(C-051) Global Assessment of the Diagnosed Prevalence of Psoriatic Arthritis

Background: Psoriatic arthritis (PsA) is a chronic, immune-mediated inflammatory disease that affects the musculoskeletal system and skin. The heterogeneity of the disease, lack of definitive diagnostic test and methodological differences in past epidemiological studies have contributed to the wide variations in prevalence estimates of PsA in the literature.

Objectives: To estimate the global, regional and country-specific 12-month prevalence of diagnosed PsA.

Methods: A literature search was conducted to identify population-based studies reporting the diagnosed prevalence of PsA, including those reporting PsA only or those with PsA and comorbid psoriasis (PsO). Three databases (MEDLINE, Web of Science Core Collection, SciELO) were searched for articles published between 2013 and 2023 without language restrictions. Diagnosed prevalent cases of PsA were defined as cases if diagnosed by a physician, diagnosed per the Classification Criteria for Psoriatic Arthritis or identified using the International Classification of Diseases diagnosis codes. For all countries assessed, prevalent cases were calculated by multiplying the annualized projected age- and sex-specific diagnosed prevalence with the corresponding age- and sex-specific population projections from the United Nations World Population Prospects (2019). In the absence of country-specific PsA estimates, proxy countries were selected for extrapolation based on similarities in race/ethnicity, geographic proximity and gross domestic product per capita. A 10-year projection period of the diagnosed prevalence of PsA was also estimated.

Results: Out of the 8,065 publications identified, 48 met the inclusion criteria. The global estimate of diagnosed PsA, spanning 71 geographies in total and across all ages, was 0.09% in 2024. Estimates ranged from 0.03% in China and 0.04% in Japan to 0.18% in the US and 0.27% for Europe (including France, Germany, Italy, Spain, UK). Among diagnosed prevalent cases of PsA globally, more patients were diagnosed with PsA and comorbid PsO (0.07%) than with PsA alone (0.02%). PsA was found to be more common in adults than in children; diagnosed prevalence ranged from 0.01% to 0.49% in adults and from 0.001% to 0.02% in children, across all included countries. Global estimates increased slightly over the 10-year projection period (from 0.09% in 2024 to 0.10% in 2033) with variations observed across regions.

Conclusions: The 2024 global diagnosed prevalence estimate of PsA was 0.09%, with higher prevalence in the US and Europe versus China and Japan. PsA was less common in children than in adults. The slight increase in global prevalence over time, especially among patients with PsA and comorbid PsO, can be partially attributed to changes in age and sex compositions over time.