JBI checklist criteria (potential bias and threat) | Studies | |||||
---|---|---|---|---|---|---|
Burgess et al., 2011 [38] | Burgess et al., 2015 [36] | Davey et al., 2014 [33] | Davidson et al., 2008 [34] | Daws et al., 2014 [37] | Dimer et al., 2013 [35] | |
1. Is it clear in the study what is the ‘cause’ and what is the ‘effect’ (i.e. there is no confusion about which variable comes first)? (causation/reverse causation) | Yes | Yes | Yes | Yes | Yes | Yes |
2. Were the participants included in any comparisons similar? (selection bias) | Yes | Yes | Yes | Yes | Yes | Yes |
3. Were the participants included in any comparisons receiving similar treatment/care, other than the exposure or intervention of interest? (history threat/systematic difference/ contamination bias) | Yes | Yes | Yes | Yes | Yes | Yes |
4. Was there a control group? (measurement bias) | No | No | No | No | No | No |
5. Were there multiple measurements of the outcome both pre and post the intervention/exposure? (maturation threat, regression to the mean) | Yes | No | Yes | Yes | No | Yes |
6. Was follow-up complete, and if not, was follow-up adequately reported and strategies to deal with loss to follow-up employed? (attrition bias) | Yes | Yes | Yes | Yes | Yes | Yes |
7. Were the outcomes of participants included in any comparisons measured in the same way? (instrumentation/testing effects threats) | Yes | Yes | Yes | Yes | No | Yes |
8. Were outcomes measured in a reliable way? (detection/instrument/measurement bias) | Yes | Yes | Yes | Yes | No | Yes |
9. Was appropriate statistical analysis used? (performance/detection bias) | Yes | No | Yes | Yes | No | Yes |
Total (%) and quality ratinga | 8/9 (88%) Good | 6/9 (67%) Moderate | 8/9 (88%) Good | 8/9 (88%) Good | 4/9 (44%) Poor | 8/9 (88%) Good |