RESEARCH - Environmental risk factors for the development of psoriatic arthritis

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Published Online First: 6 September 2007. doi:10.1136/ard.2007.073932

ls of the Rheumatic Diseases 2008;67:672-676

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EXTENDED REPORTS

Environmental risk factors for the development of psoriatic arthritis:

results from a case–control study

E Pattison 1, B J on 2, C E M Griffiths 3, A J Silman 1, I N Bruce 1

1 arc Epidemiology Research Unit, School of Translational Medicine,

The University of Manchester, Manchester, UK

2 Department of Rheumatology, North Manchester General Hospital, Manchester, UK

3 Dermatology Centre, Hope Hospital, School of Translational Medicine,

The University of Manchester, Salford, Manchester, UK

Objective: To identify potential risk factors for the onset of

inflammatory arthritis (IA) in a large cohort of patients with

psoriatic arthritis (PsA) of recent onset.

Methods: We recruited cases with psoriasis and an onset of IA within

the past 5 years. Controls were patients who had psoriasis but no

arthritis. We assessed potential factors associated with the

development of IA using a detailed postal questionnaire. An unmatched

analysis adjusted for age and gender was performed. Exposure was

censored in the controls at a " dummy-date " assigned randomly in

proportion to the percentage of cases developing IA in any given year.

Results: We studied 98 cases and 163 controls. Exposures showing a

positive association before the onset of IA in patients with psoriasis

were: rubella vaccination (OR (95% CI) = 12.4 (1.2 to 122)), injury

sufficient to require a medical consultation (2.53 (1.1 to 6.0)),

recurrent oral ulcers (4.2 (2.0 to 9.0)) and moving house (2.3 (1.2 to

4.4)). Cases were also more likely to have experienced a fractured

bone requiring hospital admission (50% vs 9%, p = 0.040).

Conclusions: We found a number of environmental exposures associated

with the onset of IA in subjects with psoriasis. The strongest

associations were with trauma thereby adding to the hypothesis of a

" deep Koebner phenomenon " in PsA. Our data also suggest that exposure

of the immune system to certain infection-related triggers may also be

of relevance. Further studies are needed to verify these observations

and to examine potential immunological mechanisms that underlie them.

http://ard.bmj.com/cgi/content/abstract/67/5/672?etoc

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