A self-administered monthly vaginal ring (NuvaRing) is an effective and reliable combined hormonal contraceptive that is well tolerated and accepted by users, according to a study by its manufacturer.¹ During the yearlong study, involving more than 2,000 healthy women from the United States, Canada and Europe, 21 pregnancies occurred; 11 were among women who did not adhere to the study protocol. On average, 99% of cycles included withdrawal bleeding during the fourth week of the cycle, when the ring is not used. Only 3% of women discontinued use for device-related reasons; most reported that they were satisfied with the method (85%) and would recommend it to others (90%).

The ring was designed to expose users to a lower dose of estrogen than other hormonal contraceptives while maintaining cycle control. Once in place, the device releases 15 mcg of ethinyl estradiol and 120 mcg of etonogestrel daily, at a constant rate, for 21 days; the woman removes it for the last seven days of her cycle and then inserts a new ring. Because the ring requires neither daily action on the user's part nor a visit to a health care provider for insertion or removal, it is also intended to be more convenient to use than other hormonal methods.

To evaluate the ring's efficacy, cycle control and acceptability to users, the manufacturer recruited healthy 18-40-year-old women requesting contraceptive services at 100 clinical centers. Women were eligible to participate if they had no contraindications to use of contraceptive steroids and were not recent users of hormonal implants, IUDs or injectables.

Participants were given a vaginal ring for each of the 13 cycles of the study, along with verbal and written instructions on how to insert, use and remove the device. They were told that during the three weeks of a cycle in which the ring was in place, they could remove it for up to three hours at a time, for sexual intercourse. The women underwent physical examination at the beginning of the study and a week after the third, sixth, ninth and 13th cycles. They also completed questionnaires about their level of satisfaction with the method; those who withdrew early from the study were asked to provide their reason for discontinuation. By using an interactive voice recording system or daily diary cards, participants recorded their bleeding patterns, dates of new ring insertions, and dates and duration of ring removals. Pregnancy, the study's measure of contraceptive efficacy, was assessed by tests taken at the beginning of the first cycle, the end of the last cycle and at any time pregnancy was suspected.

Of 2,322 women who began the treatment regimen, 35% discontinued use before the end of the study--15% because of adverse events and 19% for other reasons (e.g., no further need for birth control). In 86% of the 23,298 treatment cycles assessed, the women adhered to the dosing regimen--meaning that they used the ring continually for 19-23 days and then removed the device for the final 6-8 days of the cycle.

Among the 16,912 evaluated cycles in which the women had correctly followed the study protocol, 99% included withdrawal bleeding during the final week of the cycle (mean duration was about five days). Irregular bleeding (breakthrough bleeding or, more commonly, spotting in the first three weeks of the cycle) occurred in 6% of these cycles; a higher proportion of women experienced such bleeding in the first cycle than in the last cycle (6% vs. 4%). Thus, despite an ethinyl estradiol release of 15 mcg daily (a dosage at which combined oral pills have been shown to cause irregular menstrual periods), the authors comment that in general, the ring provided users with "sustained good cycle control."

Twenty-one pregnancies were documented over the course of the study. Using life-table analysis, the researchers found that the cumulative pregnancy rate was 1%. Eleven of the pregnancies occurred among women who did not adhere to the study regimen. Among women who followed the protocol, the Pearl Index revealed that 0.8 pregnancies occurred per 100 person-years of ring use.

Two-thirds of study participants reported at least one adverse event; 38% of the women in the study reported events that the investigators considered potentially method-related. Of these, the most common were headache (reported at least once by 6% of all participants), vaginal infection (6%) and vaginal discharge (5%). Others were device-related events (foreign-body sensation, complications or interruption of sexual intercourse, or ejection of the ring), weight gain, nausea, breast tenderness and acne. Among the women who withdrew from the study because they experienced adverse events, the most common reasons for discontinuation were device-related events (for 3% of all the participants), headache (1%), changes in emotional state (1%) and weight gain (1%).

For more than 97% of the ring days, participants reported no temporary removal of the ring. On the questionnaires completed at the final study visit, 18% of participants reported that they felt the vaginal ring at least occasionally during intercourse, and 32% reported that their partner felt it at least occasionally. These proportions were higher among the women who stopped using the ring before the end of the study: 23% and 37%, respectively. Ten percent of women reported that their partner objected at least occasionally to use of the ring; among those who discontinued, the proportion was 16%. Most participants reported frequently or always finding the ring easy to insert (96%) and easy to remove (98%). Overall, throughout the study, most women reported that they were satisfied or very satisfied with this contraceptive method (85%) and that they would recommend the ring to others (90%).

According to the authors, the data show that the vaginal ring is an effective contraceptive that maintains excellent cycle control, is convenient and well tolerated, and has "a good safety profile." Moreover, they comment that the ring was "highly acceptable" to the women in this study, most of whom used it correctly. And, as the authors point out, "good compliance with a contraceptive method is essential to maintain contraceptive reliability."--C. Coren

REFERENCE

1. Dieben TOM, Roumen FJME and Apter D, Efficacy, cycle control, and user acceptability of a novel combined contraceptive vaginal ring, Obstetrics & Gynecology, 2002, 100(3):585-593.