The contraceptive vaginal ring compared with the combined oral contraceptive pill: a comprehensive review of randomized controlled trials.

BACKGROUND

The purpose of this review was to compare pharmacology, contraceptive efficacy, cycle control, side effects and acceptability with the combined contraceptive vaginal ring (CCVR) and combined oral contraceptives (COCs).

METHODS

All randomized controlled trials (RCTs) between the CCVR and a COC up to and including December 2006 were analyzed.

RESULTS

Twelve RCTs comparing the CCVR and a COC were identified. Systemic exposure to ethinyl estradiol (EE) with the CCVR was half of that with a 30-microg EE-containing COC with less variation in serum levels. During CCVR use, sex hormone-binding globulin and cortisol-binding globulin concentrations were significantly less increased than during COC use. Both methods showed adequate ovarian suppression and equal contraceptive efficacy. Uterine concentrations of EE and etonogestrel were not elevated with the CCVR. Cycle control achieved with the CCVR was better than that of the COC. Compliance with both methods was high. Mean blood pressure and body weight did not change in either group. Incidence of adverse events such as breast tenderness, headache and nausea was comparable, but a higher incidence of local and ring-related events led to higher discontinuation rates in the CCVR group. Both contraceptives were highly acceptable and resulted in a global improvement of sexual function. Ring users were more likely to continue with their method after study completion than COC users.

CONCLUSIONS

The vaginal ring has the same contraceptive efficacy as COCs with lower systemic EE exposure, more consistent serum EE levels and better cycle control, but more local adverse events resulting in higher discontinuation rates.