A comparative study of the safety and efficacy of FemCap (R), a new vaginal barrier contraceptive, and the Ortho All-Flex (R) diaphragm

The FemCap(R) is a new silicone rubber barrier contraceptive shaped like a sailor's hat, with a dome that covers the cervix, a rim that fits into the fornices, and a brim that conforms to the vaginal walls around the cervix. It was designed to result in fewer dislodgments and less pressure on the ur ethra than the cervical cap and diaphragm, respectively, and to require les s clinician time for fitting. This was a phase II/III, multicenter, randomized, open-label, parallel grou p study of 841 women at risk for pregnancy. A subset of 42 women at one sit e underwent colposcopy. Women were randomized to use the FemCap or Ortho Al l-Flex(R) contraceptive diaphragm, both with 2% nonoxynol-9 spermicide, for 28 weeks. The objectives were to compare the two devices with regard to th eir safety and acceptability and to determine whether the probability of pr egnancy among FemCap users was no worse than that of the diaphragm (meaning not more than 6 percentage points higher). The 6-month Kaplan-Meier cumulative unadjusted typical use pregnancy probab ilities were 13.5% among FemCap users and 7.9% among diaphragm users. The a djusted risk of pregnancy among FemCap users was 1.96 times that among diap hragm users, with an upper 95% confidence limit of 3.01. Clinical equivalen ce (noninferiority) of the FemCap compared with the diaphragm, as defined i n this study, would mean that the true risk of pregnancy among FemCap users was no more than 1.73 times the pregnancy risk of diaphragm users. Because the observed upper 95% confidence limit land even the point estimate) exce eded 1.73, the probability of pregnancy among FemCap users, compared with t hat among diaphragm users, did not meet the definition of clinical equivale nce used in this study. The FemCap was believed to be safe and was associated with significantly fe wer urinary tract infections. More women reported problems with the FemCap with regard to insertion, dislodgement, and especially removal, although th eir general assessments were positive. The two devices were comparable with regard to safety and acceptability, bu t a 6-point difference in the true 6-month pregnancy probabilities of the t wo devices could not be ruled out. Further studies are needed to determine whether design modifications can simplify insertion and removal. CONTRACEPT ION 1999;60:71-80 (C) 1999 Elsevier Science Inc. All rights reserved.