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Efficacy of strengthening or aerobic exercise on pain relief in people with knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials |
Tanaka R, Ozawa J, Kito N, Moriyama H |
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CRD summary This review concluded that muscle-strengthening exercises, with or without weight bearing, and aerobic exercise were effective for pain relief in people with knee osteoarthritis. Non-weight-bearing strengthening exercise was the most effective. There were method limitations in both the included trials and the meta-analyses, so the authors' conclusions appear to be over-optimistic. Authors' objectives To compare the efficacy of strengthening and aerobic exercises for pain relief in people with knee osteoarthritis. Searching MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL) and PEDro were searched to March 2013; search terms were reported and a strategy was available in an online appendix. No language restrictions were applied. Study selection Randomised controlled trials (RCTs) comparing an exercise intervention with no intervention or a psycho-educational intervention, for people with knee osteoarthritis, were included in the review. Exercise interventions could be non-weight-bearing strengthening exercise, weight-bearing strengthening exercise, or aerobic exercise. The primary outcome of interest was pain. Trials of preoperative or postoperative patients (having total knee arthroplasty) were excluded from the review. Trials of combined interventions, such as strengthening and aerobic exercise, were excluded. Trials of less than the median exercise frequency or longer than the median exercise duration, among the identified trials, were excluded. In the included trials, the average age of participants ranged from 55 to 70 years and most participants were female, where reported. The frequency of exercise was three times per week, and the duration was six to eight weeks. The various outcome assessment scales were; the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index, Osteoarthritis Screening Index (OASI), Arthritis Impact Measurement Scale (AIMS), a numeric rating scale, and a visual analogue scale. Two reviewers independently assessed studies for inclusion, with disagreements resolved by consensus. Assessment of study quality Trial quality was assessed using the PEDro scale. The authors did not state how many reviewers assessed quality. Data extraction Two reviewers extracted the data on pain; disagreements were resolved in consultation with a third reviewer. Pain data were standardised to the same scale, and the standardised mean difference was calculated, along with 95% confidence interval. Trials that did not give the mean and standard deviation, 95% confidence interval or the standard error of the mean, were excluded from the synthesis. Methods of synthesis A fixed-effect or random-effects meta-analysis was used to combine trial data, according to the level of statistical heterogeneity. Statistical heterogeneity was assessed using Χ² and quantified using Ι². Trials were grouped by the type of exercise (non-weight-bearing or weight-bearing strengthening exercise, or aerobic exercise) and subgroup analyses were performed. Publication bias was assessed using funnel plots and the Egger test. Effect sizes of 0.2 to 0.5 were considered small, 0.5 to 0.8 were considered medium, and greater than 0.8 were considered large. Results of the review Eight RCTs (466 participants; range 20 to 102) were included in the review, with eleven treatment groups. Four trials assessed non-weight-bearing muscle-strengthening exercise; concentric-eccentric, isometric, or isokinetic exercise without weight-bearing. One trial assessed weight-bearing muscle strengthening (leg press machine) with or without non-weight-bearing strengthening. Three trials assessed aerobic exercise; walking, Baduanjin or Tai Chi. The trials scored between 4 and 8 out of a possible 10 points on the PEDro scale. Limitations included a lack of blinded outcome assessment, inadequate handling of participant attrition (only two trials performed intention-to-treat analyses), and inadequate allocation concealment. Exercise was statistically significantly better than no exercise at reducing pain for patients with knee osteoarthritis (SMD -0.94, 95% CI -1.31 to -0.57; eight RCTs). There was evidence of substantial heterogeneity between trials (Ι²=71%). Subgroup analyses demonstrated a larger effect size for non-weight-bearing strengthening exercise (SMD -1.42, 95% CI -2.09 to -0.75; four RCTs) than for weight-bearing strengthening exercise (SMD -0.70, 95% CI -1.05 to -0.35; one RCT) and for aerobic exercise (SMD -0.45, 95% CI -0.77 to -0.13; three RCTs). There was no evidence of publication bias. Authors' conclusions Muscle-strengthening exercise, with or without weight bearing, and aerobic exercise were effective for pain relief in people with knee osteoarthritis. Non-weight-bearing strengthening exercise was more effective than weight-bearing strengthening exercise and aerobic exercise, as a short-term intervention. CRD commentary The review question was clearly stated, but the authors aimed to compare the different types of exercise against each other, but sought only trials comparing exercise with no exercise. It would have been appropriate to also seek trials that directly compared the different types of exercise. Otherwise, the search strategy appears to have been appropriate, with no language limitations, but there was no specific search for unpublished trials. Ten studies were excluded from the review because they had a lower exercise frequency, or a longer intervention duration, than the median of the identified studies. This was done to minimise clinical heterogeneity across the trials, but substantial heterogeneity was still evident. In view of the few trials included in the review, it would have been more appropriate to have included all of the relevant trials and undertaken subgroup analysis on the frequency and duration of exercise. The studies were assessed for quality using appropriate criteria, but the scoring system made it difficult to evaluate the impact of any bias on the results. Sensitivity analyses based on trial quality were not presented. The authors did not discuss a key issue in comparing exercise with no exercise: the lack of patient blinding in trials with subjective outcomes, such as pain, might contribute to any treatment effect. The included trials were small and some were at a high risk of bias. The meta-analysis appears to have been appropriate for the assessment of exercise, compared with no exercise, but it provided only limited information on the exercise interventions compared with each other. For one of the exercise subgroups, there was only one included trial. The control groups of three trials were double-counted in the meta-analysis, meaning that the confidence intervals of the pooled estimates were likely to be unduly precise.The authors acknowledged that there were insufficient trials to assess publication bias for the subgroups. In light of the limitations of both the included trials and the meta-analyses, the authors' conclusions appear to be over-optimistic. Implications of the review for practice and research Practice: The authors stated that in the short term, non-weight-bearing strengthening exercises were recommended to reduce pain in people with knee osteoarthritis. Research: The authors stated that meta-analyses of the effects of strengthening exercise and aerobic exercise on pain relief in people with knee osteoarthritis should consider trial quality and publication bias. Bibliographic details Tanaka R, Ozawa J, Kito N, Moriyama H. Efficacy of strengthening or aerobic exercise on pain relief in people with knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials. Clinical Rehabilitation 2013; 27(12): 1059-1071 Indexing Status Subject indexing assigned by NLM MeSH Databases, Bibliographic; Exercise /physiology; Exercise Therapy /methods; Humans; Osteoarthritis, Knee /rehabilitation; Pain Management /methods; Randomized Controlled Trials as Topic; Resistance Training /methods AccessionNumber 12013039066 Date bibliographic record published 01/08/2013 Date abstract record published 02/12/2014 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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