Joint Associations Between Plasma 25-Hydroxyvitamin D, Glycemic Status and First Stroke in General Hypertensive Adults: Results From the China Stroke Primary Prevention Trial (CSPPT).

Background Associations between vitamin D and stroke remain inconsistent. One major risk factor for stroke is high blood glucose, but the role it plays in this association is not well-studied. Objectives We aimed to evaluate the individual association between plasma 25-hydroxyvitamin D (25(OH)D) and risk of first stroke stratified by fasting blood glucose (FBG), and the joint associations between plasma 25(OH)D, glycemic status and first stroke in hypertensive adults. Methods This study was a nested, case-control design utilizing data from the China Stroke Primary Prevention Trial (CSPPT). This analysis included 591 first stroke cases (of which 475 were ischemic stroke, 114 were hemorrhagic stroke, and 2 were uncertain type) and 591 matched controls. The age range of the study population was 45-75 years. The normal FBG (NFG) group had FBG Results Multivariable adjusted models revealed an inverse association between quartiles of 25(OH) D and risk of first stroke among participants with NFG, but the opposite trend was observed for those with IFG or diabetes. The largest odds ratios (>2) were observed among patients with diabetes, compared to the reference group of NFG and high 25(OH)D. Those with NFG and low 25(OH)D (OR = 1.73, 95%CI = 1.22 to 2.44) or those with IFG and high 25(OH)D (OR = 1.74, 95%CI = 1.14 to 2.67) both had higher risk of total stroke. There was a significant interaction between 25(OH)D and a combined group of IFG and diabetes (P = 0.001). Similar results were observed for ischemic stroke. Conclusions In a hypertensive population, the relation between plasma 25(OH)D and risk of first stroke was significantly modified by fasting blood glucose.Registration-URL: https://www.clinicaltrials.gov. Unique identifier: NCT00794885.