to 10 years and reported that the median age of onset of asthma and rhinitis in children was 2.8 years and 2.9 years which was comparable to our study (21) . It is important to understand the age of onset of asthma can impact the severity of asthma. Khalaf et al. demonstrated that in children who had onset of asthma between 5 to 8 years, there were more numbers of exacerbation and delayed diagnosis was common compared to older children (22) . In our study, 62.4% children were boys and 37.6% were girls. As per Global Asthma Study done by Sheetu et al (6) found that prevalence of asthma exacerbation was more among boys (3.64%) than girls (2.63%) in 6-7 yrs. age group and in adolescent phase prevalence was 4.43% in boys and 2.43% in girls. ¿p#1 Family history Family history of atopy/allergy was recorded in 72.3% of children. Concomitant allergic dermatitis and conjunctivitis were evident in 35.6% and 17.8% of children, respectively. Nair et al. studied 101 children with acute asthma and identified 72.3% children with family history of atopy which was comparable to our study (23) . ¿p#1 Allergic Rhinitis Sneezing (91.1%), nasal block (64.4%), rhinorrhea (59.4%), perineal cough (29.7%) and itchy watery eyes (32.7%) were the common symptoms of Allergic Rhinitis. Among the clinical signs, allergic salute (83.2%) and allergic shiners (79.2%) were commonly observed. Wheezing was seen in 46.5% of children. In a study from Bangalore, India, Singh et al. reported that sneezing (81.2%), nasal obstruction (70.6%), rhinorrhea (64.7%), and nasal itching (40.5%) were commonly recorded symptoms of rhinitis which was comparable to results of our study (6) . AR was seasonal and perennial in 70.3% and 29.7% of children. For the current medical visit, we identified viral illness as the most common trigger (96%) followed by cold (87.1%) and dust exposure (36.6%), pet exposure (8.9%) and smoke exposure (4.0%). For seasonal allergic rhinitis, pollens and weeds are the primary triggers in majority of cases whereas house dust mites, pets, and molds cause perennial rhinitis. A study from Nair et al . reported that in 101 children with acute exacerbation, cold climate (67.3%) was most common trigger followed by infections (16.8%) and vigorous activity (21.8%) (23). 28.7% having different risk factors such as strong odour, pets, smoke and pollens (23) . ¿p#1 Details of bronchial asthma exacerbations The mean age at previous exacerbation was 6.3±2.0 years. In majority of the children, it lasted for 4 days (45.9%). URTI (96%) was the most common trigger. Hospitalization was necessary for 21.4% of children. Exacerbation was managed with MDI and corticosteroids. Good treatment compliance was noted in 77.6% population however at first contact visit (baseline) acute exacerbation can be attributed to new episode triggered by high incidence of viral infections (96%). Yavuz et al. identify that acute asthma exacerbation is one of the most encountered emergencies in children. Among 348 children, 19.3% had severe acute exacerbation. It was responsible for significantly higher rates of hospitalization. Lack of regular asthma control therapy was one of the important contributors to exacerbations. Thus, good compliance to therapy is necessary to control the exacerbations (24) . At first visit, most children were on MDI Levosalbutamol (50.4%) and only 28.2% children were on inhaled corticosteroids. Steroids are essential components of the treatment of acute exacerbations along with SABA. Payares‐Salamanca et al (25) . conducted a meta-analysis that involved 15 studies with 2057 participant children in which use of MDI was associated with better improvement in asthma symptoms. As per GINA guidelines, inhaled corticosteroids are mainstay treatment, in view of which in our study too we used MDI and inhaled corticosteroids for treatment (19) . We observed that at baseline, 52.5% and 38.6% of children were in acute exacerbation of asthma and allergic rhinitis respectively. These high rates could be because of high incidence of viral infection (97%). These proportions dropped sequentially over 3 months (Table 4) demonstrating the treatment effectiveness. FeNO, Absolute eosinophil count and Asthma Exacerbations: Asthma is one of the common chronic airway diseases in children that is associated with eosinophilic inflammation. FeNO is a non-invasive test that provides objective information about the airway inflammation. Also, in patients with allergic rhinitis, especially highly reactive cases, there is increased nasal nitric oxide indicating airway inflammation. Sivan et al. found that children with FeNO levels of >23 ppb are very likely to have asthma, the false positive rate being sensitivity of 86%, specificity of 89%, positive predictive value of 92% and negative predictive value of 80% (11) . In our study, the cut-off levels of FeNO associated with acute asthma exacerbations was 20.5 ppb with 77% sensitivity and 81% specificity with PPV 52.7% and NPV 92.6% (Table 5). A study by Raj et al. from New Delhi, India included 243 asthmatic children and identified that FeNO levels increase during the exacerbation compared to their perfect FeNO levels. The cut off of 20 ppb was found to have 44% sensitivity and 68.7% specificity for bronchial asthma acute exacerbations (26) . From these studies, it is clear that cut-off levels of FeNO in predicting asthma exacerbation vary widely. However, for Indian children, FeNO >20.5 ppb can predict hyperactivity of the airway and thereby exacerbations. Any child with FeNO <20.5 ppb may not likely experience exacerbations. In our study, Absolute eosinophil count cut-off corresponding to FeNO value of 20.5 ppb is identified to be 505 cell/µL to predict