Associations Between Obstructive Sleep Apnea and Cotinine: A Cross-Sectional Study Based on 2015-2020 NHANES

Objective To investigate the associations between tobacco exposure biomarkers (serum/urinary cotinine) and questionnaire-defined obstructive sleep apnea (OSA) using nationally representative data. Background Tobacco exposure may be associated with higher odds of OSA through airway inflammation and oxidative stress, but population-level evidence linking cotinine, a nicotine metabolite, to OSA remains limited. Methods We used the National Health and Nutrition Examination Survey (NHANES) Sleep Questionnaire to identify participants with OSA.Participants were classified into four groups-nonsmokers, secondhand smoke (SHS) exposed, smokers, and heavy smokers - based on serum cotinine levels. Multivariable logistic regression, subgroup analyses, and sensitivity analyses were conducted to examine associations between cotinine levels and questionnaire-defined OSA. Results We analyzed NHANES data collected from 2015 to March 2020. Among 11,039 participants, 1,700 (15.4%) were identified with OSA. Logistic regression showed a significant positive association between serum cotinine levels and OSA (OR: 1.04, 95% CI: 1.02-1.05, p < .001). Compared with nonsmokers, participants exposed to SHS, smokers, and heavy smokers had 1.28-, 1.37-, and 1.53-fold higher odds of questionnaire-defined OSA, respectively. Urinary cotinine levels were also significantly linked to OSA (OR: 1.04, 95% CI: 1.01-1.08, p = .02). Conclusions Both active smoking and SHS exposure are positively associated with higher odds of questionnaire-defined OSA.