The Outcome Measures in Rheumatology workgroup (OMERACT), together with the Osteoarthritis Research Society International (OARSI) developed the OMERACT-OARSI responder criteria. These criteria are used to determine if a patient with osteoarthritis (OA) 'responds' to therapy, meaning experiences a clinically relevant effect of therapy. Recently, more clinical OA trials report on this outcome and most OA trials have data to calculate the number of responders according to these criteria. A systematic review and meta-analysis were performed on the response to exercise therapy, compared to no or minimal intervention in patients with hip OA using the OMERACT-OARSI responder criteria. The literature was searched for relevant randomized trials. If a trial fit the inclusion criteria, but number of responders was not reported, the first author was contacted. This way the numbers of responders of 14 trials were collected and a meta-analysis on short term (directly after treatment, 12 trials n = 1178) and long term (6-8 months after treatment, six trials n = 519) outcomes was performed. At short term, the risk difference (RD) was 0.14 (95% confidence interval (CI) 0.06-0.22) and number needed to treat (NNT) 7.1 (95% CI 4.5-17); at long term RD was 0.14 (95% CI 0.07-0.20) and NNT 7.1 (95% CI 5.0-14.3). Quality of evidence was moderate for the short term and high for the long term. In conclusion, 14% more hip OA patients responded to exercise therapy than to no therapy.
Keywords: exercise therapy; hip osteoarthritis; meta-analysis; responders.