Only two studies included in meta-analysis and both of them evaluated as unclear risk of bias

No serious limitations to downgrade the quality of evidence

Sequence generation was not reported in one study; allocation concealment not specified in both studies; no strategy reported to address issue of outcome assessor unblinding

Incomplete outcome data evaluated as ‘unclear’ in the pilot study; no mention of missing data or methods used to address missing data; no primary outcome stated for the pilot study

I²=50%, which may be evaluated as either low or substantial heterogeneity; this overlap affects the decision making

Magnitude of heterogeneity could be the result of high variability in the sample size and effect size which justifies the decision

Direct applicability of the included studies aims and objectives to their target populations, interventions and outcomes of interest

Boundaries of CI crossing the no effect line which downgrades the quality of evidence by one level

Number of participants needed for a single powered trial is higher than number of participants estimated from the meta-analysis; quality of evidence not downgraded on this basis

Selective outcome reporting domain evaluated low in both studies; publication bias considered as not serious by two reviewers