Objectives To compare functional limitations in patients with chronic gout and matched patients with rheumatoid arthritis (RA) as measured with the HAQ-DI and PF-10.
Methods Consecutive patients with crystal deposition proven gout (n=102) or with RA (n=619) visiting the outpatient rheumatology clinic of the hospital in Enschede, the Netherlands completed the HAQ-DI and PF-10. Gout patients were matched to patients with RA on sex, age (± 5 years) and disease duration (±5 years). Ninety-three patients with gout could be successfully matched to 93 patients with RA.
The HAQ-DI contains 20 items measuring physical disabilities over the past week in eight categories of daily living. Items are scored on a 4-point rating scale from 0 (without any difficulty) to 3 (unable to do). A total score is calculated by averaging the highest score in each category if at least six categories are completed. The PF-10 is the physical functioning scale of the multidimensional SF-36v2. It measures current limitations in a variety of physical activities using 10 items. Items are scored from 1 (yes, limited a lot) to 3 (no, not limited at all). Scores on the PF-10 items are summed and linearly transformed to range between 0 and 100, with higher scores indicating better functioning.
Results In both disease groups mean age was 59 (± 12) years, mean disease duration was 7 (±9) years and 86% of patients were male. Median PF-10 scores did not significantly differ between patients with gout or with RA and ceiling effects (no limitations) were similar (6.7% versus 6.5%) (see table). However, patients with RA had significantly worse HAQ-DI total scores than patients with gout, and ceiling effects were significantly lower in RA than in gout. Analysis of HAQ-DI category scores showed that gout patients had less limitations in activities that involve the upper extremities such as Dressing, Eating, Hygiene and Grip than RA patients, while scores for activities mostly involving the lower extremities were similar.
Conclusions Gout patients have less functional limitations than RA patients according to HAQ-DI total scores, while according to PF-10 scores gout patients and RA patients do not significantly differ in functional limitations. HAQ-DI seems to underestimate the functional limitations of gout patients compared to RA patients because of the inclusion of activities involving upper extremities, which may be less relevant for patients with gout. On the other hand PF-10 seems to underestimate the functional limitation of patients with RA because of the emphasis on activities involving lower extremities.
Disclosure of Interest None Declared
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