Table 3

AMSTAR assessments of methodological quality

AMSTAR criteria	Burls et al13	Michiels et al14*	Ng and Lai12	Demicheli et al19	Diaz Granados et al15	Ferroni and Jefferson16*	Osterholm et al17	Villari et al18	Ahmed et al22	Dolan 2012	Thomas et al21
1. ‘A priori’ design?	No	No	No	Yes	No	No	No	No	No	Yes	Yes
2. Duplicate study selection and extraction?	Yes	Yes	Yes	Yes	No	No	No	Yes	Yes	Yes	Yes
3. Comprehensive literature search?	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes
4. Did they attempt to find unpublished studies and grey literature?	Yes	No	Yes	Yes	No	No	No	Yes	No	No	Yes
5. List of studies (included and excluded) provided?	No	No	Yes	Yes	No	No	Yes	Yes	No	No	Yes
6. Characteristics of included studies provided?	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
7. Scientific quality of included studies assessed and documented?	No	Yes	Yes	Yes	Yes	No	No	Yes	Yes	Yes	Yes
8. Scientific quality of included studies used appropriately in formulating conclusions?	No	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	No	Yes
9. Appropriate methods used to combine the findings of studies?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10. Likelihood of publication bias assessed?	No	No	No	No	Yes	No	No	Yes	No	No	Yes
11. Conflict of interest stated?	No	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes
Total risk score*	5	6	9	10	7	5	4	9	7	7	11

*Michiels et al14 and Ferroni and Jefferson16 are mainly overviews of reviews and so the AMSTAR criteria may be poorly applicable.
†Note all questions score 1 point for a ‘yes’ answer.