Measuring functioning in patients with hand osteoarthritis--content comparison of questionnaires based on the International Classification of Functioning, Disability and Health (ICF).

Objective: When selecting a questionnaire, researchers and clinicians need to know whether or not a questionnaire covers the relevant outcomes. The aim of this study was to analyse and compare the content of questionnaires that have been used to assess functioning in patients with hand osteoarthritis (OA) based on the International Classification of Functioning, Disability and Health (ICF).

Methods: Questionnaires were identified in a structured literature search. All concepts included in the items of the questionnaires were linked to the ICF categories according to the 10 established linking rules by two health professionals. The degree of agreement between the two health professionals was determined by means of kappa statistic. On the basis of the linking, the content of the instruments was compared. For each concept, it was examined whether functioning is measured on the level of activity or participation or both activity and participation. Indicators for content density, content diversity and the percentage of linked ICF categories addressing participation were calculated.

Results: Health Assessment Questionnaire, AUSCAN, Cochin scale, FIHOA, SACRAH and AIMS2-SF were analysed. The result of the kappa statistic for agreement between the two investigators was 0.74. 163 concepts were identified in the 113 items of all instruments, which were then linked to seven ICF categories of the component body functions, 45 categories of the component activities and participation and six categories of the component environmental factors. AUSCAN and SACRAH had the lowest and AIMS2-SF showed the highest diversity ratio and the highest percentage of linked ICF categories that addressed participation.

Conclusions: When selecting instruments for comprehensive measurements of functioning in hand OA, researchers and clinicians are advised to include both one instrument with a low diversity ratio (for disease-specific aspects) and another instrument with a high diversity ratio (for broader aspects of functioning including some aspects of participation).