Kerschbaumer A, et al. – In this study, the specialists examined the effects of structural damage on functional disability in psoriatic arthritis (PsA). The evaluation suggested that structural damage, mainly joint space narrowing (JSN), possess important implications for physical function, in patients with PsA. Moreover, functional outcomes had an irreversible component that was strongly associated with the extent of joint destruction.

Methods

• The specialists reviewed 363 patients enrolled in the GO–REVEAL study.
• Modified Sharp/van der Heijde Scores (mSvdHS) were obtained from X–rays performed at baseline, after 24, 52 and 104 weeks.
• They applied longitudinal analyses and explored the effect of total mSvdHS (and its subscores, joint space narrowing (JSN) and erosions (ERO)) on functional status (measured by the Health Assessment Questionnaire) in all patients and in those attaining remission (n=117).
• Moreover, they determined whether structural damage reduces the responsiveness of functional limitations to treatment in a subgroup of responders who had functional impairment at baseline (n=67).
• Internal and external validation analyses were conducted.

Results

• The effect of damage on function was seen in the disease activity–adjusted models using total mSvdHS (p=0.005), JSN (p=0.019) and ERO (p=0.001) as well as in the remission analyses for mSvdHS (p=0.029) and JSN (p=0.010), respectively. 
• Functional responsiveness was limited by increasing total mSvdHS (p=0.010), JSN (p=0.002) and ERO (p=0.040). 
• With other functional outcomes and in an independent clinical cohort, the obtained results were validated.