OBJECTIVE: To determine the clinical features of psoriatic arthritis (PsA) in a multiethnic Oriental population and to study the effect of ethnicity on disease patterns.
METHODS: A retrospective study of 80 patients with PsA seen at either a rheumatology or dermatology referral center. Patients and case records were reviewed and data abstracted according to a standard protocol. Eighty consecutive patients with psoriasis without PsA seen at the dermatology center were recruited as controls.
RESULTS: Asymmetric polyarthritis developing in the 4th decade with an equal male to female ratio was the commonest pattern of arthritis among Chinese, Indians, and Malays. Clinically apparent lumbar spondylitis was significantly more common in Indians than Chinese (10/11 vs 11/20, respectively; p = 0.046), although the prevalence of lumbar spondylitis was similar in all ethnic groups. Eighty-nine percent of subjects required nonsteroidal antiinflammatory drugs and 51% required disease modifying antirheumatic drugs at some time for control of joint disease. PsA was significantly more common among Indians compared to the ethnic distribution of the Singapore population (p < 0.000001). Multiple logistic regression identified Indian ethnicity as a risk factor for the development of PsA (OR 2.39, 95% confidence interval 1.02 to 5.60).
CONCLUSION: The commonest pattern of PsA in all ethnic groups was asymmetric polyarthritis. Ethnicity affected the development and presentation of PsA in our series: Indians with psoriasis had double the risk of developing PsA compared to Chinese with psoriasis, and lumbar spondylitis when present in Chinese subjects was asymptomatic in 45%, being detectable only on radiological examination.
Nail psoriasis affects 20% to 30% of psoriasis patients and is an early predictor of psoriatic arthritis (PsA). We evaluated the prevalence, clinical characteristics, and impact on quality of life of patients with nail psoriasis. We conducted a multicenter retrospective cohort study of patients registered with The Malaysian Psoriasis Registry from January 1, 2007 to December 31, 2020. Of the 24,147 patients, 13,081 (54.2%) had nail psoriasis. Patients with nail psoriasis had later onset of psoriasis (34.0 ± 16.6 years vs 32.9 ± 17.6 years, P < .001) and longer disease duration (11.4 ± 10.5 years vs 8.5 ± 9.4 years, P < .01), with a man-to-woman ratio of 1.2:1. They were more likely to have a family history of psoriasis, cardiometabolic diseases, smoking history, higher body mass index, severe disease, PsA, face and scalp involvement, and higher mean Dermatology Life Quality Index scores (9.36 ± 6.84 vs 8.87 ± 6.60). Systemic treatment and biologics were more commonly prescribed in this cohort (25.0% vs 13.2%, P < .001). Overall, 54.2% of the Malaysian Psoriasis Registry patients had nail involvement. Nail psoriasis was associated with longer duration of psoriasis, older age of onset, male sex, and a family history of psoriasis. It proved to be an important predictor for PsA, severe psoriasis, face and scalp involvement, increased cardiometabolic risk, and a greater impairment of quality of life.