Table 4 Subgroup analyses of tea consumption and colorectal cancer risk
Group | Studies (n) | RR (95% CI) | P | Heterogeneity test | |
|---|---|---|---|---|---|
P | I2 (%) | ||||
Total | 15 | 0.758 (0.489–1.176) | 0.216 | 0 | 99.6 |
Design | |||||
 Case–control | 3 | 1.079 (0.985–1.182) | 0.102 | 0.061 | 64.2 |
 Cohort | 11 | 0.645 (0.371–1.122) | 0.120 | 0 | 99.6 |
 Randomized controlled trials | 1 | 1.625 (1.228–2.150) | 0.001 | NA | NA |
Tea source | |||||
 Green tea | 9 | 0.049 (0.031–0.067) | 0.001 | 0 | 98.6 |
 Black tea | 2 | 0.020 (-0.018–0.058) | 0.295 | 0 | 97.5 |
 Any tea | 13 | 0.012 (0.009–0.014) | 0 | 0 | 99.8 |
Amount of tea | |||||
 < 1 | 12 | 0.008 (0.006–0.009) | 0 | 0 | 99.6 |
 ≥ 1 | 13 | 0.012 (0.010–0.014 | 0 | 0 | 99.8 |
Area1 | |||||
 America | 4 | 0.326 (0.110–0.908) | 0.043 | 0 | 99.7 |
 France | 2 | 0.954 (0.342–0.660) | 0.928 | 0 | 98 |
 UK | 2 | 1.454 (1.031–2.050) | 0.033 | 0.087 | 65.9 |
 Australia | 1 | 0.957 (0.828–1.106) | 0.553 | NA | NA |
 China | 4 | 0.906 (0.635–1.292) | 0.585 | 0 | 94 |
 Singapore | 1 | 1.107 (0.966–1.269) | 0.142 | NA | NA |
 Italy | 1 | 1.151 (1.079–1.229) | 0 | NA | NA |
Location | |||||
 Colon | 11 | 0.607 (0.365–2.264) | 0.837 | 0 | 99.7 |
 Rectal | 9 | 1.159 (0.454–2.960) | 0.758 | 0 | 99.4 |
Publication year | |||||
 < 2010 | 6 | 0.587 (0.337–1.023) | 0.060 | 0 | 98.3 |
 ≥ 2010 | 9 | 0.899 (0.493–1.639) | 0.728 | 0 | 99.7 |
Quality score | |||||
 < 7 | 8 | 0.788 (0.573–1.082) | 0.141 | 0 | 97.6 |
 ≥ 7 | 7 | 0.732 (0.360–1.488) | 0.389 | 0 | 99.7 |