Care Continuity, Nephrologists' Dialysis Facility Preferences, and Outcomes.

Importance: Patients may initiate dialysis at their predialysis nephrologists' primary facilities (ie, where the nephrologist saw the most patients) to preserve continuity of care, even if the facilities are of low quality. Patients from minoritized racial and ethnic groups may be the most negatively impacted. Objective: To examine starts at nephrologists' primary facilities, downstream outcomes, and racial disparities in dialysis start quality. Design, Setting, and Participants: This cohort study used Medicare administrative data of patients initiating dialysis at freestanding US dialysis facilities from January 1, 2015, to October 31, 2020, with 1 year of follow-up (ending October 31, 2021). Analyses concluded January 26, 2025. Participants were adults with fee-for-service Medicare initiating dialysis. Exposures: Quality of nephrologists' primary facilities (using publicly available 5-star ratings) and primary facilities' proximity to patients. Main Outcomes and Measures: The primary outcomes were starting dialysis at the nephrologist's primary facility (ie, primary facility starts), whether the starting facility was high quality (ie, 4-star or 5-star ratings), mortality and hospitalization rates, and racial and ethnic disparities in high-quality primary facilities and in starting dialysis at high-quality facilities. Analyses used multivariable linear and Poisson regression with hospital service area fixed effects (unique intercepts for each area). Results: Of 143 776 adults (median [IQR] age, 73 [67-79] years; 64 447 female [45%]; 4989 Asian [3%]; 28 515 Black [20%]; 11 296 Hispanic [8%]; 96 639 non-Hispanic White [67%]), 64 186 (45%) had managing nephrologists with high-quality primary facilities. Primary facility starts were lower as the primary facility's quality increased (0.5 percentage points [pp] lower for every 1-star increase in rating; 95% CI, 0.1-0.8 pp; P = .03). In contrast, primary facility starts were 33.9 pp (95% CI, 33.0-34.9 pp; P < .001) more likely when primary facilities were close to patients than when distant. Each additional quality star in nephrologists' primary facility was associated with more 4-star or 5-star facility starts (7.4 pp; 95% CI, 6.9-7.9 pp) and 4.5 fewer hospitalizations per 100 person-years (95% CI, 2.8-6.1 hospitalizations per 100 person-years). Compared with White patients, Black patients were 2.8 pp (95% CI, 1.7-3.9 pp) less likely to start at 4-star or 5-star facilities and 2.0 pp (95% CI, 1.0-3.0 pp) less likely to be treated by nephrologists with 4-star or 5-star primary facilities. Conclusions and Relevance: Primary facility starts were common even when they were low quality, and outcomes were worse when nephrologists had low-quality primary facilities. Black patients disproportionately start dialysis at low-quality facilities and are less likely to have nephrologists with high-quality primary facilities. Policies that promote improved access to high-quality dialysis facilities may be necessary to alleviate these disparities.