Highlights
- •Twenty seven trials compared exercise to no-exercise with a sample sufficient to detect a moderate difference.
- •Randomised controlled trials (RCTs) had a variety of treatment targets, despite sometimes using the same exercise approach.
- •Most RCTs did not match their primary outcome to their stated exercise treatment targets.
- •Matched RCTs were more likely to conclude statistically significant results in favor of exercise.
Abstract
Exercise is a core treatment for persistent non-specific low back pain (NSLBP), but
results from randomised controlled trials (RCTs) of exercise typically show only small
to moderate standardised mean differences (SMDs) compared to nonexercise controls.
The choice of primary outcome, and relationship to the specific targets of exercise
may influence this. This systematic review aimed to explore whether primary outcomes
match the exercise treatment targets used in NSLBP RCTs and the potential impact of
matching on SMDs. Included RCTs were conducted with patients with persistent NSLBP,
compared exercise to no exercise, with sample sizes >60 per arm. Screening, data extraction
and risk of bias assessment were independently undertaken by paired reviewers. Of
19272 initial titles, 27 RCTs were included with 31 treatment targets and 6 primary
outcome domains identified. Only 25% of included RCTs had primary outcomes that matched
the treatment targets. SMDs of exercise versus comparison arms were observed to be
larger in the matched (SMD .54 (95% Confidence Interval .23 to.85), P =.0006) compared to the unmatched category (SMD 0.22 (95% Confidence Interval .01,
.44) P = .04) but this difference was not statistically significant (P = .10). These exploratory findings may have implications for future teams developing
RCTs of exercise for NSLBP and warrant further investigation in larger datasets.
Perspective
This review was an exploratory study that investigated the primary outcome and treatment
targets used in RCTs of exercise for NSLBP. The SMDs of the matched group were descriptively
larger than those of the unmatched group, but further analysis with larger sample
sizes is required to have confidence in these results.
Key Words
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Published online: June 20, 2020
Footnotes
Disclosures: L Wood's PhD is funded by the Primary Care Centre Versus Arthritis, School for Primary, Community and Social Sciences, Faculty of Medicine and Health Sciences, Keele University. Prof NE Foster is a UK National Institute for Health Research (NIHR) Senior Investigator, and was supported by an NIHR Research Professorship (NIHR-RP-011-015). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. No authors have any conflicts of interest.
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