Plasma homocysteine levels and cardiovascular mortality in patients with end-stage renal disease

Hyperhomocysteinemia is considered an independent risk factor for atherosclerosis in patients with normal renal function. Plasma homocysteine (Hcy) is increased in patients with chronic renal failure (CRF) and could be linked to their high cardiovascular (CV) morbidity and mortality. We prospectively studied 77 patients (47 males and 30 females aged 62.85 +/- 1.53 yrs) who had been on maintenance hemodialysis (HD) (4 hr/x3/week) for 65.5 +/- 7.23 months. Patients were followed-up for 44 months. At baseline, blood samples were taken for hemoglobin (Hb), total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, serum calcium, serum phosphates, parathyroid hormone (PTH), Hcy, vitamin B12, serum and erythrocyte folate and methylentetrahydrofolate-reductase (t-MTH-FR) genotype determination. Plasma Hcy levels of patients were divided into four quartiles. The univariate analysis demonstrated a significant relationship between Hcy and diastolic blood pressure (BP) (r=0.45; p=0.003), and both plasma (r=-0.30; p=0.03) and erythrocyte (r=-0.48; p=0.01) folate levels and CV score (r=0.39; p=0.007). Kaplan-Meier analysis showed that the mortality rate due to CV events was statistically significantly higher in the 4th Hcy quartile (68%; 12 patients) vs. the 3rd quartile (12%; two patients), the 2nd quartile (28%; four patients) and the 1st quartile (14%; two patients) (log-rank test p=0.02). Cox's regression analysis for CV survival showed that Hcy was a positive CV mortality predictor (beta=0.02; hazard ratio=1.031; 95% confidence interval (95% CI): 1.013-1.050; p=0.001), while LDL cholesterol and albumin related negatively to CV mortality (LDL cholesterol: beta=-0.02; hazard ratio=0.095; 95% CI: 0.0957-0.0997; p=0.035; albumin: beta=-2.35; hazard ratio=0.097; 95% CI: 0.011-0.847; p=0.026). Our results show that Hcy is a strong independent mortality predictor in HD patients with a 3% increase in mortality for each 1 micromol/L increase in plasma Hcy concentration. This agrees with previous findings confirming the role of Hcy in predicting CV risk factors in uremic patients.