Sleep-related breathing disorders, loud snoring and excessive daytime sleepiness in obese subjects

OBJECTIVE: To investigate the prevalence of sleep breathing disorders, loud snoring and excessive daytime sleepiness in a group of obese subjects, and to identify the predictors of obstructive sleep apnea (OSA) severity in th ese patients. SUBJECTS: A total of 161 consecutive obese patients (body mass index (BMI) greater than or equal to 30.0 kg/m(2)), ranging between 30.0 and 67.3, repr esented by 57 men and 104 women, aged 16-75 y. Forty (15 men and 25 women) age-matched (20-70 y) nonobese (BMI < 27 kg/m(2)) volunteers were also recr uited for the study. MEASUREMENTS: Respiratory function parameters, nocturnal sleep quality (eva luated by a specific questionnaire), nocturnal hypoventilation and OSA (eva luated by night polysomnography) were examined in all subjects. Anthropomet ric parameters (neck circumference, waist circumference, waist-to-hip ratio ) were also investigated. RESULTS: Eighty-three obese patients (51.5% of the obese group) had a respi ratory disturbance index (RDI) greater than or equal to 10, corresponding t o a moderate or severe sleep apnea. in particular, 24.8% (40/161), ie a qua rter of all obese patients, were affected by severe OSA and this alteration was present in 42.1% of obese men (24/57) and in 15.4% (16/104) of obease women. When a stepwise multiple regression analysis was performed, neck cir cumference in men and BMI in women were shown to be the strongest predictor s of sleep apnea. Twenty-nine percent of all obese subjects (40.3% of men a nd 23.1% of women) showed nocturnal hypoventilation; however, it was presen t as a unique breathing alteration in only 5% of the obese population. The percentage of patients having excessive daytime sleepiness was significantl y higher than in nonobese subjects, even when only nonapneic obese patients were considered (P < 0.001). CONCLUSION: This study shows that OSA is present in more than 50% of a popu lation of obese patients with a mean BMI higher than 40.0, this percentage being much higher than that commonly reported in previous studies, particul arly in women. Neck circumference in men and BMI in women seem to be the st rongest predictors of the severity of OSA in obese patients. Nocturnal hypo ventilation seems to be present in more than 29% of a severe obese populati on. Moreover, this study indicates that morbid obesity can be associated wi th excessive daytime sleepiness even in the absence of sleep apnea.