Predictors of obstructive sleep apnea syndrome in bronchial asthma patients: investigating the obesity-inflammation interplay through LEP, IL-6, and NLR.

BACKGROUND

Bronchial asthma (BA) frequently coexists with obstructive sleep apnea syndrome (OSAS). The obesity-inflammation axis may underlie this overlap, but pragmatic predictors and biomarker utility remain incompletely defined.

OBJECTIVE

To identify clinical predictors of OSAS in BA and evaluate the diagnostic performance of leptin (LEP), interleukin-6 (IL-6), and neutrophil-to-lymphocyte ratio (NLR), individually and in combination.

MATERIALS AND

METHODS

In a prospective study, 263 adults with BA were enrolled and classified into OSAS (n=124) and non-OSAS (n=139) groups by polysomnography. The OSAS group was stratified by apnea-hypopnea index (AHI) into mild (n=59), moderate (n=42), and severe (n=23). Clinical variables were compared with univariate tests. Independent predictors were identified using binary logistic regression. Serum LEP and IL-6 (immunoassays) and NLR (hematology) were measured. Biomarker-AHI relationships were assessed by Spearman's correlation. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curves and DeLong's test.

RESULTS

On univariate analysis, OSAS cases were older and more often male, with higher rates of obesity, severe BA, neck circumference >40 cm, rhinitis, and gastroesophageal reflux disease (GERD). Logistic regression confirmed obesity, severe BA, neck circumference >40 cm, rhinitis, and GERD as independent predictors. LEP, IL-6, and NLR were significantly higher in OSAS than non-OSAS and increased progressively across AHI strata. LEP correlated strongly with IL-6, IL-6 with NLR, and LEP with NLR to a lesser extent (all P<0.001). For diagnosing BA-OSAS, AUCs were 0.746 (LEP), 0.771 (IL-6), 0.742 (NLR), and 0.826 for their combination, which outperformed individual markers (DeLong, P<0.05).

CONCLUSION

Obesity, neck circumference >40 cm, severe BA, rhinitis, and GERD independently predict OSAS in BA. LEP, IL-6, and NLR correlate with OSAS severity, and their combined use provides superior diagnostic value for identifying BA-OSAS comorbidity and may aid targeted screening and referral. (≈240 words).