The Epidemiology of Psoriatic Arthritis Over Five Decades: A Population-Based Study

Objective To determine the incidence of psoriatic arthritis (PsA) in a US population and describe trends in incidence and mortality over 5 decades. Methods The previously identified population-based cohort that included Olmsted County, Minnesota residents >= 18 years of age who fulfilled PsA criteria during 1970-1999 was extended to include patients with incident PsA during 2000-2017. Age- and sex-specific incidence rates and point prevalence, adjusted to the 2010 US White population, were reported. Results There were 164 incident cases of PsA in 2000-2017 (mean +/- SD age 46.4 +/- 12.0 years; 47% female). The overall age- and sex-adjusted annual incidence of PsA per 100,000 population was 8.5 (95% confidence interval [95% CI] 7.2-9.8) and was higher in men (9.3 [95% CI 7.4-11.3]) than women (7.7 [95% CI 5.9-9.4]) in 2000-2017. Overall incidence was highest in the 40-59 years age group. The incidence rate was relatively stable during 2000-2017, with no evidence of an overall increase or an increase in men only (but a modest increase of 3% per year in women), compared to 1970-1999 when a 4%-per-year increase in incidence was observed. Point prevalence was 181.8 per 100,000 population (95% CI 156.5-207.1) in 2015. The percentage of women among those with PsA increased from 39% in 1970-1999 and 41% in 2000-2009 to 54% in 2010-2017 (P = 0.08). Overall survival in PsA did not differ from the general population (standardized mortality ratio 0.85 [95% CI 0.61-1.15]). Conclusion The incidence of PsA in this predominantly White US population was stable in 2000-2017, in contrast to previous years. However, an increasing proportion of women with PsA was found in this study.