Responsiveness of the International Classification of Functioning, Disability and Health (ICF) Core Set for rheumatoid arthritis

Background: The comprehensive International Classification of
Functioning, Disability and Health (ICF) Core Set for rheumatoid
arthritis (RA) is a selection of 96 categories from the ICF,
representing relevant aspects in the functioning of patients with
RA. Objectives: To study the responsiveness of the ICF Core Set for
RA in rheumatological practice. Methods: A total of 46 patients
with RA (72% women, mean (SD) age 53.6 (12.6) years, disease
duration 6.3 (8.0) years) were interviewed at baseline and again
after 6 months treatment with a disease-modifying antirheumatic
drug (DMARD), applying the ICF Core Set for RA with qualifiers for
problems on a modified three-point scale (no problem,
mild/moderate, severe/complete). Patient-reported outcomes included
Modified Health Assessment Questionnaire (MHAQ) and Short-Form 36
(SF-36) health survey, and disease activity was calculated.
Responsiveness was measured as change in qualifiers in ICF
categories, and was also compared with change in patient-reported
outcomes. Results: After 6 months of DMARD treatment, improvement
by at least one qualifier was seen in 20% of patients (averaged
across all ICF categories), 71% experienced no change and 9%
experienced worsening symptoms. Findings were similar across the
different aspects of functioning. Mainly moderate effect sizes were
seen for 6-month changes in the ICF Core Set for RA, especially in
patients with improved health status, with similar effect size for
disease activity. The components in the ICF Core Set for RA were
only weakly associated with patient-reported outcomes and disease
activity. Conclusions: The ICF Core Set for RA demonstrated
moderate responsiveness in this real-life setting of patients where
minor changes occurred during treatment with DMARDs.