Are conventional cardiovascular risk factors predictive of two-year mortality in hemodialysis patients?

Background: In general population hypertension, diabetes mellitus, overweight, hyperlipidemia and smoking are well-established risk factors for cardiovascular disease. However, the effect of these conventional risk factors on cardiovascular disease and mortality of patients on hemodialysis is not well understood. Indeed, some risk factors such as high blood pressure, hyperlipidemia and excess weight have been recently claimed to correlate with improved survival. Objective: This study was undertaken to define the prevalence of these conventional risk factors in 453 hemodialysis patients, predominantly African-Americans, to determine their influence on two-year survival. Result: High cholesterol was found in 30% of the patients, high LDL-cholesterol in 25% and high triglycerides in 16%. Lipoprotein(a) (LP(a)) was elevated in 68% of the patients. 31% of our patients had predialysis mean arterial blood pressure (MAP) over 114, and 25% were obese based on a body mass index (BMI) over 30, 26% were diabetic and 25% were active smokers. Smoking was more common among our male and Caucasian patients. The aggregate score for the risk factors were 2.4 +/- 0.1 per patient, which increased to 3.2 +/- 0.1 in patients with obesity or diabetes, to 3.0 +/- 0.1 with hypertension and to 2.8 +/- 0.1 with active smoking. In multivariate Cox model analysis, prealbumin, body weight and blood pressure showed a positive correlation with two-year survival whereas diabetes mellitus had a negative correlation. Hyperlipidemia did not correlate to patients' two-year mortality. Smoking was associated with higher mortality, but that did not reach statistical significance. Conclusion: Conventional risk factors at least over a two-year period do not readily account for the higher mortality of a group of predominantly African-American patients on hemodialysis. The lack of prediction is speculated to be partly due to the overriding beneficial effects of better nutrition and due to the presence of other yet to be well-defined factors such as hyperhomocysteinemia, oxidative stress, coronary calcification, hitherto unidentified uremic toxins or a combination of these factors.