Time Trends in Epidemiology and Characteristics of Psoriatic Arthritis Over 3 Decades: A Population-based Study

Objective. To determine time trends in incidence, prevalence, and clinical characteristics of psoriatic arthritis (PsA) over it 30-year period. Methods. We identified a population-based incidence cohort of subjects aged 18 years or over who fulfilled ClASsifcation of Psoriatic ARthritis (CASPAR) criteria for PsA between January 1, 1970, and December 31, 1999, in Olmsted County, Minnesota, USA. PsA incidence date wits defined as the diagnosis date of those who fulfilled CASPAR criteria. Age- and sex-specific incidence rates were estimated and age- and sex-adjusted to the 2000 US White population. Results. The PsA incidence cohort comprised 147 adult subjects with a mean age of 42.7 years, and 61%; were men. The overall age- and sex-adjusted annual incidence of PsA per 100,000 wits 7.2 [95% confidence interval (CI) 6.0, 8.4] with a higher incidence in men (9.1, 9570 CI 7.1, 11.0) than women (5.4, 95%, CI 4.0, 6.9). The age- and sex-adjusted incidence of PsA per 100,000 increased front 3.6 (95% CI 2.0, 5.2) between 1970 and 1979 to 9.8 (95%, CI 7.7, 11.9) between 1990 and 2000 (p for trend < 0.001). The point prevalence per 100,000 was 158 (95%: CI 1322, 185) in 2000, with a higher prevalence in men (193, 95%; CI 150, 237) than women (127, 95% CI 94, 160). At incidence, most PsA subjects had oligoarticular involvement (49%) with enthesopathy (29%). Conclusion. The incidence of PsA has been rising over 30 years in men and women. Reasons for the increase are unknown, but may be related to a true change in incidence or greater physician awareness of the diagnosis. (First Release Jan 15 2009; J Rheumatol 2009;36:361-7; doi:10.3899/jrheum.080691)