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Contraceptive efficacy of the Reality® female condom
ORIGINAL RESEARCH ARTICLE
Contraceptive Efficacy of the Realityt Female Condom James Trussell A clinical trial was conducted in 10 centers throughout Japan to assess the contraceptive efficacy and acceptability of the Realityt female condom. All 195 subjects who were enrolled contributed data on acceptability and 190 contributed data on efficacy (five subjects, none of whom became pregnant, were excluded from the efficacy analysis: two because of low coital frequency, one for not providing coital diaries or usage feeling questionnaires, and two for use of other methods of contraception). The 6-month life table probability of becoming pregnant was 3.2% during typical use and 0.8% during correct and consistent use of the condom. CONTRACEPTION 1998;58: 147–148 © 1998 Elsevier Science Inc. All rights reserved. KEY WORDS:
female condom, contraceptive efficacy
Introduction
T
he Realityt female condom is a thin, soft, loose-fitting polyurethane sheath with two flexible rings. The inner ring aids in insertion and placement at the posterior fornix. The outer ring and about 1 inch of the sheath remain outside the vagina, partially covering the labia and the base of the penis during intercourse. As the vagina expands during intercourse, the slack of the sheath is taken up so that the outer ring lies over the labia. The device is marketed in 10 countries, including the United States, the United Kingdom, Korea, and Switzerland. In the United States, the Reality female condom is available without prescription in pharmacies in a box containing three female condoms prelubricated with silicone and three containers of extra water-based lubricant. The product is approved for one-time use only for prevention of pregnancy and—for those women whose partners will not use a male condom— sexually transmitted infection. This article reports the results of a clinical trial undertaken to evaluate
the contraceptive efficacy and acceptability of the female condom (called TCF-3 in the trial) in Japan.
Materials and Methods The trial was conducted at 10 centers throughout Japan from November 1994 to October 1995. Subjects were expected to use the female condom as their only contraceptive method for 6 months and were required to be between the ages of 20 and 40 years at enrollment, to have a coital frequency of at least four times a month on average, to be willing to complete coital diaries and acceptability questionnaires, to have normal ovarian function as judged by measuring and recording body temperature (or by other methods at the discretion of the physician in charge), and to undergo a pelvic examination 1 month before the beginning of the trial and 2 weeks after discontinuing use of the condom. Volunteers were excluded for any of the following reasons: pelvic infection/inflammation, pregnant or wanting to become pregnant in the next 12 months, either partner having a history of allergy to lubricants, anatomical abnormality that would hinder use of the condom, lactating, Papanicoloau smear classification of III or more in the 6-month period before the initial gynecologic exam, a history of two or more urinary tract infections (UTI) in the past year or clinical evidence of a current UTI, either partner with a history of infertility, obvious signs or symptoms of a sexually transmitted infection, or a contraindication to pregnancy. Pregnancy tests were administered at the two gynecological exams. Efficacy was evaluated by computing singledecrement life table probabilities of pregnancy during typical use and during perfect use (when the condom was used correctly and consistently during every act of intercourse).
Results Woodrow Wilson School of Public and International Affairs and Office of Population Research, Princeton University, Princeton, New Jersey Name and address for correspondence: James Trussell, Office of Population Research, Princeton University, 21 Prospect Ave., Princeton, NJ 08544; Tel. (609)-258-4946; Fax (609)-258-1039; e-mail: [email protected] Sumitted for publication May 29, 1998 Revised July 31, 1998 Accepted for publication July 31, 1998
© 1998 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
Of 204 volunteers, 195 met the criteria for admission. Of the 195 subjects enrolled, 94.4% were married, 11.8% were nulligravid, 14.4% were nulliparous, and 95.9% had previously used male condoms; their average age was 32.0 years. No subjects were lost to follow-up. Participation of five subjects was disconISSN 0010-7824/98/$19.00 PII S0010-7824(98)00094-8
148
Trussell
tinued by the investigator (two for inadequate coital frequency, two for using other contraceptive methods, and one for not providing coital diaries or usage feeling questionnaires); none of these five became pregnant, and their experience is not included in the evaluation of efficacy. Of the 190 subjects in the efficacy analysis, 11 (5.8%) did not complete the study: six became pregnant and five discontinued use for other reasons; the 6-month life table probability of discontinuation was 5.5% (95% CI 2.4 –9.1%). Of the six pregnancies, only one occurred despite correct and consistent use of the device. The probability of becoming pregnant within 6 months was 3.2% (95% CI 0.7–5.7%) during typical use and 0.8% (95% CI 0.0 – 2.3%) during perfect use. Of the 195 enrolled subjects, 11.8% rated the female condom as very acceptable, 41.5% as acceptable, 35.9% as somewhat acceptable, 7.7% as not very acceptable, and 3.1% as not desirable at all. Of the 194 subjects who answered the question, 28.4% said they would use the device in the future, 24.7% stated they would not use it again, and the remaining 46.9% were undecided. Of 193 subjects evaluated for safety, side effects were reported by seven; none of the symptoms reported were serious and none required medical treatment.
