Hematocrit, independent of chronic kidney disease, predicts adverse cardiovascular outcomes in chinese patients with type 2 diabetes

OBJECTIVE: Anemia and chronic kidney disease (CKD) are risk factors for cardiovascular diseases in diabetes. We examined the association between hematocrit, stratified by the presence of CKD, and cardiovascular events in a cohort of Chinese subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 3,983 patients who underwent assessment for diabetes complications were recruited. Subjects were categorized into five groups. Group I included subjects with hematocrit below the normal sex-specific range. The cutoff points for groups II-V were selected to represent the distribution of the hematocrit for each sex. CKD was defined by the estimated glomerular filtration rate <60 ml/min per 1.73 m(2). Cardiovascular events were defined as cardiovascular mortality and morbidity, including new onset of myocardial infarction, acute coronary syndrome, revascularization, heart failure, and stroke requiring hospitalization. RESULTS: A total of 294 subjects (7.4%) developed cardiovascular events during the median of 36.4 months. The rate of cardiovascular events was highest in subjects with low hematocrit (group I, 18.6%) compared with group V (3.4%, P < 0.001). The multivariate-adjusted hazard ratio for cardiovascular events diminished with increasing hematocrit (group I, 1.0; group II, 0.73 [95% CI 0.51-1.04]; group III, 0.57 [0.39-0.83]; group IV, 0.61 [0.39-0.95]; and group V, 0.36 [0.17-0.79]). After stratifying by the presence of CKD, the previously observed reduction in the risk of developing cardiovascular events with increasing hematocrit was abolished in the cohort with CKD but persisted in the non-CKD cohort. CONCLUSIONS: In Chinese subjects with type 2 diabetes, low levels of hematocrit and the presence of CKD are associated with increased risk of developing adverse cardiovascular events.