British Columbia has seen an increase in the incidence of physician-reported osteoarthritis (OA) in men and women due to population aging, with an additional increase beyond the effect of aging in women.

"The number of people with arthritis is expected to increase as the population ages," Dr. Jacek A. Kopec, of the University of British Columbia, Canada, and colleagues write in the July 15 issue of Arthritis and Rheumatism. "To our knowledge, there have been no studies of trends in the incidence of OA anywhere in the world."

Using an administrative database maintained by the provincial Ministry of Health, the researchers examined changes in the incidence rates of OA between 1996 to 1997 and 2003 to 2004. Two definitions of OA were used: definition 1 required at least one visit or hospitalization with a diagnostic code for OA, and definition 2 required at least two visits or one hospitalization with a code for OA.
 

Crude incidence rates of OA based on definition 1 rose from 10.5 to 12.2 per 1000 in men and from 13.9 to 17.4 per 1000 in women, according to the authors. Age-standardized rates in women increased from 14.7 to 16.7 per 1000 but changed little in men.

Based on definition 2, the incidence rates were approximately 45 per cent to 48 per cent lower than those based on definition 1. However, the trends were similar.

"These trends have important implications for public health and provision of health services to this very large group of patients," the researchers conclude.