Quality assessment of included reviews using the AMSTAR tool
| Question | Weed et al14 | McCartney et al6 | |
| 1. | Was an ‘a priori’ design provided? | Y | Y |
| 2. | Was there duplicate study selection and data extraction? | Y | Y |
| 3. | Was a comprehensive literature search performed? | Y | Y |
| 4. | Was the status of publication (ie, grey literature) used as an inclusion criterion? | Y | Y |
| 5. | Was a list of studies (included and excluded) provided? | N-only included studies | N-only included studies |
| 6. | Were the characteristics of the included studies provided? | Y | Y |
| 7. | Was the scientific quality of the included studies assessed and documented? | Y | Y |
| 8. | Was the scientific quality of the included studies used appropriately in formulating conclusions? | Y | Y |
| 9. | Were the methods used to combine the findings of studies appropriate? | Y | Y |
| 10. | Was the likelihood of publication bias assessed | Y | N/A—authors state this not possible |
| 11. | Was the conflict of interest stated? | U (although commissioned by Department of Health | Y |
| Total | 9 | 9 |
N, no; N/A, not applicable; U, unclear; Y, yes.