Table 2.
Risk of bias scoring
| Article | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| Carr [13] (2009) | b | NA | c | a | None | b | a | d |
| Chew et al. [14] (2013) | a | NA | c | a | None | b | a | d |
| Doherty et al. [11] (2013) | b | NA | c | a | None | b | a | c |
| Humphrey-Murto et al. [12] (2014) | b | NA | c | a | None | b | a | d |
| Leddy et al. [15] (2011) | b | NA | c | a | None | c | a | d |
| Librrecht et al. [10] (2014) | b | NA | c | a | a | b | a | a |
1: Representativeness of the exposed cohort; 2: Selection of the non-exposed cohort; 3: Ascertainment of exposure; 4: Demonstration that outcome of interest was not present at start of study; 5: Comparability of cohorts on the basis of the design or analysis; 6: Assessment of outcome; 7: Was follow-up long enough for outcomes to occur; 8: Adequacy of follow up of cohorts.
NA, not applicable.