Smoking and Obstructive Sleep Apnea: Is There An Association between These Cardiometabolic Risk Factors?—Gender Analysis

Background and Objectives: Studies have tried to establish a relationship between Obstructive Sleep Apnea syndrome (OSA) and smoking but data still remain controversial. We aimed: 1. To evaluate the relationship between smoking and OSA; 2. To explore potential differences according to gender, and 3. To analyze the prevalence of cardiovascular disease (CVD) co-morbidities according to gender and smoking status. Materials and Methods: This retrospective study included 3791 (70.6% males) adult patients who visited a Sleep Clinic. All participants underwent nocturnal polysomnography. Daytime somnolence and insomnia were assessed by using the Epworth Sleepiness Scale (ESS) and the Athens Insomnia Scale (AIS). Ever-smokers completed the Fagerstrom Test for Nicotine Dependence (FTND). Results: OSA was confirmed in 72.1% of participants with 62.2% suffering from moderate-to-severe disease. The number of cigarettes/day, Pack/Years, and FTND were significantly higher in patients with more severe OSA. The prevalence of current smokers was higher in those without OSA or with mild disease, whereas the prevalence of former smokers was higher in moderate and severe OSA. In univariate analysis, current smokers were found to be 1.2 times more likely to have OSA compared with never and former smokers combined and former smokers 1.49 times more likely compared with never smokers. In the multiple regression analysis, after adjusting for BMI, gender, age and number of alcoholic drinks per week, smoking was not found to be significantly associated with OSA. In gender stratified multivariate analyses, no significant associations were observed. CVD co-morbidities were more frequent in more severe OSA. Hypertension, coronary disease and diabetes were more prevalent in former smokers with AHI ≥ 15, compared with current smokers, especially in men. Conclusions: Even if an independent effect of smoking on OSA was not found, the number of cigarettes/day, Pack/Years, and FTND were higher in patients with more severe OSA with more prevalent CVD co-morbidities.