Summary of quality assessments—descriptive studies*
| Study | Clear objective | Study pop’n clear | Participation ≥50% | Participants: same time period and pop’n. Criteria: prespecified and uniform | Sample size: justification, power. Effect: estimate and variance | Exposure: measure prior to outcome measure | Sufficient time: exposure to outcome | Level of exposure measured | Exposure: clear, valid, reliable and consistent | Exposure: assessment more than once | Outcome: clear, valid, reliable and consistent | Outcome: blinded assessment | Loss to follow-up ≤20% | Confounders: measured and adjusted for | Quality rating—quantitative outcomes† |
| Bhar et al, 201338 | Y | Y | Y | N | N | Y | Y | NA | Y | NA | Y | N | N | N | FAIR |
| Cauley et al, 201539 | Y | Y | ? | N | N | N | Y | N | ? | NA | N | N | Y | N | POOR |
| Chlebowski et al, 201040 | Y | Y | Y | ? | N | Y | Y | N | Y | NA | Y | N | ? | N | FAIR |
| Heiney et al, 201042 | Y | Y | Y | ? | N | Y | Y | NA | Y | NA | Y | N | N | N | FAIR |
| Kumar et al, 201243 | Y | Y | ? | ? | N | ? | Y | NA | N | NA | N | N | Y | N | POOR |
| Kusek et al, 200244 | Y | Y | ? | ? | N | Y | Y | N | Y | NA | Y | N | ? | N | FAIR |
| Lee et al, 201145 | Y | Y | ? | N | N | Y | Y | N | Y | NA | Y | N | N | 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; Y, yes.