The MetSyn was defined by WHO criteria in 6 studies (36,41,47- 48,51,61), NCEP criteria in 12 studies (39- 40,42- 43,47,53- 55,57,59,61- 62), modified WHO criteria in 4 studies (28,39,54,58), and modified NCEP criteria in 10 studies (27,39,44- 46,49- 50,56,60). Most modifications substituted body mass index for waist circumference or waist-to-hip ratio, or omitted the proteinuria component of the WHO criteria. A few studies added additional components, such as C-reactive protein (45) and uric acid (38,52). Factor analysis was used in 5 studies (31,33- 34,39,52) to create a novel variable, or factor, comprised of statistical loadings of highly inter-correlated participant characteristics (analogous to clustered risk factors in the MetSyn), which was then used as a parameter in regression models for incident cardiovascular disease. The factors in these studies were nearly identical to the components in WHO and NCEP definitions of MetSyn. Some studies developed MetSyn criteria using threshold values for its components based on the extreme tertiles to quintiles of their distribution (30,32,35,37). One study that presumably had a predominantly Japanese population used a lower threshold for systemic obesity (a body mass index >25 kg/m2) in its modified WHO criteria (58), but no other studies modified their criteria to account for ethnic differences.