Body mass index and cardiovascular risk factors and biomarkers in hemodialysis patients

BACKGROUND: Being overweight and obesity are associated with improved survival in hemodialysis (HD) patients, based on mechanisms that are presently uncertain. We compared traditional and uremia-related cardiovascular risk factors in HD patients stratified according to their body mass index (BMI). METHODS: One hundred sixteen HD patients were stratified into 4 groups according to the BMI: underweight (<18.5), normal weight (18.5-24.9), overweight (25.0-29.9) and obese (> or =30). Blood samples were obtained before the HD session to measure serum albumin, high-sensitivity C-reactive protein, fibrinogen, ferritin, total cholesterol, LDL cholesterol, HDL cholesterol, apolipoprotein A-I and apolipoprotein B-100, apolipoprotein B (apoB) to apolipoprotein A (apoA) ratio and Lp(a) lipoprotein. RESULTS: There were 3 underweight (excluded from the analysis), 58 normal weight, 35 overweight and 20 obese patients. Their mean age was 62.1 +/- 14.1 years. There were 68 men and 45 women. Mean dialytic age was 5.32 +/- 3.2 years. The mean BMI of the study population was 25.2 +/- 4.1. The prevalence of smoking habit was similar in the 3 groups (17.2%, 8.5% and 25%, respectively; p=0.28). The prevalence of hypertension was higher in overweight (77.1%) and obese (65%) patients than in leaner counterparts (53.4%), although the difference was not significant. Conversely, diabetes prevalence was significantly higher in overweight and obese patients (22.8% and 30%, respectively) than in normal weight patients (6.9%; p=0.02). The serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, Lp(a) lipoprotein, apolipoprotein A-I, apolipoprotein B-100, and apoA/apoB ratio were similar in the 3 BMI groups. Triglycerides levels were significantly higher in obese (221.2 +/- 132.7 mg/dL) and overweight (230.5 +/- 119.3 mg/dL) patients than in those of normal weight (154.6 +/- 78.8 mg/dL; p=0.02). Most of the uremia-related cardiovascular risk factors (anemia, hyperparathyroidism, chronic inflammation) were comparable among BMI categories as well as the levels of C-reactive protein, fibrinogen and ferritin. CONCLUSION: The present study suggests that almost all traditional and uremia-related cardiovascular risk factors do not differ significantly among different categories of BMI in hemodialysis patients.