Affiliations: [a] Center for Health Policy, Sanford Duke School of Public Policy, Duke University, Durham, NC, USA | [b] Department of Community and Family Medicine, Duke University Medical Center, Durham, NC, USA | [c] Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA | [d] Institute for Social Research, University of Michigan, Ann Arbor, MI, USA | [e] Program in Epidemiology of Dementia, Duke University Medical Center, Durham, NC, USA
Correspondence:
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Corresponding author: Donald H. Taylor, Jr. Ph.D., Duke University, 302 Towerview Rd, Rubenstein Hall 112, Durham, NC 27708, USA. Tel.: +1 919 613 9357; E-mail: don.taylor@duke.edu.
Abstract: Our study estimates the sensitivity and specificity of Medicare claims to identify clinically-diagnosed dementia, and documents how errors in dementia assessment affect dementia cost estimates. We compared Medicare claims from 1993–2005 to clinical dementia assessments carried out in 2001–2003 for the Aging Demographics and Memory Study (ADAMS) cohort (n = 758) of the Health and Retirement Study. The sensitivity and specificity of Medicare claims was 0.85 and 0.89 for dementia (0.64 and 0.95 for AD). Persons with dementia cost the Medicare program (in 2003) $7,135 more than controls (P < 0.001) when using claims to identify dementia, compared to $5,684 more when using ADAMS (P < 0.001). Using Medicare claims to identify dementia results in a 110% increase in costs for those with dementia as compared to a 68% increase when using ADAMS to identify disease, net of other variables. Persons with false positive Medicare claims notations of dementia were the most expensive group of subjects ($11,294 versus $4,065, for true negatives P < 0.001). Medicare claims overcount the true prevalence of dementia, but there are both false positive and negative assessments of disease. The use of Medicare claims to identify dementia results in an overstatement of the increase in Medicare costs that are due to dementia.
