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.