Patient selection affects end-stage renal disease outcome comparisons

Geographic differences in dialysis patient outcome could be partially explained by demographic and baseline comorbid characteristics, including cardiovascular disease. To evaluate the influence of patient selection on outcome comparisons, we focus on the effect of cardiovascular disease on ESRD patient outcome using data from the Lombardy Registry. A total of 4139 ESRD patients (aged 61.9 +/- 15.6 years, males 60.5%, diabetics 20%) who started renal replacement therapy (RRT) between 1994 and 1997 were considered. The analysis of 4-year survival in the presence or absence of ischemic heart disease and congestive heart failure at the beginning of RRT was performed using cardiovascular mortality and mortality from any cause as endpoints. Survival was compared by means of the Cox regression proportional hazard model; explanatory covariates were age,gender and diabetic status. Of the patients considered for the study, 918 (22.2%) died during the 4-year follow-up; the main cause of death was cardiovascular disease (cardiac causes in 304 patients [33.1%], vascular causes in 88 patients [9.6%.]). Patients with ischemic heart disease at the beginning of RRT had significantly higher mortality from myocardial infarction or from any cause than those without. The mortality risk for myocardial infarction was higher for elderly (RR = 1.04 per year; P = 0.0001) and diabetic patients (RR = 2.19; P = 0.0006). Chronic heart failure strongly affected overall mortality but not that from myocardial infarction. Ischemic heart disease and chronic heart failure are very common in incident ESRD patients and their presence is an important determinant of survival. Particular interventions are needed to prevent the development of cardiac abnormalities starting as early as possible during the predialytic phase.