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Using bivariate meta-analysis and meta-regression to investigate the effects of exercise on pain and disability in osteoarthritis

Date and Location




Sunday 22 September 2013 - 10:30 - 12:00


Presenting author and contact person

Presenting author

Olalekan Uthman

Contact person

Danielle van der ...
Abstract text
Background: Previous reviews have documented that exercise interventions are more effective than no exercise control for osteoarthritis (OA) however effect estimates vary widely. Objectives: To estimate effectiveness of exercise interventions and explore trial-level characteristics that may be associated with effect size estimates of exercise for OA. Methods: Pain and functional limitations are both key outcomes in OA. Bivariate random effects meta-analysis was used to simultaneously synthesize effects on pain and function, taking the correlation between the two outcomes into account. We calculated 95% prediction intervals which incorporate between-study variability. A series of unadjusted bivariate meta-regression analyses was carried out to investigate the impact of trial-level characteristics on treatment effect size estimates. Results: A total of 43 trials involving 4466 patients met the inclusion criteria. The results of the bivariate meta-analysis showed that exercise interventions significantly reduced pain (Δ = -1.35 cm; 95% CI -1.75 to -0.95cm, 10 cm visual analogue scale) and improved function (1.03 units; 95% CI -1.60 to -0.80 units, WOMAC disability scale from 0 to 10). There was statistically significant strong correlation (0.740, p<0.001) between pain relief and improvement in function. The prediction intervals suggest that exercise interventions applied at population level may not always be beneficial in all settings, about 15% future trials are likely to show exercise not to be effective for pain and function. Exercise tended to be more effective among younger adults; in hospital-based settings, and when supervised and standardized. Trials with low risk of bias showed less promising results. Conclusions: This review provides insight into some of the sources of variability in effect estimates of exercise interventions for OA. In this bivariate meta-analysis, effect estimates for pain and function were pooled simultaneously in a single analysis in order to reduce reporting bias due to outcome measures ‘borrowing strength’ from each other.