Risk factors associated with having psoriatic arthritis in patients with cutaneous psoriasis.

The aim of this study was to determine if the following characteristics were associated with the presence of psoriatic arthritis in a sample of psoriasis patients: race, family history of psoriasis and psoriatic arthritis, age of onset of psoriasis, smoking, alcohol consumption and the maximum body surface area (BSA) affected by psoriasis. This was a case-control study involving 400 psoriasis patients who attended the Psoriasis and Photo-medicine clinic in the National Skin Center of Singapore over a 1-year period. Cases were psoriasis patients with psoriatic arthritis while controls were psoriasis patients without psoriatic arthritis. The diagnosis of psoriatic arthritis was made by rheumatologists and participants completed a self-administered standardized questionnaire. The maximum BSA involved was determined from the case notes. Psoriatic arthritis was not significantly associated with sex, race, age of onset of psoriasis, a family history of psoriasis, smoking and alcohol consumption but was significantly associated with a family history of psoriatic arthritis (P < 0.001) and the maximum body surface involved (P = 0.05). Using multivariate analysis to control for variables, the presence of psoriatic arthritis was significantly associated with a family history of psoriatic arthritis (odds ratio [OR] = 20.5; 95% confidence interval [CI] = 2.49-169.10) and the maximum BSA involved (OR = 2.52; 95% CI = 1.33-4.75). Indian psoriatic patients were more likely to have psoriatic arthritis compared to the other races. A family history of psoriatic arthritis and a greater maximum body surface involved may be associated with having psoriatic arthritis in this study population of psoriasis patients.

Solar urticaria in Singapore: an uncommon photodermatosis seen in a tertiary dermatology center over a 10-year period.

BACKGROUND: Solar urticaria is an uncommon photodermatosis, characterized by the appearance of pruritic wheals after sun exposure. In this study, we examine the photobiological characteristics of solar urticaria in the heterogeneous group of Singaporean patients. METHODS: The photobiological features of all patients treated for solar urticaria at a tertiary dermatology center in Singapore over a 10-year period were retrospectively examined. RESULTS: A total of 19 patients were diagnosed to have solar urticaria from 1993 to 2002. The mean age at diagnosis was 26 years, with a racial distribution of 17 (90%) Chinese, one (5%) Malay, and one (5%) Indian. Fifteen (79%) patients were males and four (21%) were females. The face/neck (47%) and arms/forearms (58%) were most often affected. Six (32%) patients had a history of atopy and two (11%) had dermographism. Fifteen (79%) patients had Fitzpatrick's skin type IV, three (16%) had skin type III and one (5%) patient had skin type V. The mean exposure time to wheal formation was 23 min. The action spectra of solar urticaria were visible light for 12 (63%) patients, ultraviolet (UV) A for one (5%), visible light and UVA for five (27%), and natural sunlight for one (5%) patient. All patients reported partial improvement with a combination of antihistamines and sunscreens as the main modality of treatment. CONCLUSIONS: Our data suggest that solar urticaria is an uncommon photodermatosis and a rare form of urticaria. Wheals were mostly elicited by visible light and/or UVA. A combination of antihistamines and sunscreens provided a useful form of therapy for patients with solar urticaria.