Table II.
Associations between metformin and overall survival.
| Pooled HR | Heterogeneity | ||||
|---|---|---|---|---|---|
| Criteria | N | Fixed (95% CI) | Random (95% CI) | I2 (%) | P-value |
| Main effect | 8 | 0.86 [0.80, 0.92] | 0.81 [0.70, 0.93] | 60 | 0.01 |
| Region | |||||
| Asian country | 2 | 0.64 [0.52, 0.80] | 0.64 [0.52, 0.80] | 0 | 0.57 |
| Western country | 6 | 0.88 [0.82, 0.95] | 0.87 [0.76, 1.00] | 50 | 0.08 |
| Diabetes type | |||||
| Diabetes | 4 | 0.85 [0.78, 0.92] | 0.76 [0.62, 0.94] | 50 | 0.11 |
| T2DM | 4 | 0.88 [0.78, 0.99] | 0.84 [0.64, 1.10] | 73 | 0.01 |
| Cancer stage | |||||
| Early | 1 | 0.54 [0.16, 1.86] | – | – | – |
| Advances | 2 | 0.97 [0.81, 1.17] | 0.89 [0.56, 1.42] | 81 | 0.02 |
| All stage | 5 | 0.84 [0.78, 0.90] | 0.78 [0.67, 0.91] | 60 | 0.04 |
| Immortal time bias | |||||
| With | 4 | 0.79 [0.69, 0.89] | 0.73 [0.59, 0.92] | 49 | 0.12 |
| Without | 4 | 0.88 [0.82, 0.96] | 0.86 [0.69, 1.07] | 68 | 0.03 |
CI, confidence interval; HRs, Hazard ratios; N, number. of studies; T2DM, type 2 diabetes mellitus.