Summary of quality assessments—controlled trials*
| Study | Described as RCT | Adequate randomisation | Allocation concealment | Double-blind group assignment | Blind outcome assessment | Groups balanced on characteristics | Dropout ≤20% | Differential dropout ≤15% | High protocol adherence | Other interventions avoided | Outcomes: valid, reliable and consistent | Sufficient sample size | Outcomes and subgroups prespecified | Intention to treat | Quality rating—quantitative outcomes† |
| Cook et al, 201041 | N | NA | NA | N | ? | Y | Y | Y | ? | ? | Y | ? | ? | Y | POOR |
| Donovan et al, 200349 | Y | Y | Y | N | ? | ? | Y | Y | Y | Y | Y | Y | Y | Y | GOOD |
| Eccles et al, 201334 | Y | Y | Y | N | N | ? | Y | Y | Y | Y | Y | N | Y | Y | FAIR |
| Ford et al, 200451 | Y | ? | ? | N | N | ? | N | ? | ? | Y | Y | Y | Y | N | FAIR |
*Quality assessment checklists adapted from Study Quality Assessment Tools: National Heart, Lung, and Blood Institute (available from: https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools).
†Quality rated as good, fair or poor with respect to the quantitative recruitment-related outcomes of interest in this systematic review.
?, not reported/unable to determine; N, no; NA, not applicable; RCT, randomised controlled trial; Y, yes.