Table 8.
Summary of quality of systematic reviews
| Review ID | Q1 - Was an ‘a priori’ design provided? | Q2 - Was there duplicate study selection and data extraction? | Q3 - Was a comprehensive literature search performed? | Q4 - Was the status of publication (i.e. grey literature) used as an inclusion criterion? | Q5 - Was a list of studies (included and excluded) provided? | Q6 - Were the characteristics of the included studies provided? | Q7 - Was the scientific quality of the included studies assessed and documented? | Q8 - Was the scientific quality of the included studies used appropriately in formulating conclusions? | Q9 - Were the methods used to combine the findings of studies appropriate? | Q10 - Was the likelihood of publication bias assessed? | Q11 - Was the conflict of interest stated? | Total score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| [25] | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 7 |
| [33] | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 6 |
| [34] | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| [35] | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 10 |
| [36] | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 5 |
| [30] | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 3 |
| [24] | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
| [21] | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 4 |
| Mean | 4.875 |
Assessment of the quality of the included reviews by application of the AMSTAR Questionnaire [28], adapted to a binary scoring – items scored 1 if present, 0 if unclear, absent or not applicable. The questionnaire is composed of 11 closed questions, with possible answers: Yes, No, Can’t Answer and Not Applicable. The quality assessment we carried out relied on the information reported in the review - we did not contact the authors of the reviews to gather information which was missing or ambiguous in their publication. As a consequence, it may be possible that the authors had performed, for example, a comprehensive literature search for their review, but they did not report this in sufficient detail in their publication. This also caused uncertainty and ambiguity between the No and Can’t Answer options, with blurred boundaries between the two. In addition, the AMSTAR questionnaire presents some double-barrelled questions (Q2, Q5, Q7) and we scored the item as present (a score of 1) only when both items in the question were answered positively. So, for example, only when both the lists of included and excluded studies were provided (Q5) a score of 1 would be awarded to the review.