Link between poverty and kidney disease changes over time, shows study

Poverty is known to be a strong risk factor for end-stage kidney disease. Now, a first of-its-kind study has found that the association between poverty and kidney disease changes over time.

The percentage of adults beginning kidney dialysis who lived in zip codes with high poverty rates increased from 27.4 percent during the 1995-2004 time period to 34 percent in 2005-2010.

The study, by corresponding author Holly Kramer, MD, MPH and colleagues at Loyola University Chicago Stritch School of Medicine, is published in the journal Hemodialysis International.

Researchers examined data from the Centers for Medicare and Medicaid Services, as supplied by the US Renal Data System.

The Renal Data System does not provide data on incomes of individual dialysis patients. So researchers instead examined whether an individual patient lived in a poverty area, defined as a zip code in which at least 20 percent of the population lives below the federal poverty line.

The study demonstrated that, compared with the general population, adults beginning dialysis are more likely to be living in a poor zip code: 27.4 percent of adults beginning dialysis in 1995-2004 lived in poor zip codes, compared with 10.9 percent of the general population; the corresponding figures for 2005-2010 were 34 percent and 12.5 percent.

It remains unclear why living in a poor zip code is linked to end stage kidney disease. Some possibilities include access to health care, environmental toxin exposures that are more likely in poverty areas, and individual lifestyle factors, researchers wrote.
Future studies of end stage kidney disease patients should examine tends over time in poverty at the individual level and in smaller geographic areas, such as census tracts, Dr. Kramer and colleagues wrote.

"The collection of such data may help track national and local trends in poverty status and be used to develop policies for improving health outcomes and disease prevention," they wrote.