Association of risk for VTE with use of low-dose extended- and continuous-cycle COCs

Concerns about elevated risk for venous thromboembolism (VTE) due to increased estrogen exposure prompted a retrospective cohort study on extended cyclic and continuous combined oral contraceptives (COCs).

Concerns about elevated risk for venous thromboembolism (VTE) due to increased estrogen exposure prompted a retrospective cohort study on extended cyclic and continuous combined oral contraceptives (COCs). Without switching the progestogen type, the researchers aimed to compare VTE risk with extended COC use, defined by 84/7 days cycles; continuous use, or 365/0 day cycles; and traditional cyclic use, characterized by 21/7 days cycle. Their study population included 733,007 new, commercially insured new users of ethinyl estradiol- or levonorgestrel-based COC products between May 2007 and September 2015. A total of 210,691 of the women began taking continuous/extended COCs during the study period, and 522,316 initiated cyclic COCs. The primary outcome was first VTE hospitalization that occurred during study followup. The researchers noted a slightly inflated VTE risk with continuous/extended COC use when compared with cyclic COC use, but the absolute risk difference was small and there was potential residual confounding. The researchers conclude that they "do not recommend selective prescribing of COCs based on the cyclic and continuous/extended type," noting that "clinicians should prescribe COCs based on patients' individual risk factors and preferences."