Table 2

Incidence and rate ratios for idiopathic venous thromboembolism comparing third generation oral contraceptives with oral contraceptives with levonorgestrel during two study periods (separately).

Study periodProgestogenWomen with venous thromboembolismWoman years at riskCrude incidence per 100 000 person years (95% CI)Adjusted incidence ratio (95% CI)
1 (January 1993 to October 1995)Levonorgestrel1783 60020.3 (11.8 to 32.5)1.0
Desogestrel or gestodene54145 20037.2 (27.9 to 48.5)2.0 (1.2 to 3.4)
2 (January 1996 to December 1999)Levonorgestrel25108 10023.1 (15.0 to 34.1)1.0
Desogestrel or gestodene1024 30041.1 (19.7 to 75.6)1.7 (0.8 to 3.5)
  • † Mantel-Haenszel method adjusting for age by year.