Recommendations for standardization of bleeding data analyses in contraceptive studies

To address limitations that exist with existing definitions of menstrual bleeding changes that occur with contraceptive methods, we assembled a panel to develop new recommendations for standardization of bleeding data analyses associated with contraceptive use to better inform users, clinicians, investigators, pharmaceutical companies, and regulatory agencies. We propose three criteria for assessing bleeding outcomes: pattern, flow, and duration. The descriptors within each criterion depend on whether the contraceptive is designed to result in a predictable or unpredictable bleeding pattern. Predictable pattern outcomes quantify days of scheduled, unscheduled and no bleeding, while unpredictable pattern outcomes assess frequency. Flow is quantified based on patient comparisons to their typical flow when not using contraception, with spotting representing no menstrual products use. Duration of a prolonged bleeding and/or spotting episode is more than 7 days. Studies should assess bleeding characteristics for a minimum of 12 months for 21/7, 24/4, extended cycle or continuous regimens, two years for injectables, and the full duration of use for long-acting contraceptives. Describing pattern, flow and duration as independent categories allows a fuller understanding of the bleeding outcomes and better future assessments of acceptability and continuation. Standardization of outcomes permits better comparison between studies and data synthesis; standardization will also improve the ability of clinicians and patients to understand differences between products.