No association between hyperhomocysteinemia and vascular access thrombosis in chronic hemodialysis

PURPOSE. Hyperhomocysteinemia, recognized as a risk factor for cardiovascular diseases, has also been related with controversy to vascular access thrombosis in hemodialysis. Our objective was to determine if such an association could be found in our hemodialysis population. METHODS. The survey was conducted in a cohort of 165 chronic hemodialysis patients. Their vascular access history was considered from hemodialysis initiation until November 1999, including the number of vascular accesses created (either native or synthetic fistulae), focussing on vascular access thrombotic events, and excluding primary vascular access dysfunction. Diabetes, hemoglobin, erythropoietin dose, anticoagulation, and methyltetrahydrofolate reductase (MTHFR) status were considered. Serum total homocysteine (tHcy) measures were sampled for all patients in June 1998 and repeated yearly. Patients had not been supplemented routinely with hydrosoluble vitamins until June 1998, after which all received DiaVite (R&D Laboratories, CA, USA) daily. RESULTS. Median survival of native fistulae was significantly longer (81 months, 95%CI 35-127) than for synthetic fistulae (31 months, 95%CI 27-51). Median vascular access survival was reduced for diabetics vs non diabetics (28 vs 57 months) (p<0.05), whereas sex, age and smoking had no impact. No correlation was found between tHcy concentration and the number of vascular access thrombotic events; homozygotes for MTHFR had higher tHcy but no more vascular access thrombotic events. The 38 patients with a mean vascular access survival of less than 12 months (63 months) were compared to the 127 patients with a mean vascular access survival of >= 12 months (3925 months) (p<0.05): no difference in their respective tHcy concentrations before and after DiaVite introduction was found (3113 and 208 vs 3417 and 226 mol/L), but the first group presented more numerous synthetic fistulae (p<0.0001), lower hemoglobin levels, and higher erythropoietin doses. CONCLUSIONS. No significant association between hyperhomocysteinemia and vascular access thrombosis could be found in our population. DiaVite introduction allowed a significant reduction in tHcy, but had no impact on vascular access survival, except for a slight but not significant reduction in the prevalence of vascular access thrombotic events during the year on DiaVite. Potential benefits of approaches to reduce tHcy for vascular access time-life prolongation remain to be demonstrated.