Study Shows Regional Variations in Dialysis Initiation among ESRD Patients

People with end-stage renal disease (ESRD) who live in the United States Midwest are more likely to begin dialysis treatment much earlier than their counterparts who live in southern, eastern, and western states, according to a geographical study presented during Kidney Week 2012 in San Diego.

“We expected to see variation across the country, but we didn’t expect to see the concentration in the Midwest,” said lead researcher Julia Scialla, MD, assistant professor of medicine at the University of Miami.

The study sought to explore geographical aspects of variability of a 20-year trend that has seen initiation of dialysis begin at an earlier stage of disease when patients have increasingly higher levels of estimated glomerular filtration rate (eGFR), despite a lack of evidence that patients who begin the treatment earlier fare any better than those who don’t, said Scalia. A decrease of eGFR precedes onset of kidney disease and is measured to determine severity of decline of kidney function of dialysis patients.

Data on dialysis patients over the past two decades indicate that their GFR levels at the time dialysis is initiated has continued to rise, indicating that the treatment is being started earlier and earlier with passing years. “That’s why we were interested in how that may vary across the country,” Scallia said.

Researchers identified 310,962 adult patients in the US Renal Data System ESRD database who began dialysis from 2006 to 2008 within 805 health service areas connected by mostly local geography of cities and counties. They used CMS Form 2728 to gather further information about the patients, such as demographics, comorbidity, serum creatinine, and estimated patient GFR at the point at which dialysis was initiated, Scialla said. Then they plotted mean eGFR at HSA levels to map geographical patterns.

Results from the study revealed that mean eGFR at the time dialysis was initiated showed a regional pattern. “There were some regions of the country where the eGFR was higher and other regions where the eGFR was lower. Some regions of the country were clearly earlier and that’s what we were trying to understand,” Scallia said.

The upper Midwest had higher numbers, an indication that the timing of dialysis initiation began earlier, while the Southeastern US had lower numbers, indicating a later initiation, noted Scallia. Still up for debate, she said, is an accepted definition of what specifically is too early to begin dialysis. “No one can say for sure, but certainly it’s not consistent across the country,” said Scallia.

The reasons for the geographical differences are unknown but may be the focus of future studies. “We want to look at characteristics of physicians. The guidelines have changed and we think younger physicians are probably initiating (dialysis) earlier. We also think differences in nephrologists in terms of age and when they completed training and current affiliation with academic centers may influence their practice patterns,” said Scallia.

Other possibilities worthy of exploring include preference among patients and their health insurance providers, Scialla said.

Study limitations included possible errors in the CMS forms used for data mining, inaccurate serum creatinine, under-reporting of comorbidity, and that some of the health groups involved in the study had a limited incidence of dialysis.