Risk of ischemic stroke in metabolically healthy obesity: a nationwide population-based study

Abstract

Background Whether metabolically healthy obese (MHO) individuals are at increased risk of ischemic stroke is not well known. We investigated the association of the MHO phenotype with ischemic stroke. Methods A total of 354,083 adults (age 45.8 ± 14.2 years) from the Korean National Health Insurance Service–National Sample Cohort enrolled in 2004-2008 were followed-up for incident ischemic stroke until 2013. Obesity was defined as body mass index (BMI) ≥ 25 kg/m2. Subjects meeting none of the metabolic syndrome criteria were classified as metabolically healthy. The cohort was categorized into four groups according to obesity and metabolic status: metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), MHO, and metabolically unhealthy obese (MUO). Results Ischemic stroke was newly diagnosed in 4,884 (1.4%) individuals during a mean follow-up of 7.4 ± 1.5 years. While higher BMI was associated with a significantly increased risk for stroke, the effect of BMI differed according to metabolic health status. In metabolically healthy individuals, obesity did not increase the risk for ischemic stroke, regardless of the severity of obesity. Meanwhile, in metabolically unhealthy individuals, being obese was significantly associated with increased risk of stroke. Stroke incidence rates for the MHNO, MUNO, MHO, and MUO groups were 0.56, 2.61, 0.61, and 2.76 per 1,000 person-years, respectively. Risk for stroke increased significantly in metabolically unhealthy groups, but it was not increased in MHO compared to the MHNO group on multivariate analysis. Conclusions MHO individuals were not at increased risk for ischemic stroke. However, obesity increased risk for ischemic stroke in persons with metabolic risk factors

therefore, maintaining normal weight may be more important for this population. Also, metabolic unhealthiness showed greater association than obesity with stroke.