Cross‐sectional study assessing family members of psoriatic arthritis patients affected by the same disease: differences between C aucasian, S outh A sian and A fro‐ C aribbean populations living in the same geographic region

Aim To determine the likelihood of an individual developing psoriatic arthritis ( PsA ) if they have a relative diagnosed with this disease, and to compare rates among different ethnic groups living in the same geographic region. Method Family histories of patients with PsA were assessed using a semi‐structured questionnaire. Results Data on family members of patients with SpA were collected for 151 patients (46.6%) of the total cohort of 324. A total of 146 patients in the SpA cohort had PsA (45%) and 88 of these patients (60.2%) also had relatives with PsA . Psoriatic arthritis was seen more commonly in C aucasians ( n  =   88, 58.3%) than in S outh A sians ( n  =   28, 18.5%; P  <   0.001) or A frican/ A fro‐ C aribbean ( n  =   11, 7.3%; P  <   0.002) individuals. Caucasians more commonly had relatives affected by the disease (49/78, 62.8%) than in S outh A sians (16/33, 48.4%; P  <   0.034). Conclusions Psoriatic arthritis was more common in C aucasian than in S outh A sian patients. The relatives of C aucasian patients were also more likely to have PsA compared with S outh A sian patients. Among S outh A sian patients, the relatives of P akistani patients were significantly more likely to have PsA compared with other S outh A sian populations. Patients with a relative with PsA were three times more likely to develop PsA , with an increased likelihood for P akistani individuals (by a factor of 5.29) compared with other S outh A sians (2.88) and C aucasians (4.32).