Exposure-weighted scoring for metabolic syndrome and the risk of myocardial infarction and stroke: a nationwide population-based study.

Background: Metabolic syndrome (MetS) status changes over time, but few studies have investigated the relationship between the extent or duration of exposure to MetS and the risk of cardiovascular disease (CVD). We investigated the cumulative effects of MetS and its components on the risk of myocardial infarction (MI) and stroke.
Methods: From the Korean National Health Insurance database, 2,644,851 people who received annual health examinations from 2010 to 2013 were recruited. Exposure-weighted scores for MetS during this 4-year period were calculated in two ways: cumulative number of MetS diagnoses (MetS exposure score, range: 0-4) and the composite of its five components (MetS component exposure score, range: 0-20). The multivariable Cox proportional-hazards model was used to assess CVD risk according to the exposure-weighted scores for MetS.
Results: MetS was identified at least once in 37.6% and persistent MetS in 8.2% of subjects. During the follow-up (median, 4.4 years), 10,522 cases of MI (0.4%) and 10,524 cases of stoke (0.4%) occurred. The risk of MI and stroke increased gradually with increasing exposure scores of MetS and its components (each P for trend < 0.0001). The hazard ratio [(HR) (95% CI)] of MI and stroke were 5.27 (4.20-6.62) and 3.90 (3.09-4.93), respectively, in those with a score of 20 compared with those with a MetS component exposure score of 0. People fulfilling only two MetS components out of 20 already had 22% increased risk of MI, and those with three MetS components had 24% increased risk of stroke. These associations were consistent in the subgroup and sensitivity analyses.
Conclusions: A dose-response relationship between the cumulative exposure to metabolic disturbances and incident MI or stroke was evident. Even minimal exposure to MetS components was sufficient to increase the risk of CVD significantly, highlighting the importance of intensive risk management for the prevention of CVD.