15. AMSTAR scores of included systematic reviews.
| Criteria | Droogsma 2014 | Grobler 2013 | Grobler 2016 | Kristjansson 2007 | Kristjansson 2015a | Lazzerini 2013 | Ota 2015 | Sguassero 2012 |
| Was an a priori design provided? | Y | Y | Y | Y | Y | Y | Y | Y |
| Was there duplicate study selection and data extraction? | Y | Y | Y | Y | Y | Y | Y | Y |
| Was a comprehensive literature search performed? | Y | Y | Y | Y | Y | Y | Y | Y |
| Was the status of publication (i.e. grey literature) used as an exclusion criterion?a | N | Nb | N | N | Nb | N | N | Y |
| Was a list of studies (included and excluded) provided? | Y | Y | Y | Y | Y | Y | Y | Y |
| Were the characteristics of the included studies provided? | Y | Y | Y | Y | Y | Y | Y | Y |
| Was the scientific quality of the included studies assessed and documented? | Y | Y | Y | Y | Y | Y | Y | Y |
| Was the scientific quality of the included studies used appropriately in formulating conclusions? | Y | Y | Y | Y | Y | Y | Y | Y |
| Were the methods used to combine the findings of studies appropriate? | N/A | Y | Y | Y | Y | Y | Y | Y |
| Was the likelihood of publication bias assessed? (where relevant) | N/A | Nc | Y | Y | Y | Y | Y | Y |
| Was the conflict of interest stated? | Y | Y | Y | Y | Y | Y | Y | Y |
| AMSTAR scores | 8 | 10 | 11 | 11 | 11 | 11 | 11 | 10 |
| Y: yes; N: no; N/A: not applicable. | ||||||||
aFor all items except item 4, a rating of 'yes' was considered adequate. For item 4, a rating of 'no' was considered adequate. bExtensive handsearches not undertaken by authors, but trials not excluded if found. cAuthors discussed the risk involved; no formal assessment.
AMSTAR ratings (scores out of 11 criteria)
- High quality: 8–11.
- Medium quality: 4–7.
- Lower: low quality: ≤ 3.