Endpoint | Criterion to select independent studies | Numbers of studies included* | Risk ratio, Q, best estimate and 90% CI | p Value for heterogeneity |
Mortality | Larger number of cancer cases | 1, 4, 5, 6, 7, 8, 9 | 1.21 (0.51 to 1.90) | 0.79 |
Mortality | Smaller number of cancer cases | 1, 2, 3, 5 | 2.08 (1.16 to 3.01) | 0.21 |
Incidence | – | 10, 11, 12 | 0.98 (0.41 to 1.54) | 0.49 |
*Compare tables 1 and 2.