Last Updated: 2008-05-14 12:07:04 -0400 (Reuters Health)

NEW YORK (Reuters Health) – A number of environmental exposures, including trauma, are associated with the onset of inflammatory arthritis in patients with psoriasis, findings published in the May issue of the Annals of the Rheumatic Diseases indicate.

"Psoriatic arthritis (PsA) can be considered as a ‘disease within a disease’, i.e., the occurrence of PsA can be considered as the appearance of inflammatory arthritis on a background of pre-existing or future development of psoriasis," Dr. Ian N. Bruce, of the University of Manchester, UK, and colleagues write.

"Usually arthritis post-dates, often by several years, the onset of psoriasis," they note. "It is therefore relevant to consider what factors, in individuals with psoriasis, increase their risk of developing arthritis."

To investigate, the researchers compared 98 patients with psoriasis and an onset of inflammatory arthritis within the past 5 years to a control group of 163 patients who had 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 showed a positive association included rubella vaccination (4.6% for cases versus 0.7% for controls; odds ratio = 12.4), trauma requiring medical care (14.9% versus 7.9%; OR = 2.53), and recurrent oral ulcers (25.3% versus 8.9%; OR = 4.2).

Cases were more likely to have moved house (30.3%) than were controls (18.2%; OR = 2.29). Cases were also more likely than controls to have had a bone fracture that required hospital admission (50% versus 9%, respectively; p = 0.04).

"Replication of our findings, ideally in new onset cases, is required especially for those exposures not previously reported," Dr. Bruce and colleagues note. "Further understanding of how such triggers contribute to the development of psoriatic arthritis may also help elucidate key pathomechanisms of this disease."

Ann Rheum Dis 2008;67:672-676.

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