Increased Stroke Risk in Metabolically Abnormal Normal Weight: a 10-Year Follow-up of 102,037 Participants in China

The purpose of this study was to investigate the risks of stroke in subjects with metabolically abnormal normal weight (MANW) in China. We recruited 102,037 participants from the Zhejiang Metabolic Syndrome Cohort and the Kailuan cohort. The mean years of follow-up were 9.9 years. General obesity was defined by body mass index (BMI) ≥ 28, overweight by BMI < 28 and ≥ 24, and normal weight by BMI < 24 and ≥ 18.5. Metabolic abnormality was defined as two or more abnormal components (elevated triglycerides, low high-density lipoprotein cholesterol, elevated systolic blood pressure or diastolic blood pressure, or use of antihypertensive drug therapy, elevated fasting plasma glucose, or antidiabetic treatment). A multiple Cox regression model was used to calculate hazard ratio (HR) and its 95% confidence interval (CI), adjusted by potential confounding factors. Overall HR of the risks in two cohorts was calculated by a meta-analysis. Compared with the subjects who were metabolically normal with normal weight (MNNW), the pooled HR for stroke in MANW subjects was 1.82 (95% CI, 1.59-2.07). The risks of stroke in MANW subjects were significantly lower than that in subjects with metabolically abnormal obesity (MAO), but higher than that in those with metabolically normal obesity (MNO) (P < 0.05). These associations remained in the subtypes of cerebral infarction and cerebral hemorrhage. In normal-weight subjects, the HR for stroke was significantly positively correlated with the number of abnormal metabolic components (P_trend < 0.001). In brief, metabolic abnormality increased the risk of stroke irrespective of obesity status. MANW individuals showed a greater risk of stroke, and this risk was positively correlated with the number of abnormal metabolic components.