Table 2.
Quality assessment of individual study
| Study | Allocation sequence generation | Allocation concealment | Blinding | Loss to follow-up | Calculation of sample size | Statistical analysis | Intention-to-treat analysis | Level of quality |
|---|---|---|---|---|---|---|---|---|
| Guilleminault et al. (2004) [11] | A | A | B | 0 | YES | t-test and Kruskal-Wallis test | YES | B |
| Margel et al. (2006) [17] | A | A | B | 0 | YES | Student paired t-test | YES | B |
| Miyauchi et al. (2015) [12] | A | A | B | 0 | YES | Wilcoxon signed rank test | YES | B |
| McMillan et al. (2014) [18] | A | A | A | 0 | YES | t-test and Kruskal-Wallis test | YES | A |
| Liu and Liu (2001) [19] | A | B | B | 0 | YES | Student paired t-test | YES | B |
A, all quality criteria met (adequate): low risk of bias; B, one or more of the quality criteria only partly met (unclear): moderate risk of bias.