5-methyltetrahydrofolate Survival and Inflammation in ESRD Patients

BACKGROUND Hemodialysis patients show a 20-fold increase in CVD mortality in comparison to the general population. Although hyperhomocysteinemia has been implicated as an important independent risk factor in both the general population2, as well as for ESRD patients, several studies have questioned the benefit of lowering homocysteine in ESRD patients. Paradoxically, two recent studies showed that patients with very low homocysteine plasma levels had worse outcomes including a higher incidence of hospitalization and mortality. This raises the question as to whether elevated homocysteine in uremic patients is consequential rather than causal in the role of cardiovascular complications. Despite this uncertainty, many ESRD and pre-ESRD patients receive treatment to lower homocysteine. Elevated homocysteine is frequently reported for ESRD patients with a prevalence ranging from 85 to 100%. There are two basic strategies that can be used to lower homocysteine. Both attempt to increase levels of biologically active folate which is essential in the remethylation pathway of homocysteine metabolism via its active metabolite 5-methyltetrahydrofolate (5-MTHF), thus lowering homocysteine efflux from tissues into the plasma compartment. The first, and most common approach, is by oral administration of folic acid. Folic acid is not biologically active, however it is more stable than folate, and is often used in tablets and food fortification. The second approach is to supplement 5-MTHF, the natural circulating form of folate. In addition to folate, both vitamin B6 and vitamin B12 are necessary co-factors in homocysteine metabolism. ESRD patients are often resistant to homocysteine lowering by administration of both folic acid and 5-MTHF. Although supplementation with folic acid, B6 and B12 usually decreases homocysteine in patients with vascular disease, it often remains elevated in ESRD patients despite supplementation of folic acid, B6 and B12. Several studies have reported only moderate effects, even with very high doses of folic acid (up to 15 mg/daily). AIM OF THE STUDY The aim of this study is to investigate whether supplementation with 5MTHF vs. folic acid treatment affects patient survival. Homocysteine blood levels and MTHFR genetic polymorphisms will also be evaluated to determine if they can be considered as independent cardiovascular risk factors. STUDY DESIGN Single center, randomised, prospective study. Two groups of stable ESRD patients treated with intravenous 5-MTHF or with 5 mg per day of oral folic acid. Patient selection Period of selection : 4 years Start selection : 1 January 1998 End selection: 30 June 2001 Follow-up: 55 months. STATISTICAL ANALYSIS Statistical analysis will be performed by the Statistical Package for the Social Sciences (SPSS).