Assessment of physical activity in daily life in patients with musculoskeletal pain.

Patients with musculoskeletal pain often report limitations in daily functioning due to pain. Recently, the World Health Organisation (WHO) recommended in their International Classification of Functioning, Disability and Health (ICF) to accentuate patients remaining possibilities in functioning instead of focussing on restrictions. In patients with musculoskeletal pain, this would imply that a person's "daily activity level" rather than his/her "disability level" has to be focussed upon. At this moment, broad consensus about how to measure physical activity in daily life in patients with pain has not been established. The objectives of this study were twofold, firstly to identify instruments assessing the level of physical activity in daily life in patients with musculoskeletal pain and secondly to review psychometric properties of the instruments identified. In all, 42 articles derived from the literature on musculoskeletal pain were included in the review. Thirty four assessment instruments for physical activity were identified; fourteen questionnaires, ten diaries and ten instruments based on movement registration. Only, 10 out of these 34 instruments contained full or partial information regarding pain specific psychometric properties. At this moment, for quantitative assessment of physical activity, movement registration seems to be favoured based on its higher degree of objectivity in comparison with self report. Taken together more research is needed to evaluate psychometric properties of instruments measuring physical activity in musculoskeletal pain.