The International Classification of Functioning, Disability and Health (ICF) is a framework and classification of health that describes health along 4 components: body functions, body structures, activities and participation, and contextual factors. This study examined the content of instruments that constitute the Outcome Measures in Rheumatology (OMERACT) core set of outcome measures for antineutrophil cytoplasmic antibody-associated vasculitis (AAV) by "mapping" them to the ICF.
The content of the instruments included in the AAV core set were linked to the ICF by 2 independent investigators according to previously established ICF linkage rules.
The AAV core set includes 3 measures of disease activity (3 versions of the Birmingham Vasculitis Activity Score), 1 damage measure (Vasculitis Damage Index), 1 patient-reported outcome (Short Form 36 health survey), and death. Linking these instruments to the ICF revealed comprehensive coverage of the ICF components body functions and body structures, limited coverage of the ICF component activities and participation, and complete absence of coverage of contextual factors.
ICF was found to be useful for thematic characterization of a heterogeneous group of outcome measures for AAV, i.e., a group of complex medical conditions. Linking of the instruments selected for the OMERACT AAV core set of outcome measures to the ICF classification revealed limitations in the representation of constructs related to life impact of AAV, represented by the ICF components activities and participation and contextual factors. Further research and methods development are needed to better incorporate important aspects of functioning and health relevant to patients into clinical trials of AAV.