Environmental risk factors for psoriatic arthritis

A number of environmental exposures, including trauma, are associated with the onset of inflammatory arthritis in patients with psoriasis. Psoriatic arthritis is a type of inflammatory arthritis that affects five to seven per cent of the people suffering from psoriasis, a skin disorder characterised by red, swollen skin lesions covered with silvery white scales. Usually arthritis post-dates, often by several years, the onset of psoriasis. So for patients with psoriasis, it would be helpful to know what factors increase their risk of developing this condition. To investigate, researchers in the United Kingdom compared 98 patients who developed inflammatory arthritis within the past five years to a "control group" of 163 patients with psoriasis but no arthritis. A postal questionnaire was used to assess potential factors associated with the development of inflammatory arthritis. Exposures before the onset of arthritis that positively correlated with the condition included rubella vaccination (almost five per cent for psoriatic arthritis patients versus less than one per cent for controls); trauma requiring medical care (15 per cent versus eight per cent) and recurrent oral ulcers (25 per cent versus nine per cent). It was found that patients with psoriatic arthritis were more likely to have moved house than the controls (30 per cent versus 18 per cent, respectively). Psoriatic arthritis patients were also more likely than controls to have had a bone fracture that required hospital admission (50 per cent versus 9 per cent). The findings show that a number of environmental exposures contribute to the development of arthritis in patients with psoriasis. Further studies are needed to verify these observations and to examine potential biological mechanisms that underlie this disease.