Table 4. Sensitive analyses based on various exclusion criteria.

	Studies,N	RRs,95%CIs	P value	P value for heterogeneity	I2(%)
total	14	1.05(0.96–1.15)	0.291	0.000	82.8
Country
United States	7	1.01(0.87–1.17)	0.898	0.000	84.1
Europe	5	1.13(0.95–1.35)	0.168	0.001	79.7
Asia	2	1.55(0.45–5.39)	0.491	0.012	84.3
Gender
Female	11	1.07(0.98–1.17)	0.143	0.000	83.5
Male	8	1.13(0.98–1.30)	0.167	0.000	86.5
Effect measure
RRs	10	1.02(0.91–1.15)	0.712	0.000	83.9
ORs	3	1.28(0.91–1.81)	0.162	0.087	59.0
HRs	1	0.98(0.93–1.04)	0.479	NA	NA
Sample size
Large(cases ≥ 100)	11	1.03(0.95–1.13)	0.451	0.000	84.5
Small(cases <100)	3	1.72(0.67–4.41)	0.263	0.078	60.9
Adjustment for covariates
Yes	8	0.96(0.83–1.10)	0.529	0.000	75.0
No	6	1.16(1.00–1.34)	0.050	0.000	89.4
NOS score
High(≥5)	13	1.02(0.94–1.12)	0.600	0.000	80.8
Low(<5)	1	1.26(1.12–1.42)	0.000	NA	NA
Follow-up duration(years)
≥5	8	0.99(0.86–1.15)	0.978	0.000	83.0
<5	3	1.11(0.99–1.25)	0.075	0.000	87.1
NA	2	1.64(0.52–5.16)	0.394	0.030	78.8

HRs, hazard ratios, ORs, odds ratios, RRs, relative risks, CIs, confidence intervals; NA, not available.