Group | No. of studies | Pooled RR (95% CI) | Heterogeneity | |
---|---|---|---|---|
I2 (%) | P | |||
Subtype | ||||
III vs. II + I | 7 | 6.27 (1.89–20.77) | 92.0 | < 0.001 |
III vs. II | 7 | 5.55 (2.07–14.92) | 83.3 | < 0.001 |
II vs Ia | 6 | 1.62 (1.16–2.27) | 0.0 | 0.697 |
Design | ||||
Cohort | 7 | 5.05 (2.96–8.63) | 34.9 | 0.162 |
Case control | 5 | 3.15 (1.48–6.73) | 86.3 | < 0.001 |
Country of origin | ||||
East Asia | 3 | 4.01 (0.82–19.61) | 84.9 | < 0.001 |
Western countries | 8 | 4.65 (2.30–9.42) | 74.8 | < 0.001 |