C. Mauck et al., A comparative study of the safety and efficacy of FemCap (R), a new vaginal barrier contraceptive, and the Ortho All-Flex (R) diaphragm, CONTRACEPT, 60(2), 1999, pp. 71-80
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.