Table 3.

Sensitivity analysis after each study was excluded by turns.

Study omitted	RR with 95% CI for remainders	Heterogeneity
		I 2	P
Parazzini et al. (27)	2.61 (0.97–7.05), P = 0.058	82.5%	0.003
Chung et al. (24)	4.46 (2.58–7.7), P < 0.001	42%	0.178
Koehn et al. (26)	3.59 (1.05–12.28), P = 0.042	96.6%	<0.001
Tibaek et al. (29)	2.59 (0.93–7.19), P = 0.068	96.4%	<0.001

RR, relative risk; CI, confidence interval.