SAT0404 INCIDENCE OF PSORIATIC ARTHRITIS FROM 2000-2017: A POPULATION-BASED STUDY

Abstract

Background:Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease with an estimated prevalence of 0.05% to 0.25% in the population and 6% to 41% in psoriasis patients. There is disparity in the reported incidence patterns in the general population in more recent years, with increasing incidence seen in Denmark, but relatively stable rates seen in Canada. However, no studies in the US have looked at the recent incidence patterns, and it would be important to see how newer therapies for psoriasis have impacted the incidence of PsA. Variability in the estimates of incidence and prevalence across different studies has been attributed to differences in case ascertainment and most studies have used ICD codes to identify PsA patients.Objectives:To determine the annual incidence of PsA (2000-17) and compare it to incidence of PsA in previous years (1970-1999)1in the Olmsted County, Minnesota, USA population.Methods:A retrospective, population-based cohort of PsA patients ≥18 years of age from Olmsted County, MN meeting ClASsification of Psoriatic ARthritis (CASPAR) criteria for PsA (2000-17) was identified from the Rochester Epidemiology Project (REP). REP ensures virtually complete ascertainment and follow-up of all clinically diagnosed cases of PsA in a geographically-defined area. The date of fulfillment of CASPAR criteria was taken as the PsA incidence date. Age- and sex-specific incidence rates, adjusted to 2010 US white population, were reported. Our previously reported cohort from REP (1970-1999)1also used the same CASPAR criteria, and trends from the current study were compared to the previous years.Results:There were 170 incident cases of PsA, with a mean age of 46.7 (SD=12.3) years and 47% females from 2000-17. The overall age and sex adjusted annual incidence of PsA per 100,000 population was 8.8 (95% CI 7.5-10.1), and higher in males (9.7, 95% CI 7.7-11.7) than females (8.0, 95% CI 6.2-9.8). Overall incidence was highest in the age range 40-59 years (Table 1). The incidence rate was relatively stable in the recent years 2000-2017 compared to 1970-19991where a rise in incidence was observed (3.6 to 9.8 per 100,000 persons from 1970-79 to 1990-99, p<0.001) (Figure 1).Table 1.Annual incidence rate, IR (per 100,000) of psoriatic arthritis by age and sex between 2000-17 in Olmsted County, MN.MaleFemaleTotalAge Group, yrsNIRNIRNRate18-2994.141.6132.830-392413.4147.33810.240-492413.92614.05014.050-592113.52816.24914.960-6976.987.1157.070-7935.000.032.280+26.000.022.2Total (95% CI)909.7 (7.7-11.7)†808.0 (6.2-9.8)†1708.8 (7.5-10.1)††† Age-adjusted to the 2010 US White population. †† Age- and sex-adjusted to the 2010 US White populationConclusion:In the Olmsted County population, the increasing PsA incidence seen in previous years 1970-19991seems to have leveled off after 2000. This is in contrast to increasing incidence in recent years reported from Denmark, Taiwan and Israel. However, similar to our study, incidence rates for PsA from 2008-2015 were reported to be stable in Canada.