As the most common arthritis and a leading cause of chronic disability, osteoarthritis is associated with substantial cost to the individual and to society. Epidemiologic studies have supplied, in addition to incidence, prevalence and risk factor data, much of what is known about the natural history of osteoarthritis.
Especially given the anticipated increase in osteoarthritis prevalence, the need to identify risk factors for incident osteoarthritis, osteoarthritis progression, osteoarthritis-associated physical function decline, and disability is a high priority. As this review illustrates, the emphasis has shifted in osteoarthritis epidemiology towards the identification of risk factors for osteoarthritis progression rather than incidence.
Several risk factors for progression are emerging, many of which are impairments or pathology in the local joint organ environment. This shift in focus relates in part to the concept that local risk factors might ultimately be targeted to delay osteoarthritis progression or to enhance the effect of a disease-modifying drug.
Division of Rheumatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Correspondence to Leena Sharma, MD, Division of Rheumatology, Feinberg School of Medicine, Northwestern University, 240 E Huron Street, McGaw M-300, Chicago, IL 60611, USA Tel: +312 503 8003; fax: +312 503 0994; e-mail: L-Sharma@northwestern.edu