Table 2 Quality of bias assessment of the included studies according to the Cochrane guidelines
Study | Sequence generation | Allocation concealment | Blinding of participants, personnel and outcome assessors | Incomplete outcome data | Selective outcome reporting | Other sources of bias |
|---|---|---|---|---|---|---|
Balan et al. (1994) [18] | U | U | L | L | L | U |
Battezzati et al. (1993) [21] | L | L | L | L | L | L |
Braga et al. (2009) [22] | U | U | U | L | L | U |
Carulli et al. (1981) [32] | U | U | U | L | L | U |
Fromm et al. (1983) [23] | U | U | U | L | L | U |
Gianturco et al. (2013) [39] | L | L | U | L | L | U |
Leuschner et al. (2010) [40] | U | U | U | L | L | U |
Lindenthal et al. (2002) [33] | U | U | H | L | L | U |
Méndez-Sánchez et al. (2004) [19] | L | L | U | L | L | U |
Miettinen et al. (1995) [20] | U | U | U | L | L | U |
Nakagawa et al. (1977) [37] | U | L | L | L | L | U |
Parés et al. (2000) [34] | U | L | L | L | L | U |
Poupon et al. (1990) [35] | U | U | U | L | L | U |
Poupon et al. (1993) [38] | H | U | U | L | L | U |
Vuoristo et al. (1995) [36] | U | U | U | L | L | U |