TY - JOUR T1 - Estimating Disease Prevalence and Incidence Using Administrative Data: Some Assembly Required JF - The Journal of Rheumatology JO - J Rheumatol SP - 1241 LP - 1243 DO - 10.3899/jrheum.130675 VL - 40 IS - 8 AU - MICHAEL M. WARD Y1 - 2013/08/01 UR - http://www.jrheum.org/content/40/8/1241.abstract N2 - The prevalence and incidence of a disease are among the most fundamental measures in epidemiology. Prevalence is a measure of the burden of disease in a population in a given location and at a particular time, as represented in a count of the number of people affected. Counts of the number of people with a disease are required to plan appropriately for their healthcare needs. For example, large numbers of patients with rheumatoid arthritis will necessitate training and staffing with more rheumatologists than if the number of patients with the disease was low; similarly, having many patients with osteoarthritis will require more orthopedic surgeons and surgical beds.Prevalence estimates, which adjust these counts to the size of the source population, are also useful clinically in providing context for diagnostic decision making. Knowing that coronary artery disease is much more common than myocarditis is helpful in evaluating patients with anterior chest pain. Prevalence may also be used to compare disease burden across locations or time periods. However, because prevalence is determined by not only the number of persons affected but also their survival, prevalence is a less useful measure than incidence rates in studies of etiology. Incidence rates represent the number of new cases of disease among the number of susceptible persons in a given location and over a particular span of time. The primary value of incidence rates is in studies of disease etiology, by comparing how the rates vary among different subgroups or with different exposures.To provide prevalence and incidence rate estimates that are both reliable and generalizable, studies must include a sample large enough to capture most (if not all) cases and sufficiently distributed, both geographically and sociologically, to be representative of the general population. With uncommon diseases, including most autoimmune rheumatic diseases, the challenge is multiplied … Address correspondence to Dr. M. Ward, Building 10 CRC, Room 4-1339, 10 Center Drive, Bethesda, MD 20892-1468. E-mail: wardm1{at}mail.nih.gov ER -