Age variation and sexual dimorphism in the sixteen diagnostic clusters of risk factors for the metabolic syndrome
OBJECTIVE: To document age- and sex-related differences in the 16 phenotypes of risk factors for the metabolic syndrome (MS) among adults in the Fels Longitudinal Study (FLS). METHODS: Data on risk factors for the MS were analyzed in 471 white men and 503 white women in the FLS. We used the Cochran-Armitage test to compare age- and sex-related differences in the prevalence of the 16 diagnostic clusters of positive risk factors. RESULTS: Of the 974 subjects, 238 were found to meet diagnostic criteria for 15 of a possible 16 phenotypes of the MS. The prevalence of the MS was four times greater in subjects older than 40 years than in subjects 20-40 years old. Older subjects had more risk factors exceeding criterion values than younger subjects. Among those who met three-to-five criteria for the MS, younger subjects were more likely to have dyslipidemia, less likely to have high blood pressure (HBP), and two times less likely to have impaired fasting plasma glucose (IFG) than subjects 40+ years old. Older men were more likely than older women to have HBP and IFG. . We found that if one of the five risk factors reaches a criterion value, the values for the other four risk factors move closer to their own diagnostic criterion values in apparent synchrony. CONCLUSIONS: Subjects 40+ years old are four times likelier to have the MS than younger subjects, and older men are at higher risk than older women. The mean values for each of the five risk factors get progressively worse as the number of risk factors meeting diagnostic criteria increases. Therefore, when one factor is found to meet its diagnostic criterion, levels of the other four risk factors should be measured. The different phenotypic patterns that comprise the MS should prompt clinicians to target specific risk factors for prevention or treatment. Certain phenotypes were found more commonly in women and certain others more commonly in men. Similarly, certain phenotypes were found more commonly in older than in younger age groups. These age- and sex-specific phenotypes should help clinicians to identify subjects at highest risk for certain risk factors and to initiate specifically tailored preventive and therapeutic interventions. Our observations should also stimulate clinical investigators and epidemiologists to ascertain what factors determine the sex and age specificity of certain phenotypes of the MS.