Bayer HealthCare Pharmaceuticals is aware of two studies published in The British Medical Journal. These papers are "Risk of venous thromboembolism in users of oral contraceptives containing drospirenone or levonorgestrel: nested case-control study based on UK General Practice Research Database" by Lianne Parkin et al (1); and "Risk of non-fatal venous thromboembolism in women using oral contraceptives containing drospirenone compared with women using oral contraceptives containing levonorgestrel: case-control study using United States claims data" by Susan S. Jick et al (2).
Bayer's assessment, based on its review to date, is that the manner in which the authors applied the study methodology reported in these two publications show significant flaws and the databases used provide less reliable conclusions than are available from existing scientific evidence around the risk of developing venous thromboembolism (VTE), or blood clots, with combination oral contraceptives (COCs).
Given the already large and robust scientific body of evidence, in Bayer's opinion, these studies do not change the overall assessment about the safety of Bayer's oral contraceptives. Bayer re-affirms that the overall body of available scientific evidence continues to provide support that the risk of developing venous thromboembolism, or blood clots, in women using drospirenone-containing combination oral contraceptives is comparable to other combination birth control pills studied, including those containing levonorgestrel.
"Clinical data from a period of more than 15 years and up to 10 years of post-marketing safety study results support Bayer’s assessment that its drospirenone-containing COCs are safe and effective when used as indicated and that the risk of VTE is similar to any other low-dose estrogen COC studied, regardless of the progestogen," said Ilka Schellschmidt, MD, Head Global Medical Affairs Women's Healthcare at Bayer HealthCare Pharmaceuticals.
Combination oral contraceptives are among the most systematically studied and widely used medicines available today. Bayer’s combined oral contraceptives have been and continue to be extensively studied worldwide. Bayer has sponsored several independently-conducted, large-scale, prospective, observational safety studies on the use of COCs including the EURAS study (3) and its follow up study, i.e the LASS (4) study, as well as the Ingenix study (5) and the INAS study (6). The study protocols have been reviewed by regulatory authorities in both Europe (EMA) and the USA (FDA). They have been acknowledged by many experts in the field as among the most comprehensive and best designed studies of their kind. These studies continue to build on a large established body of well-grounded data about the safety of oral contraceptives with study designs that allow for control of key confounding factors and minimize the risk of bias. Importantly, data from these studies have consistently shown that the risk of VTE with drospirenone is comparable to that seen with other progestins, including levonorgestrel.
All birth control pills, including Bayer's, carry an increased risk of blood clots, stroke and heart attack. These serious side effects are rare. Oral contraceptives increase the tendency to develop strokes (stoppage or rupture of blood vessels in the brain) and heart attacks (blockage of blood vessels in the heart). VTE is a rare event among women using combined oral contraceptives, and pregnancy increases the risk of VTE as much or more than the use of COCs.
About Bayer HealthCare
The Bayer Group is a global enterprise with core competencies in the fields of health care, nutrition and high-tech materials. Bayer HealthCare, a subgroup of Bayer AG with annual sales of EUR 16.913 billion (2010), is one of the world’s leading, innovative companies in the healthcare and medical products industry and is based in Leverkusen, Germany. The company combines the global activities of the Animal Health, Consumer Care, Medical Care and Pharmaceuticals divisions. Bayer HealthCare's aim is to discover and manufacture products that will improve human and animal health worldwide. Bayer HealthCare has a global workforce of 55,700 employees (Dec 31, 2010) and is represented in more than 100 countries.
1. Lianne Parkin senior lecturer in epidemiology and Katrina Sharples, senior lecturer in biostatistics of the Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand; and Rohini K. Hernandez, epidemiologist and Susan S. Jick, director, Boston Collaborative Drug Surveillance Program, Boston University School of Medicine, Lexington, Massachusetts, USA
2. Susan S. Jick, director and Rohini K. Hernandez, epidemiologist, Boston Collaborative Drug Surveillance Program, Boston University School of Medicine, Lexington, Massachusetts, US
3. Dinger, Jürgen et al.: The safety of a drospirenone-containing oral contraceptive: final results from the European Active Surveillance study on Oral Contraceptives based on 142,475 women-years of observation. In: Contraception, 75, 2007, 344– 354.
4. Long-Term Active Surveillance Study for Oral Contraceptives (LASS) clinicaltrials.gov ; clinicaltrials.gov/ct2/show/NCT00676065
5. Seeger, John et al.: Risk of Thromboembolism in Women Taking Ethinylestradiol/Drospirenone and Other Oral Contraceptives. In: Obstetrics & Gynecology, Vol. 110, No. 3, September 2007, 587 – 893.
6. Dinger, Jürgen et al.: The risk of venous thromboembolism in users of a drospirenone -containing oral contraceptive with a 24-day regimen - results from the INAS-OC study. In: Fertility and Sterility, Vol 94, Issue 4, Supplement 1, September 2010, S3.