Comparative Risk of Venous Thromboembolism for Chlormadinone Acetate- and Levonorgestrel-Containing Combined Oral Contraceptives

Strategic Insights -

A recent study assessing the risk of venous thromboembolism (VTE) for two types of combined oral contraceptives (COCs) has found comparable incidence rates between chlormadinone acetate (CMA) 2 mg/ethinylestradiol (EE) 30 g and levonorgestrel (LNG) 0.15 mg/EE 30 g. The research, conducted by P. De Corte and colleagues, analyzed data from four observational studies involving 31,379 COC users, contributing to 59,167 women-years.

Key Takeaways:

  • The study assessed the risk of venous thromboembolism (VTE) for chlormadinone acetate (CMA) 2 mg/ethinylestradiol (EE) 30 g and levonorgestrel (LNG) 0.15 mg/EE 30 g combined oral contraceptives.
  • Data from four comparable, large, observational studies were pooled in a dataset comprising new users of the combined oral contraceptives.
  • Individuals with a personal history of VTE were excluded, and Cox models were performed to calculate crude and adjusted hazard ratios (HRs).
  • The incidence rates of confirmed VTE were comparable between CMA- and LNG-cohorts (9.8/10,000 woman-years [WY]; 95% confidence interval [CI]: 6.36-14.50 vs. 10.38/10,000 WY; 95% CI: 7.23-14.44, respectively).
  • The hazard ratio was 1.25 (95% CI: 0.72-2.14) after adjusting for age, BMI, family history of VTE, and current duration of use.
  • The research concluded that incidence rates of VTE were in line with previous findings of VTE incidences across various COCs.
  • The absolute risk increase remained small and in line with previous studies, with no significant differences found regarding the risk of VTE between users of CMA- and LNG-containing COCs.

Statistics:

  • 31,379 COC users exposed to either CMA 2 mg/EE 30 g or LNG 0.15 mg/EE 30 g contributed to 59,167 women-years.
  • 60 VTE were reported.
  • The hazard ratio was 1.25 (95% CI: 0.72-2.14).
  • Incidence rates of VTE were comparable between CMA- and LNG-cohorts (9.8/10,000 woman-years [WY]; 95% confidence interval [CI]: 6.36-14.50 vs. 10.38/10,000 WY; 95% CI: 7.23-14.44, respectively).

Sources:

  • P. De Corte et al. (2025). Risk of venous thromboembolism associated with chlormadinone acetate- and levonorgestrel-containing combined oral contraceptives - Insights from the retrospective RIVET-RCS study. Contraception, 111251.
  • Elsevier Science Inc, Ste 800, 230 Park Ave, New York, NY 10169, USA. (Elsevier - www.elsevier.com; Contraception - www.journals.elsevier.com/contraception/)
  • Berlin Center for Epidemiology and Health Research, Invalidenstrasse 115, 10115 Berlin, Germany.