Geographic Dialysis Facility Density and Early Dialysis Initiation.

Importance: The decision of when to start maintenance hemodialysis may be affected by health system-level support for high-intensity care as manifested by area dialysis facility density. Yet an association between early hemodialysis initiation and higher area density of dialysis facilities has not been shown. Objective: To examine whether there is an association between area dialysis facility density and earlier dialysis initiation. Design, Setting, and Participants: Cross-sectional analysis was conducted of publicly reported claims and geographic-based population data collected in the Medical Evidence files of the US Renal Data System (USRDS), a comprehensive registry of all patients initiating hemodialysis in the US, from calendar years 2011 through 2019. Data were linked to the American Community Survey, using residential zip codes, and then to health service area (HSA) primary care and hospitalization benchmarks, using the Dartmouth Atlas crosswalk. Data were analyzed from November 1, 2021, to August 31, 2023. Exposure: Dialysis facility density at the level of HSA (number of dialysis facilities per 100 000 HSA residents) split into 5 categories. Main Outcomes and Measures: The odds of hemodialysis initiation at an estimated glomerular filtration rate (eGFR) greater than 10 mL/min/1.73 m2 vs less than or equal to 10 mL/min/1.73 m2. Results: Hemodialysis was initiated in a total of 844 466 individuals at 3397 HSAs at a mean (SD) eGFR of 8.9 (3.8) mL/min/1.73 m2. Their mean (SD) age was 63.5 (14.7) years, and 484 346 participants (57.4%) were men. In the HSA category with the highest facility density, individuals were younger (63.3 vs 65.2 years in least-dense HSAs), poorer (mean percent of households living in poverty, 10.4% vs 8.4%), and more commonly had a higher percentage of Black individuals (40.6% vs 11.3%). More individuals in the dialysis-dense HSAs than least-dense HSAs had diabetes (60.1% vs 58.5%) and fewer had access to predialysis nephrology care (60.8% vs 64.1%); the rates of heart failure and immobility varied, but not in a consistent pattern, by HSA dialysis density. The mean (SD) facility density was 4.1 (1.89) centers per 100 000 population in the most dialysis-dense HSAs. Compared with patients in HSAs with a mean of 1.0 per 100 000 population, the odds of hemodialysis initiation at eGFR greater than 10 mL/min/1.73 m2 were 1.07 (95% CI, 1.03-1.11) for patients in the densest HSAs, and compared with HSAs with 0 facilities, the odds of early hemodialysis initiation were 1.06 (95% CI, 1.02-1.10) for patients in the densest HSAs. Conclusions and Relevance: In this cross-sectional study of USRDS- and HSA-level data, HSA dialysis density was associated with early hemodialysis initiation.