A Study to Evaluate the Effect of Body Mass Index on the Prevalence of Sleep-Disordered Breathing in Adult Patients with Metabolic Syndrome.

BACKGROUND: Obesity is a predisposing factor for obstructive sleep apnoea (OSA). Conversely, OSA increases the risk of developing hypertension and diabetes mellitus. Whether the presence of metabolic syndrome increases the risk of sleep-disordered breathing (SDB) independent of obesity remains unclear.

METHODS: Consecutive 25 non-obese and 25 obese adult patients with metabolic syndrome and Epworth Sleepiness Scale (ESS) score 10 underwent full night attended polysomnography. Baseline clinical and demographic parameters were recorded for all the patients. Obesity was defined as body mass index (BMI) 25kg/m2. Occurrence of SDB (central sleep apnoea and/or OSA), sleep efficiency, and time spent in each sleep stage were noted in both the study groups.

RESULTS: The study subjects were predominantly nen (n=41, 82%) with a mean age of 47.1 years. A total of 38 (76%) subjects were diagnosed to have OSA. There was no difference in the prevalence of OSA between the study groups (non-obese versus obese, 20 [80%] versus 18 [72%]; p=0.508). Patients in both the groups had low median sleep efficiency (non-obese versus obese, 47% versus 48.7%; p=0.764), and an equal number of awakenings per hour of sleep (non-obese versus obese, median interquartile range [IQR], 21 [7.5-26.5] versus 18 [13-22.5]; p=0.763). None of the patients in either group had central sleep apnoea.

CONCLUSION: Obstructive sleep apnoea is highly prevalent in patients with metabolic syndrome and excessive daytime sleepiness (ESS 10), and the prevalence of OSA in this population is independent of BMI.