Dialysis modality and survival in octogenarians: real-world population-based cohort study

Abstract Background Evidence guiding dialysis modality decisions in very elderly patients is limited, and real-world outcomes remain poorly characterized. This study evaluates long-term survival in octogenarians initiating kidney replacement therapy (KRT) by dialysis modality. Methods We used data from the Catalan Renal Registry to identify all patients aged ≥80 years who started dialysis between 2000 and 2022. Patients were classified according to initial dialysis modality (hemodialysis [HD] vs peritoneal dialysis [PD]). A 1:3 propensity score-matched analysis was performed. Transition from PD to HD was modeled as a time-dependent covariate in Cox proportional hazards models to account for modality switching and minimize immortal time bias. Results Among 4205 octogenarians, 239 initiated PD, 3966 initiated HD. After matching, 213 PD patients were compared to 637 HD controls. Five-year survival did not differ significantly by initial modality after adjustment. However, switching from PD to HD was independently associated with increased mortality (HR 1.46; 95%CI 1.02–2.08; p=0.038), suggesting a potential association with clinical deterioration. PD without switching was not significantly associated with mortality (HR 1.19; p = 0.120; 95%CI 0.95-1.48). Older age and KRT initiation in 2000–2007 were also associated with worse outcomes. Conclusions In this large population-based cohort of octogenarians, initial dialysis modality was not associated with differences in survival after adjustment. However, transition from PD to HD was associated with higher mortality, underscoring the importance of dynamic monitoring and ongoing clinical reassessment in peritoneal dialysis.