Epidemiologic trends in chronic renal replacement therapy over forty years: A Swiss dialysis experience

BACKGROUND: Long term longitudinal data are scarce on epidemiological characteristics and patient outcomes in patients on maintenance dialysis, especially in Switzerland. We examined changes in epidemiology of patients undergoing renal replacement therapy by either hemodialysis or peritoneal dialysis over four decades. METHODS: Single center retrospective study including all patients which initiated dialysis treatment for ESRD between 1970 and 2008. Analyses were performed for subgroups according to dialysis vintage, based on stratification into quartiles of date of first treatment. A multivariate model predicting death and survival time, using time-dependent Cox regression, was developed. RESULTS: 964 patients were investigated. Incident mean age progressively increased from 48 ± 14 to 64 ± 15 years from 1(st) to 4(th) quartile (p < 0.001), with a concomitant decrease in 3- and 5-year survival from 72.2 to 67.7%, and 64.1 to 54.8%, respectively. Nevertheless, live span continuously increased from 57 ± 13 to 74 ± 11 years (p < 0.001). Patients transplanted at least once were significantly younger at dialysis initiation, with significantly better survival, however, shortened live span vs. individuals remaining on dialysis. Among age at time of initiating dialysis therapy, sex, dialysis modality and transplant status, only transplant status is a significant independent covariate predicting death (HR: 0.10 for transplanted vs. non-transplanted patients, p = 0.001). Dialysis vintage was associated with better survival during the second vs. the first quartile (p = 0.026). DISCUSSION: We document an increase of a predominantly elderly incident and prevalent dialysis population, with progressively shortened survival after initiation of renal replacement over four decades, and, nevertheless, a prolonged lifespan. Analysis of the data is limited by lack of information on comorbidity in the study population. CONCLUSIONS: Survival in patients on renal replacement therapy seems to be affected not only by medical and technical advances in dialysis therapy, but may mostly reflect progressively lower mortality of individuals with cardiovascular and metabolic complications, as well as a policy of accepting older and polymorbid patients for dialysis in more recent times. This is relevant to make demographic predictions in face of the ESRD epidemic nephrologists and policy makers are facing in industrialized countries.