We read with interest the report by Ravaud et al.¹ This largest ever study of exercise in osteoarthritis (OA) (2957 people followed up for 24 weeks) examined the effect of patient self assessment and the adjunct of a booklet and videotape to encourage unsupervised exercise. They found significant reductions in pain and disability in all groups including controls, but no between-group differences, thus concluding a “true negative” result.

There is convincing evidence that exercise reduces pain and disability from knee and hip OA.² The authors suggest that small numbers and lack of attention control in previous studies and the unsupervised nature of their own programme may explain this discrepancy. Yet one UK study not cited by the authors recruited 786 subjects with knee pain (47% with radiographic OA) from three general practices and employed a minimally supervised exercise programme with attention control, demonstrating a clear benefit over 2 years.³

Several caveats of the Ravaud study warrant emphasis:

• All patients received rofecoxib, with paracetamol as escape analgesia, decreasing baseline pain and reducing the maximum possible effect of exercise. This regimen is …