Table 2.
Risk of bias and methodological quality assessment of included studies
| Study (reference) | Sequence generation | Allocation concealment | Blinding | Incomplete outcome data | Selective reporting | Other bias | Follow-up period (>24 h) | Summary |
|---|---|---|---|---|---|---|---|---|
| Catlin et al. (1991)32 | Unclear | Unclear | Low | High | Unclear | Unclear | Low | Unclear |
| Volk et al. (1993)55 | Unclear | Low | Low | High | Low | High | Low | Unclear |
| Ohlms et al. (1995)47 | Unclear | Low | Low | High | Low | Low | Low | Unclear |
| April et al. (1996)30 | Low | Low | Low | Low | Low | Low | High | High |
| Tom et al. (1996)53 | Unclear | Low | Low | High | Low | Unclear | Low | Unclear |
| Kim et al. (1998)39 | Unclear | High | High | Unclear | Low | High | Low | High |
| Carr et al. (1999)31 | Low | Unclear | Low | High | Low | Low | Low | Unclear |
| Holt et al. (2000)36 | Low | Low | Low | Low | Low | Low | Low | Low |
| Nawasreh et al. (2000)46 | Unclear | High | High | Low | High | Unclear | High | High |
| Palme et al. (2000)48 | Unclear | Low | Low | Unclear | Low | Unclear | Low | Unclear |
| Giannoni et al. (2002)33 | Low | Low | Low | Low | Low | Low | Low | Low |
| Güne et al. (2002)34 | Unclear | High | Unclear | Low | Low | Unclear | High | High |
| Stewart et al. (2002)52 | Low | Low | Low | High | Low | Low | Low | Unclear |
| Hanasono et al. (2004)35 | Low | Low | Low | Low | Low | Low | Low | Low |
| Samarkandi et al. (2004)51 | Low | Unclear | Low | Low | Unclear | Low | High | High |
| Malde et al. (2005)41 | Low | Low | Low | Low | Low | Low | Low | Low |
| Trujillo et al. (2005)54 | Low | Unclear | Low | Low | Unclear | Low | Low | Unclear |
| Kaan et al. (2006)37 | Low | Unclear | Low | Low | Low | Low | High | High |
| Kaufmann et al. (2006)38 | Unclear | High | High | High | Low | High | Low | High |
| McKean et al. (2006)43 | Low | Low | Low | High | Low | Low | Low | Unclear |
| Mohammad et al. (2006)45 | Unclear | Unclear | High | Unclear | Unclear | High | Unclear | High |
| Alajmi et al. (2008)28 | High | High | High | Low | Low | High | Low | High |
| Czarnetzki et al. (2008)12 | Low | Low | Low | Low | Low | High | Low | Unclear |
| Lachance et al. (2008)40 | Low | Low | Low | Low | Low | Low | Low | Low |
| Rujirojindakul et al. (2008)50 | Low | Low | Low | Low | Low | Low | Low | Low |
| Ammar et al. (2009)29 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Unclear |
| Mohamed et al. (2009)44 | Unclear | High | Low | Low | Low | Low | High | High |
| Rabbani et al. (2010)49 | High | High | High | Low | Unclear | High | High | High |
| Mathiesen et al. (2011)42 | Low | Low | Low | Low | Low | Low | Low | Low |