Obstructive Sleep Apnea in Metabolic Syndrome

The metabolic syndrome (MetS), a cluster of cardiovascular risk factors, is associated with obstructive sleep apnea (OSA). OSA is a major contributor to cardiac, cerebrovascular, and metabolic disorders as well as to premature death.

This cross-sectional study was done for 1 year in 103 patients of MetS diagnosed by the International Diabetes Federation criteria. All patients were subjected to the STOP-Bang questionnaire, and they were classified into low, intermediate, and high risks depending on the score. Patients falling in intermediate-high risk (score 3-8) were taken for overnight polysomnography to confirm the diagnosis of OSA (apnea-hypopnea index [AHI] ≥5) and were considered Group I. Patients with STOP-Bang score ≤2 or score ≥3 with AHI <5 were considered Group II (non-OSA).

Out of 103 MetS patients enrolled in the study, only 70 (68.0%) were diagnosed with OSA, so the prevalence of OSA in MetS patients was 68%. The majority of the OSA cases had moderate-to-severe OSA (68.5%), and only 31.4% had mild OSA. The age of patients enrolled in the study ranged between 29 and 78 years, and the mean age of patients was 54.8 ± 9.4 years. Out of 103 MetS enrolled in the study, 59 (57.3%) were male and the rest were female, so the prevalence of severe OSA was higher in males than in females. The prevalence increases with an increase in age groups. Weight, body mass index (BMI), circumference, and waist circumference (WC) of cases of OSA were found to be significantly higher as compared to that of non-OSA. An incremental trend of increase in weight, BMI, neck circumference, and WC was observed with the increase in the severity of OSA. Patients of OSA as compared to non-OSA had significantly increased WC, blood pressure (BP), fasting, postprandial, random blood sugar, and triglyceride (TG) levels. A trend of increase in WC, BP fasting, postprandial, random blood sugar, and TG levels was associated with an increase in the severity of OSA. Snoring and daytime sleepiness were observed in a significantly higher proportion of OSA cases as compared to non-OSA cases.

This study shows that OSA has a high prevalence in subjects with MetS. A high index of clinical suspicion is required for early diagnosis.