Where possible, standardised mean differences (also known as effect sizes) with 95% confidence intervals were calculated using web-based software [11]. For dichotomous outcomes, odds ratios were calculated.
The results of the included trials were combined qualitatively using a best-evidence synthesis [12]:
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Strong: consistent findings among high-quality randomised controlled trials (RCTs).
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Moderate: consistent findings among multiple low-quality RCTs and/or non-randomised clinical controlled trials (CCTs) and/or one high-quality RCT.
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Limited: one low-quality RCT or CCT or consistent findings from pre- to post-trials.
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Insufficient: insufficient evidence to support or refute the effectiveness of the intervention with no RCT and/or CCT, or a single pre–post-trial.
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Conflicting: inconsistent findings among multiple trials.