Comparison of definitions of the metabolic syndrome in adult Asian Indians.

OBJECTIVE The optimum definition of the metabolic syndrome (MS) is not known. We compared international definitions of MS [recently proposed modified definition of National Cholesterol Education Programme, Adult Treatment Panel III (NCEP, ATP III) and International Diabetes Federation (IDF)] with two proposed candidate definitions in adult Asian Indians. DESIGN Data from three previous cross-sectional studies carried out in North India were analyzed. SUBJECTS The study included 2050 adult (mean age: 40 +/- 18 years) Asian Indian subjects residing two metropolitan cities. MEASUREMENTS Candidate definitions of MS were proposed by modifying the NCEP, ATP III and IDF definitions by including the following modified variables into two combinations (MS-ATP1 and MS-IDF1); waist circumference cut-off points as >90 cm in males and >80 cm in females, body mass index (BMI) cut-off point as >23 kg/m2, impaired fasting glucose (IFG) cut-off point >100 mg/dl and waist circumference as an obligatory criterion. RESULTS Maximum overall and gender-specific prevalence of the MS (49.2% overall; 41.4% in males; 55.3% in females) was observed using the definition which included modified cut-off points of WC (non-obligatory), BMI, and IFG (>100 mg/dl) in addition to other defining parameters. Compared to other definitions this proposed candidate definition maximally detected presence of MS in subjects with IFG and T2DM [Percentage prevalence: 78.1% (73.0-82.7) and 91.1% (84.2-95.6)]. Even in subjects without abdominal obesity, a high prevalence of other abnormal defining parameters of the metabolic syndrome; hypertension (> or = 130 or > or = 85 mmHg), 35.7%; BMI >23 kg/m2, 15.3%; hypertriglyceridemia (>150 mg/dl), 20.2% and low levels of HDL-C (<40 in males; <50 mg/dl in females), 55% were seen. Further, 10.5% of subjects who did not have abdominal obesity had presence of at least 3 risk variables of the metabolic syndrome. These data indicate that by making abdominal obesity a mandatory criterion would lead to missing of some cases of the metabolic syndrome. CONCLUSION By including BMI and making waist circumference as a non-obligatory criterion, more cases of the metabolic syndrome is detected. For Asian Indians, making waist circumference as mandatory variable in the definition of the metabolic syndrome would lead to non-inclusion of nearly 11% cases who would otherwise be diagnosed as metabolic syndrome according to modified NCEP, ATP III definition.