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The recent network meta-analysis by Owen and colleagues1 included 89 trials of exercise for chronic low back pain (LBP) and reported low quality evidence that Pilates, stabilisation, resistance and aerobic exercises are the most effective treatments for these patients. We were surprised by how few trials were included and even more surprised by how large the estimates of treatment effect were. For example, with Pilates the effect is reported to be 1.86 standardised mean difference (SMD) in the abstract and 2.32 SMD in online supplementary table 5. These estimates are about 3–4 times effect sizes normally reported for exercise interventions in LBP and so we took a closer look at the review to try to understand what had happened. That investigation revealed some important issues that we would like to share with readers.
First, the review has missed a lot of relevant trials. The Cochrane review of exercise for chronic LBP that is currently underway has identified over 350 trials, whereas the Owen review included only 89. Even applying the restrictive selection criteria of the Owen …
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Contributors All authors contributed equally to the letter.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests The authors have published trials and systematic reviews evaluating exercise for low back pain (the topic of the review we comment upon in this letter)
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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