Table 2.
Quality of included studies
| Study | Representativeness of study sample | Ascertainment of exposure | Demonstration outcome was not present at start | Attribution bias minimized | Detection bias minimized | Follow-up time appropriate |
|---|---|---|---|---|---|---|
| Smith et al12 | Yes | Yes | Yes | Yes | Yes | Unclear |
| Salvaneschi et al13 | No | Yes | Yes | Yes | Unclear | Yes |
| Garban et al14 | Yes | Yes | Yes | Yes | Unclear | Unclear |
| Greinix et al18 | No | Yes | Yes | Yes | Unclear | Yes |
| Kanold et al15 | No | Yes | Yes | Yes | Unclear | Yes |
| Calore et al16 | No | Yes | Yes | Yes | Unclear | Yes |
| Ussowicz et al17 | No | Yes | Yes | Yes | Unclear | Unclear |