Dialysis Facility Density, Timing of Dialysis Initiation

Over the past decade, the prevalence of kidney failure has doubled in the United States, with substantial cost implications for the US health care system. In the absence of a formalized threshold of estimated glomerular filtration rate (eGFR) below which hemodialysis is recommended nationwide, there is wide variability in the timing of initiation of dialysis across the country. 

Results of a previous study suggested that 11.4% of the variability attributed to physician decision-making in eGFR at dialysis initiation occurred across physicians, while 88.6% occurred within physicians. Most of the variability was explained by patient case mix. In another study of older veterans receiving care through Medicare versus the Veterans Health Administration (VA), with Medicare providing higher reimbursements to physicians for dialysis services than the VA, a higher proportion of patients who received predialysis kidney care via Medicare initiated dialysis compared with those who received predialysis care in the VA system. 

VagishHemmige, MD, MS, and colleagues conducted a cross-sectional data analysis to examine whether there is an association between area dialysis facility density and early initiation of dialysis. Results were reported in JAMA Network Open. 

The analysis utilized data from the US Renal Data System from the calendar years 2011 through 2019. Those 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 analysis was conducted from November 1, 2021, to August 31, 2023. 

The analysis exposure was density of dialysis facilities at the level of HSA (the number of dialysis facilities per 100,000 HSA residents) split into five categories. Category 1 had zero facilities, category 2 represented HSAs with more than zero and less than the 25th percentile of facility densities, category 3 represented the 25th and less than the 50th percentile of facility densities, category 4 represented the 50th and less than the 75th percentile of facility densities, and category 5 represented the highest facility densities, or the 75th or greater percentile. The main outcomes and measure were the odds of initiation of hemodialysis at an eGFR greater than 10 mL/min/1.73 m² versus less than or equal to 10 mL/min/1.73 m². 

There were 3397 HSAs and 844,466 patients receiving incident hemodialysis between 2011 and 2019 who met the study inclusion criteria. Of those, 42.6% were women (n=360,120) and 57.4% were men (n=483,346). Mean age was 63.5 years, 28.1% were Black, and 15.1% were Hispanic. Thirty percent of the overall cohort had heart failure and 59.1% had diabetes; 24.1% had no nephrology care prior to developing kidney failure. Most (80.5%) initiated dialysis with a catheter. 

The mean facility density was 4.1 centers per 100,000 population in the most dialysis-dense HSAs. Median HSA-level dialysis facility density nationwide was 1.95 centers per 100,000 population. Dialysis-dense HSAs, defined as those with the highest density of dialysis facilities and dialysis stations within facilities, were located primarily in areas of the Midwest and Southeast. The mean eGFR at which dialysis was initiated between 2011 and 2019 was 8.9 mL/min/1.73 m². Those who initiated hemodialysis in the most dialysis-dense HSA category were younger (63.3 vs 65.2 years in categories 5 vs 1 of HSA-level dialysis facility density), more commonly women (44.4% vs 41.3%), more commonly Black (40.6% vs 11.3%), and had a higher proportion with diabetes (60.1% vs 58.5%), alcohol or drug use disorder (2.9% vs 2.5%), and cerebrovascular disease (9.8% vs 9.2%) than those in the least dialysis-dense HSAs. 

In multivariable models with eGFR as a continuous variable, 10% of the total variability of mean eGFR at dialysis initiation was explained by the HSA-level characteristics. There was an association of odds increasing by progressively higher-density categories between HSA-level dialysis facility density and odds of early hemodialysis initiation (eGFR greater than 10 mL/min/1.73 m²). 

There was a 1.06-higher odds (95% CI, 1.02-1.11; P=.004) of initiating hemodialysis in the highest-density HSAs compared with HSAs with zero dialysis facilities and a 1.07-higher odds (95% CI, 1.06-1.07; P<.001) of initiating hemodialysis in the highest-density HSAs compared with category 2 of HSA-based dialysis facility density, where the mean density was 1.0 facilities per 100,00 residents. 

Across all HSA types, Black patients initiated hemodialysis at a significantly lower eGFR than patients of other races. The researchers stratified by individual race, and, in subgroup analyses, there was a significant association between HSA-level dialysis facility density and odds of dialysis initiation at an eGFR greater than 10 mL/min/1.73 m² in White patients, with higher odds of initiating at an eGFR greater than 10 mL/min/1.73 m²: 1.08 (95% CI, 1.04-1.12; P<.001) in unadjusted models and 1.05 (95% CI, 1.00-1.10; P=.03) in adjusted models in the highest-density HSAs compared with HSAs with zero dialysis facilities. In Black patients, there were also higher odds of dialysis initiation at an eGFR greater than 10 mL/min/1.73 m², but the finding was not statistically significant (odds ratio, 1.03; 95% CI, 0.94-1.13; P=.50). 

There were some limitations to the findings cited by the authors, including the inability to account for patients who did not initiate hemodialysis when indicated and the inability to determine the degree to which distance from dialysis facilities was associated with eGFR at dialysis initiation. 

In summary, the researchers said, “In this cross-sectional study, HSA-based higher density of dialysis facilities was associated with earlier dialysis initiation among an incident kidney failure population. This finding lends support to the notion that dialysis facility saturation of HSAs may represent practice patterns that affect timing of hemodialysis initiation.” 

Source: JAMA Network Open