Table 2. Evaluation of the quality of the interventions, according to the criteria of Downs and Black 15 .
| Authors, year | Report | External validity | Bias* | Confounding | Power | Sum |
|---|---|---|---|---|---|---|
| (0 to 10) | (0 to 3) | (0 to 6) | (0 to 6) | (0 to 1) | (0 to 26) | |
| Chaffee et al.8 (2013) | 10 | 3 | 5 | 6 | 1 | 25 |
| Mohebbi et al.39 (2007) | 9 | 3 | 6 | 6 | 1 | 25 |
| Vachirarojpsian et al.57 (2005) | 8 | 3 | 6 | 5 | 0 | 22 |
| Davies et al.10 (2005) | 8 | 3 | 5 | 3 | 1 | 20 |
| Raj et al.46 (2003) | 8 | 3 | 5 | 2 | 1 | 19 |
| Blinkhorn et al.2 (2003) | 6 | 1 | 6 | 3 | 1 | 17 |
| Cibuka et al.9 (2011) | 9 | 0 | 5 | 2 | 1 | 17 |
| Frazão et al.19 (2009) | 7 | 3 | 4 | 2 | 1 | 17 |
| Wagner et al.58 (2013) | 7 | 3 | 3 | 3 | 1 | 17 |
| Strippel et al.54 (2010) | 8 | 0 | 4 | 3 | 1 | 16 |
| Larsen et al.29 (2016) | 8 | 1 | 4 | 1 | 1 | 15 |
| Gauba et al.22 (2016) | 8 | 0 | 4 | 1 | 1 | 13 |
| Whittle et al.61 (2008) | 5 | 0 | 5 | 2 | 1 | 13 |
| Moskovitz et al.42 (2009) | 7 | 0 | 2 | 2 | 0 | 11 |
| Average (SD) | 7.7 (1.3) | 1.6 (1.4) | 4.6 (1.2) | 2.9 (1.6) | 0.9 (0.4) | 17.6 (4.2) |
*
Question 14 of the Downs and Black instrument was excluded.