South Asian Modified NCEP Criteria for Metabolic Syndrome
- Although National Cholesterol Education Program (NCEP) does not provide ethnic-specific cutoff points for waist circumference (WC), the 2005 American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement on MS endorses the lower WC for all Asian Americans (<90 cm for men and <80 cm for women).1
- In 2007, Enas and Mohan have proposed for the first time, the South Asian Modified (SAM)-NCEP Criteria which follows the NCEP criteria for metabolic syndrome (MS) except for the inclusion of South Asian-specific WC cutoff points for abdominal obesity as recommended by the International Diabetic Federation (IDF).2, 3,4 Thus, unlike the IDF criteria, abdominal obesity is considered optional, not essential in SAM-NCEP criteria Table 011.2
- Lee and associates5 studied the prevalence of MS in the presence and absence of abdominal obesity in a multiethnic Asian population in Singapore. From the population-based cohort study (baseline 1992-1995), 4,334 healthy individuals were grouped by the presence or absence of MS and abdominal obesity and followed up for an average of 9.6 years. The prevalence of MS was 18% by IDF criteria but increased to 26% by the SAM-NCEP criteria. This means that 8% of the participants had 3 or more MS components in the absence of abdominal obesity.
- Thus, making abdominal obesity as an essential rather than an optional component to diagnose MS would fail to identify a fairly large proportion of individuals with MS (44%). Specifically, prevalence of MS among Asian Indians would increase by 50%. With application of the SAM-NCEP criteria, Asian Indians had higher rates of MS (38%) than Chinese (24%) and Malays (30%).4,5
- The results of this pioneering study also showed that having MS either with or without abdominal obesity conferred similar CAD risk. There were 135 first-time CAD events during nearly 10 years of follow up. Cox’s proportional hazards model was used to obtain adjusted hazard ratios (HRs) for risk of a first-time CAD event.
- Compared with individuals without MS, the risk of first CAD event was nearly identical in people with and without abdominal obesity. The risk of CAD was 2.8for those with MS with abdominal obesity and 2.5 for those with MS and no abdominal obesity.4,5
- This study has clearly demonstrated that designating abdominal obesity as an optional rather than essential criterion identifies more individuals at risk of CAD. Conversely, this study suggests that including abdominal obesity as an essential component for the diagnosis of MS as proposed by IDF, fails to identify approximately 50% of those who are at high risk of CAD. A similar 50% increase in MS is noted in other Asian populations when SAM-NCEP criteria are used (19% IDF vs. 29% SAM-NCEP) without any decrease in the odds ratio for CAD.6
Prevalence of MS among Asian Indians using SAM-NCEP criteria
- Among South Asians, the prevalence of MS is higher by 30% to 50% when SAM-NCEP criteria are applied compared with NCEP criteria and 20% higher compared with IDF criteria.
- The prevalence of MS for Asian Indians in Singapore increased from 27% with NCEP criteria to 35% with SAM-NCEP criteria.7
- In CURES, the prevalence of MS increased from 18% with NCEP criteria to 30% with SAM–NCEP criteria, whereas another study from the same city (Chennai) reported MS prevalence of 41% with criteria very similar to those of SAM-NCEP.8
- A recent study from rural Andhra Pradesh, India, involving 4,535 adults aged 30 years and older showed a prevalence of MS by NCEP criteria of 27% in men and 18% in women, which increased to 33% and 24%, respectively, when SAM-NCEP criteria were applied. 9
- In a large, contemporary, multicenter study involving 19,973 subjects in India, the prevalence of MS was 27% with NCEP criteria but increased to 35% with SAM-NCEP criteria.10 In addition, there was wide regional variation in the prevalence of MS from as low as 13% to as high as 47% .10
- This increase in prevalence of MS in South Asians is in sharp contrast to that of the US population. If abdominal obesity were not a prerequisite, the prevalence of MS with IDF criteria would increase only slightly from 39% to 40%.11
- The overall prevalence of abdominal obesity is around 50% among Asian Indians when the IDF WC cutoff point is used, and 10% to 20% when the NCEP WC cutoff point is applied.2 This explains why SAM-NCEP is better suited for South Asians.
- The overall prevalence of MS identified with SAM-NCEP criteria among Asian Indians is 30% to 40%, which is double that of Europeans (prevalence is 15%-20%) and similar to that of Americans (prevalence is 35%-40%).2, 8, 12-14
- The controversy about the definition of MS has been finally resolved and there is now a single global definition with specific lower cutpoints for waist circumference for Asian Indians and other Asians as was originally proposed by Enas and Mohan.15, 16
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