Objectives: To systematically identify and compare the concepts contained in outcome measures of clinical trials on low back pain, chronic widespread pain, osteoarthritis, osteoporosis and rheumatoid arthritis using the International Classification of Functioning, Disability and Health (ICF) as a reference.
Methods: Randomized controlled trials carried out between 1991 and 2000 were identified using MEDLINE and selected according predefined criteria. The outcome measures were extracted and the concepts contained in the outcome measures were linked to the ICF.
Results: One hundred and twenty-nine trials on low back pain, 42 trials on chronic widespread pain, 176 trials on osteoarthritis, 107 trials on osteoporosis and 382 trials on rheumatoid arthritis were included. Fifty-nine different health status questionnaires were extracted in low back pain, 29 in chronic widespread pain, 29 in osteoarthritis, 3 in osteoporosis and 48 in rheumatoid arthritis. Across conditions at least 77% (range 77-88%) of the extracted concepts could be linked to the ICF. In low back pain, chronic widespread pain and osteoarthritis the most used ICF-categories were sensation of pain (b280), in osteoporosis structure of trunk (s760) and in rheumatoid arthritis additional musculoskeletal structures related to movement (s770). The most used category across conditions was sensation of pain (b280) except for osteoporosis.
Conclusion: The ICF provides a useful reference to identify and quantify the concepts contained in outcome assessment used in clinical trials.