To validate the International Classification of Functioning, Disability and Health (ICF) Comprehensive Core Set for Rheumatoid Arthritis (RA) from the patient perspective.
Patients with RA were interviewed about their problems in daily functioning. Interviews were tape recorded and transcribed verbatim. Interview texts were divided into meaning units. The concepts contained in these meaning units were linked to the ICF according to 10 established linking rules. Of the transcribed data, 15% were analyzed and linked by a second health professional. The degree of agreement was calculated using the kappa statistic.
Twenty-one patients were interviewed. Two hundred twenty different concepts contained in 367 meaning units were identified in the qualitative analysis of the interviews and linked to 109 second-level ICF categories. Of the 76 second-level categories from the ICF RA Core Set, 63 (83%) were also found in the interviews. Twenty-five second-level categories, which are not part of the current ICF RA Core Set, were identified in the interviews. The result of the kappa statistic for agreement was 0.62 (95% boot-strapped confidence interval 0.59-0.66).
The validity of the ICF RA Core Set was supported by the perspective of individual patients. However, some additional issues raised in this study but not covered in the current ICF RA Core Set need to be investigated.