Cross-sectional study assessing family members of psoriatic arthritis patients affected by the same disease: differences between Caucasian, South Asian and Afro-Caribbean populations living in the same geographic region.

ABSTRACT

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 Caucasians (n = 88, 58.3%) than in South Asians (n = 28, 18.5%; P < 0.001) or African/Afro-Caribbean (n = 11, 7.3%; P < 0.002) individuals. Caucasians more commonly had relatives affected by the disease (49/78, 62.8%) than in South Asians (16/33, 48.4%; P < 0.034). CONCLUSIONS: Psoriatic arthritis was more common in Caucasian than in South Asian patients. The relatives of Caucasian patients were also more likely to have PsA compared with South Asian patients. Among South Asian patients, the relatives of Pakistani patients were significantly more likely to have PsA compared with other South Asian populations. Patients with a relative with PsA were three times more likely to develop PsA, with an increased likelihood for Pakistani individuals (by a factor of 5.29) compared with other South Asians (2.88) and Caucasians (4.32).