Comparable effects of exercise and analgesics for pain secondary to knee osteoarthritis: a meta-analysis of trials included in Cochrane systematic reviews.

AIM: Evidence of comparative effectiveness of different treatment approaches is important for clinical decision-making, yet absent for most recommended treatments of knee osteoarthritis pain. The objective of this study was to estimate the comparative effectiveness of exercise versus orally administered analgesics for pain in patients with knee osteoarthritis. METHODS: The Cochrane Database of systematic reviews was searched for meta-analyses of randomized controlled studies comparing exercise or analgesics with a control group (placebo or usual care) and with pain as an outcome. Individual study estimates were identified and effect sizes were calculated from group differences. We combined study-level effects on pain with a random effects meta-analysis and compared effect sizes between exercise trials and trials with analgesic interventions. RESULTS: We included six Cochrane reviews (four pharmacology, two exercise). From these, 54 trials were eligible (20 pharmacology, 34 exercise), with 9806 participants (5627 pharmacology, 4179 exercise). The pooled effect size of pharmacological pain interventions was 0.41 (95% CI: 0.23-0.59) and for exercise 0.46 standardized mean difference (95% CI: 0.34-0.59). There was no statistically significant difference between the two types of intervention (difference: 0.06 standardized mean difference [95% CI: -0.28-0.16; p = 0.61]). CONCLUSION: This meta-epidemiological study provides indirect evidence that for knee osteoarthritis pain, the effects from exercise and from oral analgesics are comparable. These results may support shared decision-making where a patient for some reason is unable to exercise or who consider exercise as unviable and analgesics as a more feasible choice. PROSPERO registration: CRD42013006924.

Assessing bias in osteoarthritis trials included in Cochrane reviews: protocol for a meta-epidemiological study.

INTRODUCTION: The validity of systematic reviews and meta-analysis depends on methodological quality and unbiased dissemination of trials. Our objective is to evaluate the association of estimates of treatment effects with different bias-related study characteristics in meta-analyses of interventions used for treating pain in osteoarthritis (OA). From the findings, we hope to consolidate guidance on interpreting OA trials in systematic reviews based on empirical evidence from Cochrane reviews. METHODS AND ANALYSIS: Only systematic reviews that compare experimental interventions with sham, placebo or no intervention control will be considered eligible. Bias will be assessed with the risk of bias tool, used according to the Cochrane Collaboration's recommendations. Furthermore, center status, trial size and funding will be assessed. The primary outcome (pain) will be abstracted from the first appearing forest plot for overall pain in the Cochrane review. Treatment effect sizes will be expressed as standardised mean differences (SMDs), where the difference in mean values available from the forest plots is divided by the pooled SD. To empirically assess the risk of bias in treatment benefits, we will perform stratified analyses of the trials from the included meta-analyses and assess the interaction between trial characteristics and treatment effect. A relevant study-level covariate is defined as one that decreases the between-study variance (τ(2), estimated as Tau-squared) as a consequence of inclusion in the mixed effects statistical model. ETHICS AND DISSEMINATION: Meta-analyses and randomised controlled trials provide the most reliable basis for treatment of patients with OA, but the actual impact of bias is unclear. This study will systematically examine the methodological quality in OA Cochrane reviews and explore the effect estimates behind possible bias. Since our study does not collect primary data, no formal ethical assessment and informed consent are required. TRIAL REGISTRATION NUMBER: PROSPERO (CRD42013006924).