Objective The authors have previously reported on the relationship between activity and subsequent damage at the patient level for patients with psoriatic arthritis (PsA). The aim of this study was to identify key predictors of damage to individual joints in the hands and feet of patients with PsA, in particular those that capture previous activity.
Methods Data from patients followed prospectively at the University of Toronto PsA clinic between 1978 and 2006 were available for analysis. Logistic regression was used to relate the probability of a joint developing damage, within a specified time interval after the most recent clinic visit, to potential predictor variables. The predictor variables considered encompassed the history of disease activity of the joint and elsewhere, previous damage and the timing of clinical assessments.
Results 511 patients with no hand damage at clinic entry and 552 patients with no foot damage at clinic entry were included in the analysis of the hand and foot joints, respectively. The analysis of the hand and foot joints demonstrated that the activity (tenderness and/or swelling) history of the specific joint is associated with subsequent damage. For the joints of the feet, activity observations elsewhere in the same foot, and in particular the same toe, were also shown to be associated with subsequent damage.
Conclusions Both joint tenderness and swelling are important predictors of joint damage in PsA.
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Funding VC is supported by a Canadian Institutes of Health Research Clinical Research Initiative Fellowship, the Henry A Beatty Scholarship from the University Health Network and the Krembil Foundation. VTF and LC are supported by MRC funding U.1052.00.009. The University of Toronto Psoriatic Arthritis clinic is supported by the Krembil Foundation and by the Arthritis Society, Canada, through a national research initiative grant.
Competing interests None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the University Health Network Research Ethics Board.
Provenance and peer review Not commissioned; externally peer reviewed.