Standardized outcome measures for reporting results from male contraceptive efficacy trials.

Background: Standardized methodology for reporting outcomes for male contraceptive trials has not been published. For male contraceptive studies that suppress spermatogenesis, contraceptive failures can occur during the sperm suppression phase or by sperm rebound or due to an unintended pregnancy during the efficacy phase. These three types of contraceptive failure differ from female contraceptives studies and necessitate a novel approach to reporting results from male contraceptive efficacy trials.

Methods: A standardized approach to reporting contraceptive outcomes for male contraceptive efficacy trials is proposed highlighting the three types of contraceptive failure: suppression failure, sperm rebound, and unintended pregnancy. This approach is used to retrospectively analyze published male contraceptive efficacy studies. Data on adverse events and other dropouts from these trials and data from condom use are also presented to give an overall picture of the contraceptive effectiveness of these methods.

Results: In 2217 men enrolled in the five male hormonal contraceptive efficacy studies included in the analysis, the suppression failure rate was 3.3% (95% CI: 2.6-4.2). The sperm rebound rate during efficacy was 1.4% (95% CI: 0.9%-1.9%), and the unintended pregnancy rate during efficacy was 1.1% (95% CI: 0.8%-1.7%). The combined contraceptive failure rate was 6.2% (95% CI: 5.2%-7.3%). In these trials, dropouts from adverse events occurred in 3.9% (95% CI: 3.1%-4.9%) of men, while discontinuations for other reasons occurred for 20% (95% CI: 18%-22%) of men. In total, 70% (95% CI: 68%-72%) of men experienced effective contraception.

Conclusions: Contraceptive failure in male contraceptive trials may be described with a three-outcome approach. Combining contraceptive failure measures with adverse event and dropout rates results in a clearer understanding of contraceptive effectiveness for the method under study.