Outcome measurement in osteoarthritis clinical trials: the case for standardisation.

Outcome measures for clinical trials to be valid and reliable should also be responsive to change. There are currently no standardised methods of measuring the outcome in osteoarthritis clinical trials. A review of 63 trials of nonsteroidal anti-inflammatory drugs revealed a large degree of variability in the items, instruments and scales employed. The implications of this variability are discussed and methods proposed for rationalising outcome measurement in this area of clinical research.