Impact of metabolic disorders on the relation between overweight/obesity and incident myocardial infarction and ischaemic stroke in fertile women: a nationwide cohort study

Aims: Whether overweight is a risk factor for cardiovascular disease in the absence of metabolic disorders remains under debate and is largely unexamined in young women. We evaluated the risk of myocardial infarction and ischaemic stroke in fertile women conditional on time-dependent presence of metabolic disorders. Materials and methods: From nationwide registers we identified all normal weight ( body mass index [BMI] >= 18.5 to <25 kg m(-2)) and overweight (BMI 25 kg m(-2)) Danish women giving birth from 2004 to 2009. Using multivariable Poisson regression models adjusted for age, calendar year and smoking, the risk of the composite outcome of myocardial infarction and ischaemic stroke was assessed with metabolic disorders (i.e. hypertensive conditions, abnormal glucose metabolism and/or dyslipidaemia) included as time-dependent variables. Results: The population comprised 261 489 women with median age of 30.5 years (interquartile range = [27.3, 33.8]). Median follow-up was 5.6 years (interquartile range = [4.0, 6.8]). Compared with normal weight women without metabolic disorders (with an incidence rate [IR] of 17.0 [95% confidence interval {CI} = 14.5-20.0] events per 100 000 person-years), overweight women without metabolic disorders had no significantly increased risk, IR 22.6 (CI = 18.3-27.8), adjusted incidence rate ratio (IRR), 1.26 (CI = 0.97-1.65). For women with metabolic disorders, IR was 30.2 (CI = 18.8-48.6) and adjusted IRR 1.77 (CI = 1.07-2.93) in normal weight, while IR was 87.1 (CI = 67.6-112.2) and IRR 4.24 (CI = 5 3.11-5.79) in overweight. Conclusions: The risk of myocardial infarction and ischaemic stroke was more strongly associated with the presence of metabolic disorders than with overweight per se in fertile women. Targeting prevention of metabolic disorders might be beneficial to reduce cardiovascular disease in overweight/obese young women.