Task Force on Postovulatory Methods of Fertility Regulation. Randomised controlled trial of levonorgestrel versus the Yuzpe regimen of combined oral contraceptives for emergency contraception. Lancet 1998; 352:428-33.
Clinical question Is emergency contraception with levonorgestrel as safe and effective as the Yuzpe regimen of combined oral contraceptives?
Background Combined oral contraceptive pills (OCPs) is currently the most commonly used method of emergency contraception. In Eastern Europe, levonorgestrel is packaged as .75 mg tablets for occasional postcoital contraception. A recently published World Health Organization-supported study conducted in Hong Kong compared the 2 regimens for emergency contraception. The study concluded that levonorgestrel was slightly more effective than combined OCPs and was also associated with significantly less vomiting (2.7% vs 22.4%).
Population studied The study enrolled a total of 1998 women from 21 centers around the world. All participants had regular menses, were not using hormonal contraception or breast-feeding, and requested emergency contraception within 72 hours of having unprotected coitus.
Study design and validity This was a double-blind, randomized trial comparing 2 regimens for emergency contraception after one act of unprotected coitus. Participants received 2 sets of 2 tablets that either contained a levonorgestrel tablet (.75 rag) and a placebo or 2 OCPs (50 [micro]g ethinyl estradiol plus .25 mg levonorgestrel). The first dose was supervised in the participating centers, and the second dose was taken at home 12 hours later. Follow-up was conducted 1 week after the expected onset of their next menses, and the women kept diaries of side effects, bleeding patterns, and any further acts of intercourse. If menses had not restarted by the follow-up visit, a pregnancy test was done. Because pregnancy was initially excluded by means of either a blood test or urine test, some pregnancies may have been missed by using the less sensitive urine assay. If there was a preponderance of one test used in either of the groups, a potential for bias exists. However, the authors included pregnancies at enrollment in their main analysis.
Outcomes measured Unintended pregnancy was the primary outcome measured using both crude and adjusted pregnancy rates. Secondary outcomes included reduction in expected pregnancies, side effects, and changes in bleeding patterns.
Results The pregnancy rates were 1.1% (95% CI, .6 - 2.0) and 3.2% (95% CI, 2.2 - 4.5) for the levonorgestrel and combined OCP methods, respectively. The crude relative risk of pregnancy was .36 (95% CI, .18 - .70) for levonorgestrel compared with the combined OCP regimen. This represented a significant reduction in unintended pregnancies in the levonorgestrel group. For every 47 patients treated with the levonorgestrel method, one unintended pregnancy would be prevented. The authors calculated that the levonorgestrel regimen prevented 85% (95% CI, 74 - 93) of expected pregnancies while the combination OCP regimen prevented 57% (95% CI, 39 - 71). Additionally, nausea, vomiting, dizziness, and fatigue were all significantly less common in the levonorgestrel group (P [is less than] .01). Bleeding patterns were similar for both treatment regimens.
Recommendations for clinical practice This study clearly demonstrates increased effectiveness of the levonorgestrel regimen for emergency contraception. Perhaps even more important clinically is the significant decrease in major side effects among women in the levonorgestrel group. The major limitation of the levonorgestrel regimen for emergency contraception in the United States is that the .75 mg tablets are not currently manufactured here. Patients would have to take 20 Ovrette tablets in 2 doses 12 hours apart, leading to a large pill burden.
[1.] Van Look PFA, Stewart F. Emergency contraception. In: Hatcher RA, Trussell J, Stewart F et al., eds. Contraceptive technology. New York, NY: Ardent Media, 1998.
COPYRIGHT 1998 Dowden Health Media, Inc.
COPYRIGHT 2004 Gale Group