Table 2.
Methodological quality of included studies
| Study reference | Selection bias | Confounders | Data collection—outcome | Data collection—size | Withdrawals and drop-outs | Analyses |
|---|---|---|---|---|---|---|
| Allison et al. (2013) | WEAK | WEAK | STRONG | MOD | N/A | MOD |
| Angell and Test (1992) | WEAK | STRONG | STRONG | WEAK | MOD | MOD |
| Becker et al. (1998) | MOD | STRONG | STRONG | STRONG | N/A | STRONG |
| Cechnicki & Wojciechowska (2008)1 | WEAK | WEAK | STRONG | STRONG | N/A | MOD |
| Cechnicki et al. (2008)1 | WEAK | WEAK | WEAK | STRONG | N/A | MOD |
| Cohen et al (1997) | MOD | STRONG | STRONG | STRONG | N/A | STRONG |
| Cresswell et al. (1992) | WEAK | WEAK | STRONG | STRONG | N/A | WEAK |
| Dixon et al. (2001)2 | WEAK | STRONG | STRONG | WEAK | N/A | STRONG |
| Goldberg et al. (2003)2 | MOD | WEAK | STRONG | WEAK | N/A | STRONG |
| Hamilton, et al. (1989) | WEAK | WEAK | STRONG | STRONG | N/A | MOD |
| Horan et al. (2006) | WEAK | WEAK | STRONG | STRONG | WEAK | MOD |
| Howard, Leese & Thornicroft (2000) | MOD | STRONG | STRONG | STRONG | WEAK | STRONG |
| Macdonald et al. (1998) | WEAK | STRONG | STRONG | MOD | N/A | STRONG |
| Sibitz et al. (2011) | MOD | STRONG | STRONG | WEAK | N/A | STRONG |
| Thorup et al. (2006) | WEAK | MOD | STRONG | MOD | MOD | STRONG |
| Wojciechow et al. (2002) | WEAK | WEAK | STRONG | STRONG | N/A | MOD |
MOD moderate, N/A not applicable
1,2Overlapping samples