Table 1 Downs and Black risk of bias scores
Downs and Black checklist item | Tierney et al. [22] | Tierney and Simms [23] | Wundersitz et al. [24] | Kerr et al. [25] | Seminati et al. [26] | Tanabe et al. [27] | Kawasaki et al. [28] |
|---|---|---|---|---|---|---|---|
1. Study aim/hypothesis clearly defined | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
2. Clear definition of main outcomes | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
3. Patient characteristics clearly defined | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
4. Interventions used are clearly defined | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
5. Clearly defined confounders in subject groups | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
6. Study main findings are clearly defined | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
7. Random variability estimates given for main outcome data | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
8. Clearly defined adverse events that may have influenced intervention | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
9. Patients not followed up have characteristics clearly defined | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
10. Main outcome(s) probability values clearly reported | 1 | 1 | 1 | 1 | 0 | 1 | 1 |
11. Subjects asked to participate were representative of source population | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
12. Subjects prepared to participate were representative of source population | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
13. Location and delivery of study treatment were representative of source population | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
14. Opportunity taken to blind test subjects from intervention | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
15. Opportunity taken to blind researchers from intervention | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
16. Clearly defined results subject to ‘data dredging’ | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
17. Analysis adjusted for different lengths of follow-up | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
18. Use of suitable statistical tests for main outcome assessment | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
19. Reliable intervention adherence | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
20. Measures for main outcomes reliable and valid | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
21. All participants recruited from the same source population | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
22. Similar period of time used to recruit test subjects in different intervention groups | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
23. Random methods used to assign test subjects | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
24. Patients and researchers blinded to intervention until completion of recruitment | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
25. Analysis of main findings allow for sufficient confounding adjustment | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
26. Lost to follow up patients addressed | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
27. Power sufficient for study | 4 | 5 | 5 | 4 | 5 | 5 | 5 |
Quality index score (out of 31) | 15 | 20 | 16 | 15 | 15 | 16 | 16 |
Quality percentage index (%) | 48 | 65 | 52 | 48 | 48 | 52 | 52 |