Trend in the prevalence of the metabolic syndrome and its impact on cardiovascular disease incidence: the San Antonio Heart Study.

OBJECTIVE: With the current obesity epidemic, one would expect a prevalence increase in the metabolic syndrome. Therefore, in the San Antonio Heart Study, a population-based study with worsening obesity, we examined the metabolic syndrome and its effect on incident cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS: We enrolled 5,158 subjects in two cohorts: 1979-1982 and 1984-1988. We reexamined 3,682 (71.4%) subjects in 1987-1990 (cohort 1) and 1991-1996 (cohort 2) and assessed a 7.5-year incidence of CVD in 4,635 (90.0%) participants. We used the metabolic syndrome definition of the National Cholesterol Education Program-Adult Treatment Panel III.
RESULTS: At baseline, the metabolic syndrome was less prevalent in cohort 1 than in cohort 2: in men, 20.4 vs. 29.3% (P < 0.001); in women, 16.3 vs. 26.3% (P < 0.001). The prevalence increased in men and women of both Mexican-American and non-Hispanic white ethnic groups between 1979-1982 and 1991-1996 (P for trend <0.001 for each of the groups). There was an excess of incident CVD in cohort 2 relative to cohort 1 (odds ratio 1.37 [95% CI 1.02-1.84]) after adjustment for age, sex, ethnic origin, socioeconomic status, history of CVD, diabetes, total cholesterol, smoking, and family history of heart attack. Further adjustment for the metabolic syndrome reduced this difference (1.26 [0.93-1.71]) because the metabolic syndrome predicted incident CVD (1.58 [1.14-2.18]).
CONCLUSIONS: In San Antonio, Texas, an increase in the prevalence of the metabolic syndrome between 1979-1982 and 1984-1988 contributes to explain a higher CVD incidence.