| Abstract: | ![]()
Background and objectives: The aim of the investigation presented here was to compare the rates, causes, and timing of cardiovascular (CV) death in incident peritoneal dialysis (PD) and hemodialysis (HD) patients.Design, setting, participants, & measurements: The study included all adult Australian and New Zealand patients commencing dialysis between January 1, 1997 and December 31, 2007. Rates of and times to CV death were compared by incident rate ratios, cumulative incidence, and multivariable Cox proportional hazards model analyses. Dialysis modality was included in the model as a time-varying covariate, and a competing risks approach was used to obtain cause-specific hazard ratios.Results: Of the 24,587 patients who commenced dialysis (first treatment PD n = 6521; HD n = 18,066) during the study, 5669 (21%) died from CV causes [PD 2044 (28%) versus HD 3625 (21%)]. The incidence rates of CV mortality in PD and HD patients were 9.99 and 7.96 per 100 patient-years, respectively (incidence rate ratio PD versus HD, 1.25; 95% confidence interval 1.12 to 1.32). PD was consistently associated with an increased hazard of CV death compared with HD after 1 yr of treatment. This increased risk in PD patients was largely accounted for by an increased risk of death due to myocardial infarction.Conclusions: Dialysis modality is significantly associated with the risk, causes, and timing of CV death experienced by ESRD patients in Australia and New Zealand.Cardiovascular disease (CVD) represents the leading cause of death in dialysis patients, accounting for up to 40% of deaths in Australia, New Zealand, and the United States (1,2). Individuals with chronic kidney disease (CKD) have up to a 10- to 20-fold greater risk of cardiac death than age- and sex-matched controls without CKD (3,4). Once dialysis patients develop cardiac events, they are significantly less likely to receive important interventions and are far more likely to die than patients without CKD (5).The increased incidence of CVD in dialysis patients is only partially explained by an increased prevalence of traditional risk factors, such as hypertension, diabetes mellitus, dyslipidemia, smoking, obesity, and physical inactivity (6,7). Additional risk may be conferred by nontraditional factors that are frequently observed in advanced CKD, such as hyperhomocysteinemia, anemia, abnormal calcium/phosphate metabolism, inflammation, malnutrition, oxidative stress, and elevated lipoprotein(s) (6,8–11).There is limited evidence that dialysis modality may also influence CVD risk. Bleyer et al. (12) observed an increased risk of cardiac death in hemodialysis (HD) patients immediately after weekends, possibly related to the more frequent occurrence of hyperkalemia and fluid overload at this time. In contrast, the continuous nature of peritoneal dialysis (PD) may potentially minimize cardiovascular risk related to fluctuations in body fluid and electrolyte compositions. HD patients may also be exposed to a greater risk of CVD compared with PD patients as a result of more rapid loss of residual renal function (13,14) and more hyperdynamic circulation conferred by the presence of an arteriovenous fistula and extracorporeal circulation (15). On the other hand, PD patients are exposed to greater amounts of glucose in dialysate, leading to a much higher prevalence of insulin resistance, dyslipidemia, and metabolic syndrome (16). There is also evidence that PD patients exhibit greater coagulability, possibly related to dyslipidemia (17). Despite observed differences in known CVD risk factors between PD and HD patients, there has been little study to date of the influence of dialysis modality on CVD risk. Kennedy et al. (6) observed that PD was of borderline statistical significance (P = 0.06) as an independent predictor of carotid atherosclerosis in stage 5 CKD. Previous registry studies have shown conflicting results with respect to the influence of dialysis modality on all-cause mortality (reviewed in reference 18), but none have specifically examined cardiovascular mortality. Moreover, many of these studies have suffered from serious limitations, such as inclusion of prevalent patients, use of proportional versus nonproportional hazards models, single-center design, data coding ambiguity, use of outdated data, dialysis modality selection bias, lack of adjustment for demographic and clinical variables, and residual confounding (18). The aim of the study presented here was to evaluate the effects of dialysis modality on the frequency, types, and causes of cardiovascular mortality in a large, incident, ESRD population. |
