Combined hormonal contraceptive use among women with known dyslipidemias: a systematic review of critical safety outcomes

Abstract

Context: Dyslipidemias represent a spectrum of lipid disorders that are important risk factors for cardiovascular disease. In addition, elevated triglycerides are known to be associated with pancreatitis. Though less clear, it is possible that dyslipidemias may also contribute to risk for venous thromboembolism (VTE). Ethinyl estradiol and progestogen, contained within combined hormonal contraception, are known to impact lipid metabolism.

Objectives: To evaluate from the literature whether use of combined hormonal contraception (CHC), including combined oral contraception (COC) pills, transdermal patch, vaginal ring or injectables, modifies the relative risk of acute myocardial infarction (MI), stroke, VTE or pancreatitis among women with known dyslipidemias and to determine if existing lipid abnormalities worsen with CHC use.

Methods: PubMed and the Cochrane Library databases were searched for all articles in all languages published between inception and September 2014 relevant to dyslipidemia, CHC use and serious adverse events (MI, stroke, VTE or pancreatitis). The quality of each individual study was assessed using the system for grading evidence developed by the United States Preventive Services Task Force.

Results: From 306 articles identified by our search strategy, 3 articles met inclusion criteria. In a poor-quality case-control study, women with hypercholesterolemia but no COC use had an increased risk of MI (adjusted odds ratio [adj OR] 3.3, 95% confidence interval [CI] 1.6-6.8), as did women who used COCs but did not have hypercholesterolemia (adj OR 2.0, 95% CI 1.4-2.8), compared with non-COC users without hypercholesterolemia; women with both COC use and hypercholesterolemia had an adjusted OR of 24.7 (95% CI 5.6-108.5) compared with women with neither risk factor. A poor-quality cohort study examined COC users and reported that women with dyslipidemia had increased risk for VTE [crude risk ratio (RR) 1.39, 95% CI 1.04-1.85] and transient ischemic attacks or cerebrovascular accidents (CVAs) (RR 1.76, 95% CI 1.51-2.06) compared to those without dyslipidemia. Another poor-quality cohort study provided direct evidence on changes in lipid levels among COC users with dyslipidemia. A minority of women with elevated total cholesterol or triglyceride levels at baseline showed normal results (25% and 28%, respectively) after 6 cycles of COC use. No evidence regarding risks associated with use of other CHC methods was identified. No evidence was identified for the outcome of pancreatitis.

Conclusion: Limited data from poor-quality observational studies suggest that women with known dyslipidemias using CHC may be at increased risk for MI and may experience a minimal increase in risk for CVA or VTE. No evidence was identified on risk for pancreatitis in this context. The impact of CHC exposure on the status of lipid abnormalities over time, an intermediate marker for disease, is also unclear. Given the significant limitations of this body of evidence, the importance of access to effective contraception and theoretical concerns raised about the use of CHCs by women with known dyslipidemias, additional rigorous studies are needed to best estimate true associations. Contraceptive decision making should include consideration of both the known and theoretical risks of a given CHC method, safety and acceptability of alternative contraceptive methods, and risks associated with unintended pregnancy.

Keywords: Combined hormonal contraception; Dyslipidemias; Myocardial infarction; Pancreatitis; Stroke; Venous thromboembolism.