The study began with a baseline phase during which participants completed one 21/7 cycle with the ring for those using the ring prior to the study or two 21/7 cycles for those using the pill or patch prior to the study. Daily flow was assessed during this initial phase, using a scale of 0 to 4, with 4 being the heaviest. Women who completed this phase and wanted to continue using the ring (N=74) were then randomized into 2 groups (n=37) for the 6-month extended phase.
Group 1 was assigned to use the contraceptive ring with no hormone-free days. Participants were instructed to replace the rings monthly, on the same calendar day of the month. Group 2 also used the ring on a continuous basis with monthly replacement, but those who experienced breakthrough bleeding for more than 5 days were permitted to remove the ring for 4 days. Women in both groups kept a daily diary of ring usage, degree of menstrual flow, and symptomatology, including pelvic pain, headaches, and mood.
Most subjects were white (76%), nonsmokers (84%), and unmarried (68% in Group 1 and 57% in Group 2), with an average age of 28 to 29 years. Eight patients (22%) in Group 1 withdrew from the study prior to completing the 6-month extended phase, 4 of them because of side effects. Only 1 woman withdrew from Group 2, because of plans for pregnancy. No one became pregnant while using the ring.
Hormone-free interval reduced bleeding. In Group 1, the average daily flow score was slightly reduced with continuous use (from 0.33 during the 21/7 baseline phase to 0.21 in the 6-month extended phase), but researchers reported no significant difference in flow-free days. On average, 85% of the days were flow-free in the 21/7 phase, vs 89% in the extended phase.
In Group 2, flow-free days increased, from 83% in the baseline phase to 95% in the extended phase, and average flow scores fell from 0.38 to 0.17.
Overall, the 65 participants who completed 6 months of continuous ring use had fewer bleeding days per month—1.8 days, on average, vs 3.3 days during the initial 21/7 phase, but more days of spotting per month (2.5 vs 1.8 days). There was no difference between Groups 1 and 2 in pelvic pain, headache, or mood scores, and no significant difference in headache or mood scores between the baseline and continuous phases of the trial. Pelvic pain scores were lower during the extended phase, however—0.18 vs 0.32 on a scale of 0 to 10.
A high continuation rate. After the 6-month extended phase, 57 of the 65 remaining participants chose to continue using the ring for contraception, on a continuous dosing basis—a continuation rate of 88%. But more than half of the women who chose to stick with the ring (57%) decided not to take advantage of the 4-day hormone-free interval to manage breakthrough bleeding or spotting, regardless of original group assignment.
WHAT’S NEW?: The ring moves further mainstream
Continuous or extended use of the transvaginal ring may be a new idea for many patients—and physicians. But the idea may catch on in light of this study’s findings. Given the high rate of unwanted pregnancy in the United States, many women may benefit from a contraceptive that is as safe and effective as an OC but doesn’t involve a daily pill.
CAVEATS: Side effects, off-label concerns
In 2005, Oddsson et al found that women who used the ring reported more vaginitis and more leukorrhea than women who used OCs; conversely, they reported less nausea and less acne. Other side effects that are common to hormonal contraceptives, such as headache and weight gain, occurred at similar rates among women using the ring and OCs.6
However, the high proportion of patients who elected to keep using the ring at the end of the study by Sulak et al suggests that its side effects are acceptable.1 As with all contraception, however, patient preference is a key consideration. The study population was highly motivated, particularly since women who had difficulty with this means of contraception dropped out after the baseline phase of the trial.
Off-label use. Pharmacokinetic research involving the contraceptive ring has shown that hormone levels required to protect against pregnancy persist for at least 35 days after it is placed in the vagina.8 The manufacturer has data only to confirm contraceptive efficacy for up to 28 days and therefore does not recommend use beyond 4 weeks.4