Table 2.
Studies 2017–2020 grouped by Internal Validity (Risk of Bias) Rating.
| Studies rated using the NIHR tool for Controlled Intervention Studies | Internal Validity Rating | Studies rated using the NIHR tool for Pre-Post Studies with no Control Group | Internal Validity Rating |
|---|---|---|---|
| Cropp et al. (2019) | High | Gatta et al. (2019) | High |
| Beck et al. (2020); Jørgensen et al. (2020) | High | Pernebo et al. (2018) | High |
| Lindqvist et al. (2020) | High | Hauber et al. (2017) | High |
| Goodyer et al. (2017); Davies et al. (2020); O'Keeffe et al. (2020); Reynolds et al. (2020); O'Keeffe et al. (2019); Aitken et al. (2020) | High | Halfon and Bulut (2019); Halfon et al. (2019a,b) | High |
| Midgley et al. (2019) | High/Medium | Strangio et al. (2017) | High/Medium |
| Salzer et al. (2018) | High/Medium | Levy (2017) | Medium |
| Stefini et al. (2017) | High/Medium | Polek and McCann (2020) | Medium |
| Griffiths et al. (2019) | High/Medium | Chirico et al. (2019) | Medium |
| Hertzmann et al. (2017) | Medium | Midgley et al. (2018) | Medium/Low |
| Edginton et al. (2018) | Medium | Bo et al. (2017) | Medium/Low |
| Krischer et al. (2020) | Medium/Low | Bo et al. (2019) | Medium/Low |
| Weitkamp et al. (2017) | Medium/Low | Schenk et al. (2019) | Medium/Low |
| Weitkamp et al. (2018) | Medium/Low | Prout et al. (2019) | Medium/Low |
| Enav et al. (2019) | Medium/Low | Ryan and Jenkins (2020) | Low |
| Bernstein et al. (2019) | Low |
Where a study is rated as having “high internal validity” this means that the outcome results reported in the study have a greater probability of being truly attributed to the intervention or exposure being evaluated, and not to biases, measurement errors, or other confounding factors that may result from flaws in the design or conduct of the study.