Towards an ICF Core Set for chronic musculoskeletal conditions:: commonalities across ICF Core Sets for osteoarthritis, rheumatoid arthritis, osteoporosis, low back pain and chronic widespread pain

The objective of the study was to identify commonalities among the International Classification of Functioning, Disability and Health (ICF) Core Sets of osteoarthritis (OA), osteoporosis (OP), low back pain (LBP), rheumatoid arthritis (RA) and chronic widespread pain (CWP). The aim is to identify relevant categories for the development of a tentative ICF Core Set for musculoskeletal and pain conditions. The ICF categories common to the five musculoskeletal and pain conditions in the Brief and Comprehensive ICF Core Sets were identified in three steps. In a first step, the commonalities across the Brief and Comprehensive ICF Core Sets for these conditions were examined. In a second and third step, we analysed the increase in commonalities when iteratively excluding one or two of the five conditions. In the first step, 29 common categories out of the total number of 120 categories were identified across the Comprehensive ICF Core Sets of all musculoskeletal and pain conditions, primarily in the component activities and participation. In the second and third step, we found that the exclusion of CWP across the Comprehensive ICF Core Sets increased the commonalities of the remaining four musculoskeletal conditions in a maximum of ten additional categories. The Brief ICF Core Sets of all musculoskeletal and pain conditions contain four common categories out of a total number of 62 categories. The iterative exclusion of a singular condition did not significantly increase the commonalities in the remaining. Based on our analysis, it seems possible to develop a tentative Comprehensive ICF Core Set across a number of musculoskeletal conditions including LBP, OA, OP and RA. However, the profile of functioning in people with CWP differs considerably and should not be further considered for a common ICF Core Set.