Propensity-Matched Mortality Comparison of Incident Hemodialysis and Peritoneal Dialysis Patients

Contemporary comparisons of mortality in matched hemodialysis and peritoneal dialysis patients are lacking. We aimed to compare survival of incident hemodialysis and peritoneal dialysis patients by intention-to-treat analysis in a matched-pair cohort and in subsets defined by age, cardiovascular disease, and diabetes. We matched 6337 patient pairs from a retrospective cohort of 98,875 adults who initiated dialysis in 2003 in the United States. In the primary intention-to-treat analysis of survival from day 0, cumulative survival was higher for peritoneal dialysis patients than for hemodialysis patients (hazard ratio 0.92; 95% CI 0.86 to 1.00, P = 0.04). Cumulative survival probabilities for peritoneal dialysis versus hemodialysis were 85.8% versus 80.7% (P < 0.01), 71.1% versus 68.0% (P < 0.01), 58.1% versus 56.7% (P = 0.25), and 48.4% versus 47.3% (P = 0.50) at 12, 24, 36, and 48 months, respectively. Peritoneal dialysis was associated with improved survival compared with hemodialysis among subgroups with age <65 years, no cardiovascular disease, and no diabetes. In a sensitivity analysis of survival from 90 days after initiation, we did not detect a difference in survival between modalities overall (hazard ratio 1.05; 95% CI 0.96 to 1.16), but hemodialysis was associated with improved survival among subgroups with cardiovascular disease and diabetes. In conclusion, despite hazard ratio heterogeneity across patient subgroups and nonconstant hazard ratios during the follow-up period, the overall intention-to-treat mortality risk after dialysis initiation was 8% lower for peritoneal dialysis than for matched hemodialysis patients. These data suggest that increased use of peritoneal dialysis may benefit incident ESRD patients.Hemodialysis and peritoneal dialysis differ profoundly, but randomized comparisons have so far proven impossible.¹ Despite obvious limitations, observational studies represent the next best design for survival comparisons. Although numerous studies have made peritoneal-dialysis-to-hemodialysis survival comparisons,^2–16 findings have not been entirely consistent.¹⁷ These survival comparisons are particularly salient in the United States, where mortality rates for hemodialysis patients are much higher than in Europe and in Japan,¹⁸ and peritoneal dialysis is used relatively little.^19,20 Because both modalities continue to evolve greatly from year to year, up-to-date survival comparisons may help inform the modality choices patients and physicians make when considering dialysis therapy. Comparative mortality studies of contemporary hemodialysis and peritoneal dialysis patients with similar comorbidity burdens are lacking.We used a matched-pair, retrospective cohort design to compare survival in adult patients initiating dialysis in the United States in 2003 with matching based on propensity of initial peritoneal dialysis use. Matching may reduce the influence of patients using one modality, who share few (if any) measured characteristics with patients using the other modality, because of contraindication or nonclinical forces.²¹ Our primary objective was to compare survival of incident dialysis patients, treated initially with hemodialysis or peritoneal dialysis, by intention-to-treat analysis in the matched-pair cohort. Secondary objectives were to compare survival across modalities in subsets defined by age, cardiovascular disease, and diabetes and to assess the sensitivity of inference to follow-up commencement (at dialysis initiation, at 90 days thereafter) and modality exposure definition (intention to treat, as-treated).