Table 2.
Assessment of risk of bias in individual studies
| Study | Selection bias | Performance bias | Detection bias | Attrition bias | Reporting bias |
|---|---|---|---|---|---|
| Lundmarck et al. [12] | − | − | − | ? | − |
| Koelch et al. [13] | ? | ? | − | − | + |
| Lundmarck et al. [14] | − | − | − | ? | − |
| Taurines et al. [15] | ? | ? | − | − | + |
| Reis et al. [16] | ? | ? | − | ? | + |
| Reis et al. [17] | + | ? | − | ? | ? |
| Spigset et al. [18] | − | − | − | − | − |
| Carrillo et al. [19] | − | − | − | − | ? |
| Yoshimura et al. [20] | − | + | − | − | ? |
| Gerstenberg et al. [21] | − | − | − | ? | ? |
| Sugahara et al. [22] | ? | ? | − | − | ? |
| Katoh et al. [23] | + | − | − | − | ? |
| Suzuki et al. [24] | + | − | − | − | − |
| Reis et al. [25] | + | ? | − | ? | ? |
| Unterecker et al. [26] | − | − | − | ? | − |
| Fric et al. [27] | + | − | − | ? | − |
| Lobo et al. [28] | − | − | − | − | − |
| Ishida et al. [29] | ? | − | − | − | − |
| Lind et al. [30] | − | − | − | − | − |
| Sirot et al. [31] | + | − | ? | − | − |
| Hsyu et al. [32] | + | − | − | − | + |
+ high risk of bias, – low risk of bias, ? unclear risk of bias