OBSTRUCTIVE SLEEP APNOEA AND ROLE OF INTERLEUKIN-6 AS A CIRCULATORY BIOMARKER: A CROSS-SECTION STUDY

Abstract

Background: Despite reported link between OSA and systemic inflammation, results are indecisive so far for different inflammatory markers to evaluate the casual relation with OSA and its co-morbidities. Objective of this study was to assess the relationship of inflammatory cytokine Interleukin-6 with obstructive sleep apnoea (OSA) and its severity among Pakistani population. Methodology: A total of 180 subjects (55 without apnoea, 33 mild, 34 moderate, and 58 with severe apnoea) were analysed in this cross-sectional study, between Dec 2018 and Jan 2020 in Dow University Hospital, Karachi. Apnoea was confirmed and subjects were grouped on the basis of Apnoea Hypopnea Index (AHI) by overnight Polysomnography. Plasma IL-6 was analysed using enzyme-linked immunosorbent assay (ELISA). One-way ANOVA was used for comparison. Potential effect of age and BMI was controlled using ANCOVA and effect size was reported as partial eta squared. Results: Mean IL-6 levels were associated with severity of apnoea with 4.72±1.50 pg/ml, 21.08±6.83 pg/ml, 25.41±7.97 pg/ml and 26.96±7.39 pg/ml in no OSA, mild, moderate and severe OSA respectively, with statistically significant difference between all groups except between moderate and severe OSA. After controlling the potential effect of age and BMI still yielded a significant positive association between severity of OSA and IL-6 levels (effect size (partial ?²) of 59% (p<0.001)). Conclusion: Higher Interleukin-6 levels were observed in OSA and associated with its severity. It could provide a feasible method to improve timely diagnosis of OSA and can point toward presence of a more severe clinical phenotype.

Pak J Physiol 2021;17(2):15–9