Effect of the duration of dialysis on survival in a cohort of chronic haemodialysis patients

Background. Atherosclerosis and vascular calcification are common in chronic haemodialysis (HD) patients, and usually progress with time. Whether the length of dialysis treatment in chronic HD patients is a significant independent risk factor of death is not clear. Methods. A cohort of chronic HD patients from the Okinawa Dialysis Study, ii = 1243(720 men. 523 women), was followed from January 1991 to December 2000, and their survival rates were compared against the duration of HD, which was calculated in months from the start of dialysis therapy to January 1991. A Cox proportional hazards regression analysis was done to examine the influence of the duration of dialysis on survival, after adjusting for other factors such as age, sex. serum albumin concentration and diastolic blood pressure. The hazards ratio and 95% confidence interval (CI) were calculated in both diabetic and non-diabetic patients. Results. The mean duration of dialysis was 61.9 months and ranged from 1 to 233 months. The numbers of patients who died, underwent renal transplantation or were transferred outside Okinawa were 568 (45.7%). 61 (4.9%) and 14 (1.1%), respectively. during the study. The hazards ratio (95% Cl) was 1.002 (1.000. 1.004, P=0.0245) for non-diabetic patients and 1.006 (1.001 1.011, P=0.0214 for diabetic patients, suggesting that the longer the duration of dialysis, the greater the risk of death. Conclusions. This study shows that prolonged dialysis is a significant predictor of death in chronic HD patients, in particular diabetic patients. Whether this is related to the progression of the atherosclerotic process or to uraemic conditions remains to be shown.