Toward a Peritoneal Dialysis-First Policy in the United Kingdom and Europe

KEY POINTS: In a contemporary UK cohort of 96,809 patients, peritoneal dialysis was associated with lower mortality than hemodialysis across all phenotypes. The magnitude of this association varied by phenotype and attenuated with increasing age. Phenotype-based analyses may support more individualized dialysis modality selection and inform system-level policy decisions. BACKGROUND: Whether peritoneal dialysis (PD) is associated with lower mortality than hemodialysis in contemporary practice remains debated, particularly across heterogeneous patient populations and in the presence of competing transplantation. We examined modality-associated mortality differences across data-driven phenotypes of incident dialysis patients in the United Kingdom using a competing-risks framework. METHODS: We analyzed 96,809 adults initiating dialysis in the United Kingdom Renal Registry between 2007 and 2021. Unsupervised k-prototypes clustering was used to derive phenotypes based on age, sex, ethnicity, primary kidney disease, hemoglobin, serum albumin, and transplant-listing status. Mortality during the dialysis phase before transplantation was analyzed using competing-risks methods, treating kidney transplantation as a competing event. Cumulative incidence of death at 1 and 5 years was modeled using jack-knife pseudo-value regression with complementary log-log links, adjusting for demographic and clinical covariates. Dialysis modality (hemodialysis versus PD) was the primary exposure, with stratified analyses performed within each phenotype. A complementary competing-risks analysis examined time to transplantation. RESULTS: Among incident patients, 24% initiated PD and 76% hemodialysis. Three reproducible phenotypes were identified, differing primarily by age, hemoglobin and albumin levels, and transplant-listing status. Across the overall cohort, hemodialysis was associated with a higher cumulative incidence of death before transplantation at both 1 year (subdistribution hazard ratio [sHR], 1.85; 95% confidence interval [CI], 1.75 to 1.96) and 5 years (sHR, 1.47; 95% CI, 1.43 to 1.51). In stratified analyses, hemodialysis was associated with higher mortality across all phenotypes. At 1 year, adjusted sHRs ranged from 1.55 (95% CI, 1.44 to 1.68) to 2.29 (95% CI, 1.87 to 2.80) across clusters. At 5 years, the association persisted but attenuated with increasing age, with adjusted sHRs of 2.42 (95% CI, 2.23 to 2.63) in the youngest phenotype, 1.55 (95% CI, 1.48 to 1.61) in the intermediate phenotype, and 1.14 (95% CI, 1.11 to 1.19) in the oldest phenotype. In complementary analyses, time to transplantation did not differ significantly across phenotypes after adjustment. CONCLUSIONS: In contemporary UK practice, hemodialysis was associated with higher mortality during the dialysis phase compared with PD across distinct patient phenotypes, with time-dependent variation in effect magnitude. These registry-based associations support consideration of phenotype-informed modality selection while acknowledging the potential for residual confounding and the influence of health system context.