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Bias risk of the included randomized controlled trials
| Study | Randomization | Blinding | Allocation | Baseline | Incomplete data |
|---|---|---|---|---|---|
| Kaviani et al. 2014 | None | None | None | None | None |
| Freeman et al. 2008 | None | None | None | None | None |
| Rees et al. 2008 | None | None | None | None | None |
| Su et al. 2008 | None | None | None | None | None |
