Table 1. Subgroup analyses for tea consumption on risk of biliary tract cancer.
| Subgroup | No. of studies | RR (95% CI) | I2value (%) | P value |
|---|---|---|---|---|
| All studies | 8 | 0.66 (0.48, 0.85) | 81.1 | 0.001 |
| Subtype of cancer | ||||
| GC | 6 | 0.72 (0.56, 0.88) | 56.1 | 0.044 |
| EXHBDC | 5 | 0.80 (0.71, 0.89) | 0.3 | 0.404 |
| VOA | 4 | 0.78 (0.49, 1.08) | 59.8 | 0.083 |
| Study design | ||||
| case-control | 5 | 0.62 (0.44, 0.80) | 55.8 | 0.009 |
| cohort | 3 | 0.84 (0.77, 0.90) | 0.6 | 0.001 |
| Gender | ||||
| male | 2 | 0.86 (0.58, 1.13) | 0 | 0.650 |
| female | 3 | 0.65 (0.47, 0.83) | 86.7 | 0.001 |
| male and female | 5 | 0.72 (0.57, 0.87) | 24.0 | 0.246 |
| Geographic areas | ||||
| West | 4 | 0.45 (0.24, 0.65) | 36.2 | 0.152 |
| East | 4 | 0.81 (0.74, 0.88) | 21.4 | 0.001 |
| No. of case | ||||
| ≥ 200 | 3 | 0.79 (0.70, 0.88) | 48.9 | 0.081 |
| < 200 | 5 | 0.68 (0.47, 0.88) | 61.9 | 0.002 |
| Publication time | ||||
| ≥ 2000 | 4 | 0.81 (0.74, 0.88) | 21.4 | 0.240 |
| < 2000 | 4 | 0.45 (0.24,0.65) | 36.2 | 0.152 |
| Duration of fallow-up | ||||
| ≥ 5 | 2 | 0.83 (0.76, 0.90) | 11.6 | 0.340 |
| < 5 | 6 | 0.65 (0.47, 0.83) | 58.5 | 0.004 |
| Study quality | ||||
| ≥ 7 | 6 | 0.80 (0.73, 0.88) | 25.7 | 0.207 |
| < 7 | 2 | 0.55 (0.31, 0.80) | 56.5 | 0.024 |
| Adjustment for confounders | ||||
| cholelithiasis | ||||
| Yes | 2 | 0.70 (0.54, 0.85) | 0 | 0.367 |
| No | 6 | 0.71 (0.58, 0.85) | 72.4 | 0.001 |
| smoking | ||||
| Yes | 4 | 0.62 (0.38, 0.87) | 70.3 | 0.001 |
| No | 4 | 0.79 (0.70, 0.88) | 37.2 | 0.111 |
| Body Mass Index | ||||
| Yes | 3 | 0.84 (0.77, 0.90) | 0.6 | 0.412 |
| No | 5 | 0.62 (0.44, 0.80) | 55.8 | 0.009 |
| Eduction | ||||
| Yes | 5 | 0.81 (0.73, 0.90) | 30.3 | 0.158 |
| No | 3 | 0.54 (0.32, 0.75) | 69.5 | 0.008 |
RR, relative risk; CI, confidence interval.