There is no consensus on the best approach for measuring physical activity in patients with osteoarthritis (OA) of the hip or knee. The aims of this study were (1) to identify all physical activity measures that have been validated in patients with OA of the hip or knee and to systematically review their measurement properties, and (2) to give recommendations on which instrument is most suitable for what purpose.
A search was performed in PubMed, Embase, and Sportdiscus (complete databases until November 10, 2010). Three reviewers independently evaluated the quality of the included studies, using the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist. Subsequently, the reviewers independently evaluated the quality of the included physical activity instruments, using the recently developed QAPAQ checklist for appraising the qualitative attributes and measurement properties of physical activity questionnaires.
Nine studies were included, in which 12 measurement instruments were evaluated: five single-item rating scales, six multi-item questionnaires, and one pedometer. In general, the methodological quality of the studies was poor to moderate. Only the Lower-Extremity Activity Scale (LEAS) and the pedometer received positive ratings for content validity. The LEAS and Baecke questionnaire received positive ratings for reliability. The University of California at Los Angeles (UCLA), the Tegner score, and the LEAS received positive ratings for construct validity. The Daily Activity Questionnaire (DAQ) received a positive rating for criterion validity. Responsiveness was not evaluated for any of the included instruments.
For monitoring physical activity levels of populations the UCLA or LEAS seem most useful. For studies measuring physical activity as a risk factor for developing OA or as a protective factor against functional decline there is not enough evidence for any instrument to conclude that it has adequate measurement properties. For follow-up studies on wear in joint replacement patients we recommend to use accelerometers. However, more validation studies of adequate quality are needed for all included instruments.