Impact On Myocardial Infarction And Stroke By Metabolic Syndrome Using Different Definitions

BACKGROUD AND OBJECTIVE:Metabolic syndrome (MS) is an important risk factor for cardiovascular disease (CVD) in the general population, and it has become one of the major public health challenges worldwide. We analyzed data from a cohort study to estimate the impact on myocardial infarction (MI) and stroke by MS using the definitions proposed by the International Diabetes Federation (IDF) and the American Heart Association and the National Heart, Lung, and Blood Institute (revised ATPâ…¢), and explore a MS definition adapt to Chinese population.DESIGN AND METHODS:Study CohortBaseline surveys of two study cohorts were conducted in China in 1998 and 2000, separately. A total of 25,981 participants at the baseline were followed up in 2007-2008, with 20,544 participants completing follow-up survey for an average of 7.9 years.Baseline ExaminationAll baseline data were obtained using a standard questionnaire by trained research staff. Demographic data and other risk factors were collected according to the same protocol. Blood sample was drew for measuring serum total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), and fasting blood glucose (FBG).Follow-Up ProceduresThe follow-up investigation included tracking study participants or their proxies to ascertain disease status and vital information. An end point assessment committee reviewed all hospital records and death certificates and determined the final diagnosis of event or the underlying cause of death.Statistical MethodsStudy participants were grouped into 3 categories by IDF and revise ATPâ…¢definition of MS.1) no-MS:participants who met neither the IDF nor the revised ATP â…¢definition of MS.2) O-rATP MS:participants who met the revised ATPâ…¢only, but not the IDF definition of MS.3) IDF MS:participants who met both of IDF and revised ATPâ…¢definitions of MS. In addition, rATP MS was composed of O-rATP MS and IDF MS. Incidence densities and cumulative incidences of MI and stroke were calculated in each category. Cox proportional hazards regression models were used to adjust for baseline variables, and compute hazard ratios (HR) estimating the relative risk (RR) of MI and stroke associated with MS categories. The population attributable risk percent (PARP) was used to estimate the proportion of MI and stroke explained by MS categories.RESULTS:After adjusted for age, the incidence and mortality of MI in O-rATP MS group (231.48 and 134.23 per 100,000 person-years) were much higher than those in IDF MS group (156.06 and 58.69 per 100,000 person-years). However, the age-adjusted incidence and mortality of stroke in O-rATP MS group (451.27 and 159.68 per 100,000 person-years) were similar with those in IDF MS group (446.26 and 148.45 per 100,000 person-years).Compared with IDF MS, the multivariate adjusted HRs of MI incidence and mortality for O-rATP MS were higher (2.83 vs.2.25; 2.84 vs.1.57). The multivariate adjusted HRs of stroke incidence and mortality for O-rATP MS were 1.86 and 1.50, which were of little difference with that for IDF MS (2.04 and 1.60).There were 17.26% of MI incidence,8.73% of MI mortality,14.78% of stroke incidence and 9.11% of stroke mortality in population attributable to IDF MS, respectively. While,24.57% of MI incidence,17.83% of MI mortality,18.48% of stroke incidence and 11.56% of stroke mortality in population could be explained by rATP MS, respectively.After the revised ATPâ…¢definition of MS was modified to fit the HDL-C level in China (the cutoff for HDL-C was less than 1.04 mmol/L for both male and female), 21.57% of MI incidence,14.37% of MI mortality,16.83% of stroke incidence and 12.00% of stroke mortality were attributed to the modified MS in population, respectively.CONCLUSIONS:The impact of O-rATP MS on incidence and mortality of MI is much stronger than the impact of IDF MS, and the impact of O-rATP MS on incidence and mortality of stroke is similar to that of IDF MS. It should be rational that using the revised ATPâ…¢definition of MS instead of the IDF definition in prediction of MI and stroke in Chinese population. After the revised ATPâ…¢definition of MS was modified, MS remained to be associated with the incidence and mortality of MI and stroke in China.