Serum interleukin-17 as a biomarker in paediatric bronchial asthma: A case control study

Introduction: Bronchial asthma (BA) is a chronic childhood disease causing significant morbidity and mortality. A novel and suitable biomarker is needed for early diagnosis of BA.  Objectives: To establish the association of serum interleukin-17 (IL-17) levels in children with BA and to determine the diagnostic performance of IL-17 in predicting severity of BA.  Method: This was a case control study conducted at the Institute of Child Health and Research Centre, Government Rajaji Hospital & Madurai Medical College, Madurai, India from August 2020 to July 2021. Cases were selected according to the Global Initiative for Asthma (GINA) guidelines and controls were healthy siblings or age and sex matched controls The associations of IL-17 with BA were statistically analysed using Epi info v7 and SPSS 20. Analysis was done using one way ANOVA and t-test. ROC curve was used to find the diagnostic cut-off point. p-value <0.05 was considered statistically significant.  Results: Mean age of the participants was 8.74±2.21 years; 55.8% were males. Mean IL-17 level was significantly higher among cases (2.5±2.7) as compared to controls (1.31±0.96) (p=0.0043). There was a significant increase in mean IL-17 levels with increase in severity (p=0.00). The area under curve for IL 17 levels in diagnosing severe persistent asthma was 0.870 (95% CI=0.708-1.000). The best diagnostic cut-off point was 3.26pg/ml with a sensitivity of 90% and a specificity of 90%. The best diagnostic cut-off point of IL 17 was 1.12pg/ml in predicting asthma with a sensitivity of 60% and a specificity of 50%.  Conclusions: IL 17 level can used as a biomarker for identifying patients with severe persistent asthma.