Supplementary Material for: Free 25-Vitamin D Is Correlated with Cardiovascular Events in Prevalent Hemodialysis Patients but Not with Markers of Renal Mineral Bone Disease

Free vitamin D is the biologically active form of vitamin D. Vitamin D deficiency is associated with cardiovascular disease, the most common cause of mortality in hemodialysis patients. The goal of our current study was to investigate the relation between blood concentrations of free 25-hydroxyvitamin D with cardiovascular events in end-stage chronic kidney disease patients on hemodialysis, because this is unknown so far. We measured free vitamin D levels in 117 stable consecutive prevalent patients in September as a surrogate of vitamin D exposure during the past 6 months, and recorded the number of cardiovascular events during the previous 6 months defined as hospitalization due to heart failure, episodes of acute coronary syndrome, and stroke. Fourteen events occurred during the observation period. In patients without any cardiovascular events the free vitamin D levels were significantly higher as compared to those with cardiovascular events (patients without events: 5.68 [4.37–9.27] pg/mL; patients with events: 4.74 [3.46–5.37] pg/mL, p = 0.015). This finding remained stable after multiple regression analysis considering confounding factors such as age, time on dialysis, preexisting diabetes, hypertension, and coronary heart disease. In conclusion, our study shows that free vitamin D serum concentrations are independently associated with major cardiovascular events in chronic kidney disease patients on dialysis.

游离维生素D（free vitamin D）是具有生物学活性的维生素D形式。维生素D缺乏与心血管疾病相关，而心血管疾病是血液透析（hemodialysis）患者最常见的死亡原因。本研究旨在探讨接受血液透析的终末期慢性肾脏病（end-stage chronic kidney disease）患者体内游离25-羟维生素D的血液浓度与心血管事件之间的关联，目前该关联尚未明确。研究人员于9月对117例病情稳定的连续性现症血液透析患者检测了游离维生素D水平，以此作为过去6个月维生素D暴露情况的替代标志物；同时记录了前6个月内的心血管事件发生例数，心血管事件定义为因心力衰竭、急性冠脉综合征（acute coronary syndrome）发作及脑卒中（stroke）住院的情况。观察期内共发生14例心血管事件。未发生心血管事件的患者，其游离维生素D水平显著高于发生心血管事件的患者（无事件组：5.68 [4.37~9.27] pg/mL；事件组：4.74 [3.46~5.37] pg/mL，p=0.015）。在校正年龄、透析时长、既往糖尿病、高血压及冠心病等混杂因素后开展多元回归分析（multiple regression analysis），上述研究结果仍保持稳定。综上，本研究表明，接受透析治疗的慢性肾脏病患者血清游离维生素D浓度与主要心血管事件呈独立相关。