TIME TRENDS OF DISEASE PREVALENCE AMONG OLDER U.S. ADULTS

I. Akushevich, J. Kravchenko, A. Yashkin, F. Sloan, A.I. Yashin, Duke University, Durham, North Carolina

Longer lifespan is accompanied by a larger number of chronic diseases among older adults. Combined with the growing proportion of older adults in the population, this brings the problem of age-related multimorbidity to the forefront as a major contributor to rising medical expenditures. A detailed study on nationally representative time trends of multiple conditions can provide new quantitative information about the dynamics of disease prevalence among older U.S. adults. We evaluated the time trends of prevalence of 48 acute and chronic diseases common among older U.S. adults (aged 65+) and death hazard ratios (HRs) of individuals with these conditions using the Medicare 5% (1991-2012) and SEER-Medicare data files (1992-2007). The age-adjusted prevalence of most cardiovascular diseases and malignancies as well as chronic renal and liver diseases, diabetes, hip fracture, and arthritis increased over time. Since death HRs decreased for these diseases, the trends could be explained, in part, by improved ascertainment. Most alarming were the trends in pancreatic cancer, Alzheimer’s disease, and weight deficiency which showed an annual percentage change (APC) of prevalence rates of 1.5-2.5% combined with increasing HRs (APC=1.6-2.1%). Conversely, prevalence of myocardial infarction, pneumonia, and peptic ulcer decreased over time. These estimates, obtained using nationally representative Medicare data, are timely and highly demanded by both physicians and public health specialists. The results have clear interpretation and practical application, e.g., they create a basis for constructing a novel multimorbidity index adjusted for patients aged 65+ that can be used in clinical practice and for forecasting future medical expenditures.