the asthma exacerbations with a sensitivity and specificity of 73% and 80%, PPV 50%, NPV 91.6% respectively. (Table 5) A metanalysis evaluating the role of blood eosinophil count in predicting asthma exacerbation, Mallah et al. demonstrated that there was 1.3 times greater risk of asthma exacerbation with increased eosinophil counts. This association was persistent in children’s studies as well (27) . Krantz et al. studied children from United Kingdom and reported that FeNO is 4.4% higher in current allergic rhinitis. Perennial sensitization was associated with higher FeNO. In our studies too, we observed FeNO>20.5 ppb and AEC > 505 cells/ul were associated with uncontrolled allergic rhinitis (28) . FeNO , Absolute eosinophil count and Asthma control In our study, we observed that FeNO and AEC cut-off values of 14.5 ppb and 413 cells/µL to be associated with asthma control (Table 5). ¿p#1 Correlation of FeNO and AEC during asthma exacerbations and control We observed that there was significant positive correlation between FeNO and AEC during asthma (r=0.361, p=0.003) exacerbations. The same was also seen during asthma (r=0.292, p=0.036) control (Figure 1). A study by Habis et al. reported that FeNO levels were significantly higher in patients with eosinophil counts ≥300 cells/μL (p=0.012) and correlated positively with bronchodilator responsiveness (r=0.38, p=0.001). Study established the role of FeNO and eosinophil count as valuable complementary biomarkers in asthma control (29) . Meena et al. (30) studied 156 uncontrolled/partly controlled and 51 controlled children; FeNO medians 16 vs 13 (p=0.26), though without identifying FeNO cutoffs. Blood and sputum eosinophil count, serum allergen specific IgE levels, FeNO, periostin levels are few biomarkers available to assess severity of asthma. Biomarker based asthma diagnosis in children is not popular in Indian setting due to non-availability of these biomarkers and lack of training of Physicians/Paediatricians. FeNO is an established biomarker in adult asthmatic patients. However, FeNO has emerged as a convenient, non-invasive biomarker of eosinophilic airway inflammation suitable even for young children. FeNO testing is quick, painless, and requires only a few seconds of breathing making it practical in the pediatric clinic setting. Modern FeNO analyzers (such as the handheld electrochemical devices) provide immediate results and include child-friendly interfaces to assist with correct technique. FeNO values can help in decision making and monitoring of asthma control without any invasive procedure . As per American Thoracic Society and European Research Society guidelines, FeNO values with cut offs values > 35ppb has been found to be associated with exacerbations. In our study, during asthma exacerbation, FeNO value of >20.5 ppb was found to be statistically significant with specificity of 81%, sensitivity of 77%, positive predictive value of 52.6 % and negative predictive value of 92.6% with p value of <0.0001. Similarly for Asthma control, FeNO value <14.5 ppb was found to be statistically significant with specificity of 87%, sensitivity of 55%, positive predictive value of 44.9% and negative predictive value of 71% with p value of exacerbation could be because of different microbiota of respiratory system in Indian children, compared to Caucasians being different race with different genetic makeup. ¿p#1 Conclusions: In our study, FeNO >20.5 ppb and AEC 505/µl predicted asthma exacerbations, while FeNO <14.5 ppb and AEC 413/µl predicted asthma control, both with good sensitivity, specificity, and high negative predictive value. In our study there existed a strong, positive correlation between FeNO and AEC in both bronchial asthma and allergic rhinitis patients. ¿p#1 Strength of the study: Our study identified correlation between FeNO levels and Absolute Eosinophil Count in children having Bronchial Asthma and Allergic Rhinitis. This study is probably the first prospective cohort study in Indian children with reasonable sample size, where correlation of biomarkers was studied in children with both diseases. It also gave a FeNO cut off values for asthma exacerbations and control in such patients where currently no standard Indian cut off values were available. ¿p#1 Limitations of the study: This study included children only from urban area of India which may not be representative of entire paediatric population of the country. Hence, further studies are needed with relatively larger sample size representing children from both urban and rural areas to define standard cut off values of asthma exacerbation and control of these biomarkers. There is a big knowledge gap regarding FeNO values during exacerbation and control in Indian Paediatric population because of very limited Indian studies. ¿p#1 Conflict of interest: All authors have none to disclose. ¿p#1 REFERENCES 1. 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Authors Affiliations Harshita Chaudhary View all articles by this author Bal Mukund View all articles by this author Vivek Bhat View all articles by this author Gaurav Mahajan View all articles by this author Metrics & Citations Metrics Article Usage 160 views 67 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Harshita Chaudhary, Bal Mukund, Vivek Bhat, et al. A study of the correlation of Fraction of exhaled Nitric Oxide (FeNO) with Absolute Blood Eosinophil Count (AEC) in Indian children to establish its utility in prediction of control and exacerbation of Bronchial Asthma. Authorea . 17 November 2025. DOI: https://doi.org/10.22541/au.176339531.12414468/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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