Nephrologist Affiliation With Dialysis Facilities and Patient Trajectories in End-Stage Kidney Disease.

Importance: Across the treatment modalities for end-stage kidney disease (ESKD), kidney transplantation offers the best survival and quality-of-life outcomes, yet most patients are unable to receive a transplant, making dialysis the most common long-term treatment option. Despite its advantages, home peritoneal dialysis (PD) use remains limited in the US, with financial incentives potentially contributing to this underutilization. Objective: To examine the association between nephrologist affiliation with dialysis facilities and facility characteristics, including profit status and PD service offerings, with 2 critical ESKD outcomes: PD catheter placement and kidney transplant surgery. Design, Setting, and Participants: This retrospective cohort study was conducted using claims data from Medicare beneficiaries with ESKD who initiated dialysis between 2013 and 2022, with follow-up through 24 months after dialysis initiation. Data were analyzed from January 1, 2024, to December 31, 2025. Exposure: Nephrologist affiliation with dialysis facilities, determined by whether a nephrologist submitted any outpatient claims from a Medicare-certified dialysis facility. Main Outcomes and Measures: Outcomes included PD catheter placement and kidney transplant surgery within 24 months of dialysis initiation. Adjusted 24-month cumulative incidences and risk differences were estimated using a doubly robust survival targeted maximum likelihood estimation framework. Results: Among the 28 040 beneficiaries (mean [SD] age, 70.6 [10.8] years; 56.8% male) included in this study, 24 301 (86.7%) were attributed to affiliated nephrologists. The mean (SD) follow-up time was 322 (307) days. The adjusted 24-month cumulative incidence of PD catheter placement was 9.9% for patients of affiliated nephrologists compared with 8.2% for patients of nonaffiliated nephrologists (adjusted difference, 1.7 percentage points [pp] [95% CI, 0.6-2.8 pp]; P = .01). In stratified models, the adjusted difference in PD catheter placement was larger for nephrologists affiliated with for-profit facilities (1.9 pp [95% CI, 0.8-3.0 pp]; P = .01) and for those affiliated with facilities offering PD (2.0 pp [95% CI, 0.8-3.2 pp]; P = .01). Differences in kidney transplant surgery within 24 months were small and not statistically significant. Conclusions and Relevance: In this retrospective cohort study of Medicare beneficiaries initiating dialysis, nephrologist affiliation with dialysis facilities, especially for-profit centers or centers offering PD, was associated with a higher 24-month cumulative incidence of PD catheter placement, while the cumulative incidence of kidney transplant surgery within 24 months did not differ meaningfully by affiliation. These findings underscore the potential role of economic and organizational factors in promoting PD, and they highlight the need for policy reforms that expand home-based dialysis while preserving equitable access to transplantation.