Incidence and risk factors for metabolic syndrome among urban, adult Sri Lankans: a prospective, 7-year community cohort, follow-up study

BACKGROUND: The metabolic syndrome (MetS) is a clustering of abdominal obesity, diabetes and prediabetes, high cholesterol and high blood pressure, that confers an increased risk of cardiovascular disease. There is limited data on incidence of MetS from South Asia. This study investigated incidence and risk factors for new onset MetS in an urban adult Sri Lankan population. METHODS: Subjects (selected by age-stratified random sampling from the Ragama Medical Officer of Health area) were screened initially in 2007 (35–64 years) and re-evaluated in 2014 (42–71 years). On both occasions they were assessed by structured interview, anthropometric measurements, liver ultrasound, and biochemical/serological tests. MetS was diagnosed on International Diabetes Federation (IDF-2006) criteria. Total body fat (TBF) and visceral fat percentage (VFP) were measured in 2014, using body impedance method. Incidence and factors at baseline, associated with new onset MetS, were investigated among those who presented for re-evaluation. RESULTS: 2985 (99.1%) [1636 (54.8%) women (54.8%); median age (IQR) 53 (47–59) years] from the initial cohort in 2007 had complete data. 2148 (71.9%) [1237 (57.6%) women; median age (IQR) 60 (54–66) years] attended follow-up. 949 of them [701 (73.9%) women; median age (IQR) 60 (54–65) years] had MetS (prevalence 47.2%, 95% CI 45.0–49.4%). Of 1246 who did not have MetS in 2007, 265 [178 (67.1%) women, median age (IQR) 57 (51–64) years] had developed MetS after 7 years (annual incidence 3.5% (95% CI 2.4–4.5%). Females (OR = 4.9, 95% CI 3.4–7.4), BMI > 23 kg/m(2) in 2007 (OR = 1.6 per unit increase, 95% CI 1.5–1.7), weight gain (by 2–5% OR = 2.0, 95% CI 1.1–3.5; by > 5% OR = 2.2, 95% CI 1.4–3.4), and increase in waist circumference (by 2–5% OR = 7.0, 95% CI 4.0–12.2; by > 5% OR = 13.4, 95% CI 8.3–22.4) from baseline and presence of non-alcoholic fatty liver disease (NAFLD) in 2007 (OR = 1.70, 95% CI 1.04–2.76) were associated new onset MetS. Those with MetS had abnormal VFP and TBF in 2014 [P < 0.001]. CONCLUSION: In this study, annual incidence of MetS was 3.5%. Female gender, BMI > 23 kg/m(2) and NAFLD in 2007 and increase in weight and waist circumference from baseline were significantly associated with new onset MetS. Obesity was the best predictor of future MetS.