Survey Data Often Understate True Disease Prevalence and Sometimes Vastly Overstate Its Growth

ANN ARBOR, Mich.--()--Disease prevalence estimates that rely solely on responses to surveys inquiring about treatment or diagnosis tend to understate true prevalence and obscure prevalence trends. For example, treated diabetes prevalence was less than half of true prevalence in 1999-2000. Over the ensuing twelve years, the rate of increase in treated prevalence was more than 50 percent higher than that of true prevalence.

These are the results from a study on the prevalence of diabetes, hypertension, and hyperlipidemia found in today’s release of Health Affairs, written by Charles Roehrig and Matt Daly from Altarum Institutes’ Center for Sustainable Health Spending.

The study, funded by the Robert Wood Johnson Foundation, spanned the years 1999-2012 and employed a combination of survey responses and laboratory test results from the National Health and Nutrition Examination Survey.

The authors found that treated prevalence understated true prevalence for each of the three medical conditions studied. However, the degree of understatement declined over time, as growing shares of people with each condition gained treatment. As a result, the rate of growth in treated prevalence exceeded that of true prevalence, by a factor of two for diabetes, a factor of three for hypertension, and a factor of fifty for hyperlipidemia.

“These findings show that one must be careful in interpreting survey data on disease prevalence,” said Charles Roehrig, an author of the study. “It also suggests that the high rate of growth in spending on diabetes, hypertension, and hyperlipidemia during the study period should come down over time as the growth in treated prevalence necessarily falls toward that of true prevalence.”

You can find the full study in the latest edition of Health Affairs at http://www.healthaffairs.org/ or @health_affairs.

Altarum Institute (www.altarum.org) integrates objective research and client-centered consulting skills to deliver comprehensive, systems-based solutions that improve health and health care. Altarum employs almost 400 individuals and is headquartered in Ann Arbor, Mich., with additional offices in the Washington, D.C., area; Portland, Maine; and San Antonio, Texas.

Contacts

Altarum Institute
Ken Schwartz, 202-772-5062
ken.schwartz@altarum.org

Contacts

Altarum Institute
Ken Schwartz, 202-772-5062
ken.schwartz@altarum.org