Table S2.
Quality evaluation of studies included in this meta-analysis
| Study | Study selectiona | Outcomeb | Comparabilityc | Totald |
|---|---|---|---|---|
| Carruthers et al,1 2016 | 4 | 2 | 3 | 9 |
| Chung et al,2 2014 | 4 | 2 | 3 | 9 |
| Bleau et al,3 2014 | 3 | 1 | 2 | 6 |
| Zoller et al,4 2012 | 4 | 0 | 3 | 7 |
| Johannesdottir et al,5 2012 | 4 | 1 | 1 | 6 |
| Ramagopalan et al,6 2011 | 4 | 0 | 3 | 7 |
Notes:
a
Maximum 4 stars awarded for cohort representativeness, selection of nonexposed cohort, exposure assessment, and demonstration outcome not present at baseline.
b
Maximum 3 stars awarded for follow-up length, adequacy of follow-up, and outcome assessment.
c
Maximum 2 stars awarded for controlling for main confounders.
d
Studies receiving ≥6 points were considered high quality; a maximum of 9 points could be awarded.