Table 2.
Risk of bias of included studies
| Criteria | Gale et al38 | Gale et al39 | Gennuso et al37 | Klenk et al40 | Klenk et al41 | Lord et al43 | Reid et al42 |
|---|---|---|---|---|---|---|---|
| Research question or objective clearly stated | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Study population clearly defined | Yes | Yes | Yes | Yes | Yes | No | Yes |
| Participation rate of eligible persons described | No | Yes | CD | Yes | Yes | CD | CD |
| Participant selection and recruitment described | Yes | Yes | No | Yes | Yes | Yes | Yes |
| Sample size justification, power description, or variance and effect estimates provided | Yes | Yes | Yes | No | No | No | No |
| Exposure(s) of interest measured prior to outcome(s) being measured | No | No | No | No | No | No | No |
| Time frame sufficient between exposure and outcome | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Independent variables clearly defined, valid, reliable, and implemented consistently across all study participants | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Exposure(s) assessed more than once over time | No | No | No | No | Yes | No | No |
| Dependent variables clearly defined, valid, reliable, and implemented consistently across all study participants | Yes | Yes | No | Yes | Yes | Yes | Yes |
| Blinding of outcome assessors | No | No | No | No | No | No | No |
| Attrition reported | Yes | CD | Yes | Yes | Yes | CD | Yes |
| Potential confounding variables measured and adjusted statistically for analyses | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Abbreviation: CD, cannot determine.