Table 6.
Risk of venous thrombosis associated with duration of use of oral contraceptive. Data are number
| Duration of use (months)* | No of thrombosis patients | No of controls | Odds ratio (95% CI)† | |||
|---|---|---|---|---|---|---|
| Total | Using levonorgestrel | Using gestodene | Using desogestrel | |||
| ≤3 | 66 | 32 | 8 | 10 | 15 | 12.6 (7.1 to 22.4) |
| >3 and ≤6 | 49 | 19 | 7 | 9 | 17 | 8.3 (4.7 to 14.5) |
| >6 and ≤12 | 63 | 31 | 4 | 9 | 26 | 7.5 (4.7 to 12.2) |
| >12 and ≤24 | 75 | 35 | 5 | 17 | 46 | 5.0 (3.4 to 7.4) |
| >24 and ≤60 | 141 | 77 | 15 | 31 | 87 | 5.0 (3.7 to 6.8) |
| >60 | 611 | 251 | 68 | 179 | 342 | 5.2 (4.3 to 6.2) |
| No oral contraceptive (reference) | 421 | — | — | — | 1102 | 1 |
*Duration of oral contraceptive use defined as time since start date of last oral contraceptive used before index date for women who used oral contraceptives at the time of the index date. For 221 users (98 patients and 125 controls) duration of use was unknown.
†Odds ratio adjusted for age.