46 mm size vaginal ring most preferred and had maximum adherence among women, suggests study
Researchers have found in a new study that while the 46mm vaginal ring was preferred by more women and had higher adherence rates, the 56mm ring was equally acceptable and had fewer expulsions or removals. These findings confirm that the current 54-58mm diameter vaginal rings are effective and well-accepted. Future research should explore other mechanical attributes, such as compressibility, and assess ring preferences across different populations. This study was conducted by Barbara F. and fellow researchers published in the American Journal of Obstetrics and Gynecology.
A total of 24 sexually active, HIV-negative women aged 18-40 years were invited to participate in an open-label three-way crossover study in Atlanta, GA and Bronx, NY. Each participant inserted three unmedicated silicone vaginal rings of different external diameters (46, 56, and 66 mm) in a continuous manner up to around 30 days (90 days altogether). Adherence was defined as no more than 30 minutes out of 24 hours; additional factors focused on were expulsion rates, reasons for removal, and overall acceptability. Also assessed were end-of-study ring preferences, and statistical analyses for determination of significant differences between them were performed.
Key findings
• The findings also highlighted user preference, where at the study's conclusion, 59% of participants preferred the smallest ring (46 mm), whereas only 18% preferred the 56 mm and 66 mm rings (p=0.0045).
• Adherence rate: There were no significant differences in adherence across any of the rings, wherein adherence was reported to be generalized at 78%, 75%, and 59% for the 46 mm, 56 mm, and 66 mm rings, respectively (p=0.30).
• Expulsions and removals: Compared to the 56 mm ring, expulsions were found to be more likely for both the 46 mm ring (OR 5.72, 95% CI: 1.25-26.1) and the 66 mm ring (OR 25.9, 95% CI: 6.11-109).
• Greater odds of being out (removal or expulsion) were reported for the 66 mm compared to the 56 mm (OR 6.50, 95% CI: 3.46-12.2).
• Acceptability scores were the same statistically, with 46 mm and 56 mm rings receiving a rating of 4.54/5, which was also significantly higher than that of the 66 mm, rated 3.94/5 (p<0.001).
The study confirms the importance of acceptability and functionality for the vaginal ring diameter of 54-58mm used mainly; though the most preferred is the 46mm, less expulsion was noted in the 56mm ring with equal acceptability. Future studies need to look into different parameters, similar to the physical attributes of the vaginal rings, for optimizing the future designs of the ring across larger populations.
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