Obstructive sleep apnoea (OSA) in octroi employees of Mumbai: Evaluation of waist circumference, diabetes mellitus, metabolic syndrome as risk factors

Obstructive sleep apnea (OSA), a complex disease is a growing health concern globally. Various global epidemiological studies have demonstrated prevalence of obstructive sleep apnea to vary from 0.3% to 5.1%. Clinical scores (CS) are useful to estimate individuals at risk for OSA and predict prevalence of OSA in community based studies. Waist circumference, diabetes mellitus and metabolic syndrome are emerging as important risk factors for OSA. During a preventive health check Octroi employees were found to have sedentary habits and were hence assessed for OSA and its risk factors.

The aims of the study were i) study the overall health status ii) estimate individuals at risk for OSA using the CS and iii) study waist circumference, diabetes mellitus and metabolic syndrome as a risk factor for OSA.

262 Octroi employees, who received preventive health check up at the tertiary care hospital in Mumbai, were invited to participate in the study. A questionnaire was used to assess their demographic characteristics, diet, life styles, and medical history. Body mass index (BMI) was calculated as (weight in kg)/(height in meter)². Waist circumference measurements were made directly above the iliac crest with minimal respiration. Laboratory investigations included complete haemogram, blood sugar estimation, and lipid profile and thyroid function tests. CS included the following parameters 1) loud, habitual snoring 2) interrupted breathing, both reported to the patient by spouse or family members 3) excessive day time sleepiness as evidenced by napping in company or while driving, and/or difficulty in staying awake in quiet surroundings 4) obesity, defined as BMI ≥25kg/m² 5) essential hypertension, identified by the use of hypotensive medications or a BP ≥ 140/90 mm of Hg on more than two separate occasions. Each feature was assigned a score of 1 with a possible maximum score of 5. A score of more than 3 was used to predict individuals at risk for presence of OSA. Metabolic syndrome was diagnosed if 3 out of 5 following variables were present 1) hypertension (BP ≥130/≥85mm of Hg), 2) insulin resistance or glucose intolerance BS&ge;110 mg%), 3) Low HDL cholesterol <40mg%(men), <50mg%(women), 4) elevated triglycerides (<150mg%), 5) abdominal obesity - waist circumference <35inches. Statistical analysis was employed to estimate the association of significant CS with waist circumference, diabetes mellitus and metabolic syndrome.

CS>3 indicating at risk for OSA was present in 12(4.58%) employees. Ten(83.33%) patients with CS>3, had waist circumference ≥35 inches. The association of waist circumference was superior to body mass index (table 1). Metabolic syndrome (p 0.0000353), waist circumference (p 0.0015) but not diabetes mellitus (p 0.6374) showed statistically significant correlation with CS.(table 2)

The risk for OSA using CS was thus 4.58% in the study population. Waist circumference and metabolic syndrome were independent risk factors for OSA.