Racial and ethnic determinants of psoriatic arthritis phenotypes and disease activity

Objective Individuals of racially and ethnically diverse backgrounds are underrepresented in PsA research/clinical trials, despite evidence that their disease presentation, severity and course may be distinct. Here we aim to describe how race, ethnicity and other socioeconomic factors inform disease characteristics in PsA.Methods A total of 817 consecutive patients with PsA from a large, diverse metropolitan area were enrolled in an observational, longitudinal registry. Demographics, medical history, medication use and psoriatic disease phenotype and activity were all recorded and analysed.Results The population was 77.4% non-Hispanic White, 2.2% Black, 7.1% Asian and 9.9% identified as other races or multiracial, and 11.8% identified as Hispanic. Hispanic and non-white individuals had higher tender joint counts (P = 0.033), with similar swollen joint counts (P = 0.308) and medication use (P = 0.171). They also had high rates of radiographic axial disease. Hispanic individuals were significantly more likely to have higher tender joint counts (P = 0.029), higher RAPID3 (Routine Assessment of Patient Index Data 3) scores (P = 0.004) and moderate-severe psoriasis (P = 0.010) compared with non-Hispanic White individuals.Conclusion In this diverse cohort, 22.6% of patients identified as underrepresented racial and/or ethnic groups, mostly Asian or Hispanic. Despite similar swollen joint counts and medication use, non-white individuals have higher tender joint counts compared with White individuals. Phenotypically, they also were more likely to have radiographic axial involvement. These findings may reflect differences in PsA presentation, experience and outcomes in individuals of various racial and ethnic groups, which need to be taken into consideration in clinical care and research design.