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.