Artikel
Impact of obesity on the safety and effectiveness of oral contraceptives
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Autoren
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Kristina Bardenheuer
- ZEG – Berliner Zentrum für Epidemiologie und Gesundheitsforschung, Berlin
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Jürgen Dinger
- ZEG – Berliner Zentrum für Epidemiologie und Gesundheitsforschung, Berlin
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Sabine Möhner
- ZEG – Berliner Zentrum für Epidemiologie und Gesundheitsforschung, Berlin
| Veröffentlicht: | 20. September 2011 |
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Gliederung
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Background: The impact of obesity on the safety and effectiveness of combined oral contraceptives is unclear.
Objectives: To evaluate the impact of obesity on the safety and effectiveness of combined oral contraceptives (COC).
Methods: Four large international, prospective, controlled, non-interventional cohort studies with more than 185,000 study participants were analyzed. The studies were conducted in 8 European countries and the USA. All studies used almost identical methodology for the ascertainment of serious adverse events and treatment failure. A multifaceted 4-level follow-up procedure ensured low loss to follow-up rates. The analysis is based on Cox regression models.
Results: About 14,000 and 7,000 study participants fulfilled the criteria of WHO class I and II/III obesity, respectively. Analysis was based on 450,000 WY of observation. Incidence of serious adverse events (SAE) was statistically significantly higher among obese compared to non-obese COC users (252 vs. 186 SAE/10,000 WY). This difference was primarily based on differences in diseases of the cardiovascular and digestive systems (32 vs. 15 and 78 vs. 41 events/10,000 WY). SAE incidence for obese women who stopped COC use was substantially higher (436 SAE/10,000 WY) compared to obese COC users because of pregnancy related SAE. Incidence of venous thromboembolism (VTE) was statistically significantly higher among obese compared to non-obese COC users: WHO class II/III obesity, 36.8 VTE/10.000 WY; WHO class I obesity, 22.0 VTE/10,000 WY; BMI <20, 5.8 VTE/10,000 WY). Incidence of arterial thromboembolism was also statistically significantly higher among obese women (5.7 vs. 1.9 events/10,000 WY). Compared to non-obese COC users contraceptive failure rates were slightly higher for obese users (p < 0.01). Obese women who stopped COC use because of planned pregnancy had a slightly higher time to conception compared to non-obese women (p < 0.05).
Conclusions: Obese COC users have substantially higher health risks and slightly higher contraceptive failure rates compared to non-obese users. However, the benefits of COC use can still exceed the risks for many obese COC users because of the high health risks associated with unintended pregnancy.
