Dive Brief:

• Bayer’s post-market study of the permanent birth-control device, Essure, which was withdrawn from the U.S. market at the end of 2018, has been branded inadequate by the Food and Drug Administration as patients continue dropping out of the trial.
• Enrollment in the study ended in 2019, however Bayer is continuing to track participants in follow-up visits for up to five years to weigh the costs and benefits of the implanted device.
• The FDA said it saw an increase in “interim lost to follow-up rates,” prompting it to change the status of the “522” study and tell Bayer to develop and implement strategies to improve the situation.

Dive Insight:

Bayer, amid rising concerns about the birth-control device, was ordered by the FDA in February 2016 to run the study. About 3,000 women were supposed to undergo either Essure or laparoscopic tubal sterilization as part of the study, but the company’s decision to stop selling Essure in the U.S. in 2018 made it impossible to hit that target.

Bayer ultimately enrolled 1,130 patients, only 340 of whom are in the Essure group. When the FDA looked at the data gathered up to late April, it saw “more enrolled patients have discontinued the study mainly due to lost to follow-up and withdrawal from the study” since the agency’s last review in March 2021.

Almost half, 47.4%, of patients in the Essure cohort have discontinued the study, according to the regulator. Twenty-nine percent of the Essure patients have been lost to follow-up. The discontinuation and lost to follow-up figures for the control cohort are 43.5% and 33%. 

The dropout rate means the trial is no longer advancing in line with the study plan, leading the FDA to call its progress “inadequate.” The agency acknowledged the numbers of people leaving the study “may be in part due to COVID-19-related challenges,” although the prior analysis covered the first year of the pandemic, as well as “other external challenges.”  

Whatever the cause of the problem, the FDA wants Bayer to act, asking the company to “develop and implement additional strategies to improve follow-up rates in the study.” Patients are still completing the three-, four- and five-year follow-up visits. The next interim analysis will happen when all patients have completed three years of follow-up, according to the regulator.

“We believe clinical data from this postmarket study will help patients, health care providers, and the agency better understand certain complications that women who have Essure permanent birth control may experience when compared to women who undergo tubal ligation,” the FDA wrote in a note updated in March. 

The protocol presents Bayer with the opportunity to increase the retention rate. If a patient misses a follow-up visit but is then located and wishes to continue in the study, they will no longer be considered as lost to follow-up.

The FDA also provided an update on a separate post-approval study. After nine years, the rate of device removal for any reason was 18.9%, up from 17.8% one year earlier. The rate of removal remains higher in the U.S., at 19.8%, than in the rest of the world, 17.6%.