Table 2.
Incidence rates of leukemia and hazard ratios comparing metformin initiators versus non-metformin initiators.
| Model | Incident case number of leukemia | Cases followed | Person-year | Incidence rate (per 100,000 person-years) | Hazard ratio | 95% Confidence interval | P value |
|---|---|---|---|---|---|---|---|
| Intention-to-treat | |||||||
| Metformin (–) | 372 | 195,306 | 1,309,950.45 | 28.40 | 1.000 | ||
| Metformin (+) | 598 | 414,783 | 2,254,885.22 | 26.52 | 0.943 | (0.828–1.074) | 0.3793 |
| Per-protocol | |||||||
| Metformin (–) | 151 | 195,306 | 620,459.93 | 24.34 | 1.000 | ||
| Metformin (+) | 379 | 362,455 | 1,823,252.50 | 20.79 | 0.852 | (0.705–1.031) | 0.1000 |
Cox regression was constructed with the inverse probability of treatment-weighting using propensity scores derived from variables in Table 1 plus the date of start of follow-up.