METHODS
We searched PubMed for studies published in English from 1966 to May 11, 2011, that described the personal and societal impact of OA based on data collected in the United States.First we searched PubMed for articles related to arthritis and OA using standard epidemiologic and health care–burden indicators: prevalence, incidence, mortality, morbidity, lifetime risk, risk factors, ambulatory care, and hospitalization. We searched both arthritis and OA for two reasons: the terms are sometimes used interchangeably, and a public health approach measures all types of arthritis combined. Also, we identified agencies and organizations whose focus is population-health epidemiology (the National Center for Health Statistics), health service use (the Agency for Healthcare Research and Quality [AHRQ]), or delivery of care to people with OA (the American College of Rheumatology and the American Academy of Orthopaedic Surgeons) and searched their Web sites for reports using the terms listed above. Then we reviewed materials such as journal articles to identify those that met the search criteria.