From the Guidelines
The relative risk (RR) of venous thromboembolism (VTE) for combined oral contraceptive pill (OCP) use compared to obesity is approximately similar, with both factors increasing VTE risk by about 2-4 fold independently, as supported by the most recent evidence from 1. When considering the risk of VTE, it's essential to evaluate the impact of both OCP use and obesity.
- OCP use increases the risk of VTE due to the estrogen component, which induces prothrombotic changes in coagulation factors, as noted in 1.
- Obesity, defined as a BMI ≥30 kg/m², also increases VTE risk by about 2-3 fold compared to normal-weight individuals, as mentioned in 1. The mechanism behind OCP-related VTE risk involves estrogen components inducing prothrombotic changes in coagulation factors, while obesity creates a chronic inflammatory state and impairs venous return. For obese women considering contraception, progestin-only methods (mini-pills, implants, or hormonal IUDs) may offer safer alternatives with minimal impact on VTE risk, as suggested by 1. When counseling patients about contraceptive choices, clinicians should consider individual risk factors and discuss the absolute risks rather than just relative risks to help patients make informed decisions, as emphasized in 1. It's crucial to weigh the benefits and risks of each contraceptive method, taking into account the patient's medical history, lifestyle, and preferences, to minimize the risk of VTE and ensure the best possible outcome. In the context of real-life clinical medicine, prioritizing the patient's safety and well-being is paramount, and clinicians should exercise caution when prescribing OCPs to obese women or those with other risk factors for VTE, as highlighted in 1.
From the Research
Relative Risk of Venous Thromboembolism
- The relative risk (RR) of venous thromboembolism (VTE) associated with the use of oral contraceptive pills (OCPs) versus obesity is not directly comparable from the provided studies.
- However, the studies suggest that both OCPs and obesity are risk factors for VTE.
- A study published in 2014 2 found that the use of combined oral contraceptives increased the risk of VTE compared to non-use, with a relative risk of 3.5 (95% CI 2.9-4.3).
- Another study published in 2020 3 noted that the risk of VTE varies according to the type of progestogen in combined oral contraceptives, but did not provide a direct comparison with obesity.
- A study on the effects of obesity on VTE published in 2012 4 found that obesity is associated with a moderate increase in the risk of VTE, but did not provide a specific relative risk estimate.
Comparison of Risk Factors
- The studies suggest that the risk of VTE associated with OCPs is influenced by the type and dose of estrogen and progestogen, as well as individual factors such as age and history of thrombophilia 2, 3, 5.
- Obesity is also a risk factor for VTE, and its interaction with other environmental or genetic factors can pose a significantly greater risk of VTE 4.
- However, a direct comparison of the RR of VTE associated with OCPs versus obesity is not possible based on the provided studies.