Smokers more likely to drop oral contraceptives

Medical Tribune June 2009 P12
David Brill

Young women who smoke are more likely to stop taking oral contraceptives (OCs), a recent study suggests.

After 6 months of follow-up, only 26 percent of smokers were still taking OCs, compared to 46 percent of non-smokers (P<0.0001).

The study included 1,598 inner-city women aged under 25 – 198 of whom were smokers. After adjustment for confounding factors, smokers were 40 percent less likely to still be taking OCs (odds ratio 0.6; 95 percent CI, 0.4 – 1.0). [Contraception 2009 May;79(5):375-8]

“The take-home message is that smokers may be risk takers and thus more likely to discontinue contraceptives,” said lead author Dr. Carolyn Westhoff, professor of obstetrics and gynecology at Columbia University, New York, US.

The findings also serve as a reminder of the need to promote the right public health messages about smoking and OC use, say the researchers. Smoking while taking OCs is widely considered to be dangerous, but evidence so far is only conclusive for women over 35.

“The public health message and package labeling that birth control pills and smoking are incompatible is a bit over-simplified. While smoking is always a bad thing, the adverse interaction with OCs doesn't apply to our youngest patients,” said Westhoff. Pushing the same message to younger women could encourage them to quit OCs rather than quit smoking, she noted.

Study subjects were enrolled at three publicly funded family planning clinics. They reported smoking status at baseline, and OC continuation at 3 and 6 months. Twelve percent of the cohort were smokers.

“Whether public health messages or clinician messages about the risk of smoking and OC use are driving the excessive discontinuation rates seen in this study deserves further study,” the researchers wrote.

“In the meanwhile, these data indicate that young smokers may be a high-risk group for premature discontinuation of OCs. Clinicians need to clarify the appropriate health messages and find ways to support young smokers in avoiding pregnancy.”

The study is a secondary analysis of a previously published trial, which found that initiating OCs in the clinic, under observation, improved short-term compliance compared to a conventional, delayed start. [Obstet Gynecol 2007 Jun;109(6):1270-6]