Outcomes of Dialysis Modality Switch: A Matched Cohort Analysis from a National Renal Replacement Therapy Registry, 2010–2022

Background/Objectives: Evidence on mortality after dialysis modality switch is inconsistent and may vary by timing and type of switch. This study examined associations between modality switch and short- and long-term mortality and compared cause-of-death patterns across groups. Methods: This matched historical cohort study used the Israeli National Renal Replacement Therapy Registry (2010–2022). Adult dialysis patients with a modality switch were matched 1:1 to non-switchers by age, initial modality, and survival to switch time. Follow-up started at the switch date or matched index date. Outcomes were all-cause mortality at 3 months, 6 months, 1 year, and 2 years. Conditional Cox models estimated adjusted hazard ratios overall, by initial modality, and by early (≤180 days) or late switch. Among 2-year decedents, logistic regressions compared primary and multiple cause-of-death distributions. Results: The cohort included 892 switchers and 892 non-switchers (median age 65.0 years; 66.1% males; 64.2% peritoneal dialysis [PD]-first). Among PD-first late switchers, mortality hazards were lower across follow-up landmarks, with the greatest reduction at 2 years (HR 0.421; 95%CI: 0.306–0.579), whereas hemodialysis (HD)-first early switchers had higher mortality, with borderline significance (HR 1.614; 95%CI: 0.951–2.740). Among 591 deaths within 2 years, primary cause-of-death distributions were similar; for multiple causes, early switchers showed higher adjusted odds of heart disease, whereas late HD-initiated switchers had higher adjusted odds of renal disease. Conclusions: Mortality after modality switch varies by transition direction and timing. Specifically, a late PD-to-HD transition was associated with lower long-term mortality. Further studies are needed to clarify the roles of clinical/transition-related factors.