Obstet Gynecol. 2011 Mar;117(3):551-7. doi: 10.1097/AOG.0b013e31820afc46.

Continuation of prescribed compared with over-the-counter oral contraceptives.

Potter JE, McKinnon S, Hopkins K, Amastae J, Shedlin MG, Powers DA, Grossman D.

Source

Population Research Center, University of Texas at Austin, Austin, Texas 78712, USA. joe@prc.utexas.edu

Abstract

OBJECTIVE:

To estimate differences in continuation of oral contraceptive pills (OCPs) between U.S. resident women obtaining pills in U.S. family planning clinics compared with over-the-counter in Mexican pharmacies.

METHODS:

In El Paso, Texas, we recruited 514 OCP users who obtained pills over the counter from a Mexican pharmacy and 532 who obtained OCPs by prescription from a family planning clinic in El Paso. A baseline interview was followed by three consecutive surveys over 9 months. We asked about date of last supply, number of pill packs obtained, how long they planned to continue use, and experience of side effects. Retention was 90%, with only 105 women lost to follow-up.

RESULTS:

In a multivariable Cox proportional hazards model, discontinuation was higher for women who obtained pills in El Paso clinics compared with those who obtained their pills without a prescription in Mexico (hazard ratio 1.6, 95% confidence interval [CI] 1.1-2.3). Considering the number of pill packs dispensed to clinic users, discontinuation rates were higher (hazard ratio 1.8, 95% CI 1.2-2.7) for clinic users who received one to five pill packs. However, there was no difference in discontinuation between clinic users receiving six or more pill packs and users obtaining pills without a prescription.