Discussion The Reality female condom demonstrated higher contraceptive efficacy in this trial than in two previous efficacy studies of this method; the 6-month life table probability of pregnancy was 3.2% during typical use and only 0.8% during perfect (correct and consistent) use of the device. In contrast, in the first clinical trial of the female condom, conducted in the United Kingdom, the 12-month life table probability of pregnancy during typical use was 15%.1 In a second trial, 6-month probabilities of pregnancy were 12.4% and 22.2% in the United States and Latin American subgroups, respectively; the corresponding probabilities during perfect use were 2.6% and 9.5%.2 For a contraceptive method that can be used imperfectly, differences across studies in pregnancy rates during typical use are primarily governed by the extent and type of imperfect use.3 In the Japanese study, 25% of exposure to risk during typical use was imperfect-use exposure; no comparable information for the other studies is available. Differences across studies in pregnancy rates during perfect use of a contraceptive method reflect the influence of two factors: the underlying fecundity of the couple and coital frequency.3 A woman’s biological capacity to
Contraception 1998;58:147–148
conceive and to bear a child declines with age. This decline is likely to be pronounced among those who are routinely exposed to sexually transmitted infections such as chlamydia and gonorrhea. Among those not so exposed, the decline is likely to be moderate until a woman reaches her late 30s.4 Although many investigators have found that contraceptive failure rates decline with age, this effect almost surely overstates the pure age effect because age in many studies primarily captures the effect of coital frequency, which declines both with age and with marital duration.3 The mean ages of subjects in the four studies of the Reality female condom were similar, 26 years in the Latin American trial, 29 years in the US trial, 31 years in the UK trial, and 32 years in the Japanese trial. The protocols for the Latin American, US, and Japanese trials were identical, including requiring a coital frequency of at least four times a month on average to be admitted to the study. Nevertheless, the average coital frequency during the US and Japanese trials differed substantially (no information is available from the Latin American trial). The mean coital frequency per month for the 195 women in the US trial who had usable coital logs was 12.0 (median 10.7; personal communication from Markus Steiner, Family Health International). In sharp contrast, the mean coital frequency per month among the 195 women with usable coital logs in the Japanese trial was 59% lower: only 4.9 (median 4.6). Lower coital frequency in the Japanese trial could account for the lower risk of pregnancy during perfect use of the Reality female condom.
Acknowledgments The author has no financial interest in the commercial success or failure of the Reality female condom. The author is grateful to Kunio Kitamura, Director, Family Planning Clinic, Japan Family Planning Association, Inc, for generously providing the data.
References 1. Bounds W, Guillebaud J, Newman GB. Female condom (Femidom). A clinical study of its use-effectiveness and patient acceptability. Br J Fam Plann 1992;18:36 – 41. 2. Farr G, Gabelnick H, Sturgen K, Dorflinger I. Contraceptive efficacy and acceptability of the female condom. Am J Public Health 1994;84:1960 – 4. 3. Trussell J, Kost K. Contraceptive failure in the United States: a critical review of the literature. Stud Fam Plann 1987;18:237– 83. 4. Menken J, Trussell J, Larsen U. Age and infertility. Science 1986;233:1389 –94.
Contraceptive Efficacy of the Realityt Female Condom James Trussell A clinical trial was conducted in 10 centers throughout Japan to assess the contraceptive efficacy and acceptability of the Realityt female condom. All 195 subjects who were enrolled contributed data on acceptability and 190 contributed data on efficacy (five subjects, none of whom became pregnant, were excluded from the efficacy analysis: two because of low coital frequency, one for not providing coital diaries or usage feeling questionnaires, and two for use of other methods of contraception). The 6-month life table probability of becoming pregnant was 3.2% during typical use and 0.8% during correct and consistent use of the condom. CONTRACEPTION 1998;58: 147–148 © 1998 Elsevier Science Inc. All rights reserved. KEY WORDS:
female condom, contraceptive efficacy
Introduction
T
he Realityt female condom is a thin, soft, loose-fitting polyurethane sheath with two flexible rings. The inner ring aids in insertion and placement at the posterior fornix. The outer ring and about 1 inch of the sheath remain outside the vagina, partially covering the labia and the base of the penis during intercourse. As the vagina expands during intercourse, the slack of the sheath is taken up so that the outer ring lies over the labia. The device is marketed in 10 countries, including the United States, the United Kingdom, Korea, and Switzerland. In the United States, the Reality female condom is available without prescription in pharmacies in a box containing three female condoms prelubricated with silicone and three containers of extra water-based lubricant. The product is approved for one-time use only for prevention of pregnancy and—for those women whose partners will not use a male condom— sexually transmitted infection. This article reports the results of a clinical trial undertaken to evaluate
the contraceptive efficacy and acceptability of the female condom (called TCF-3 in the trial) in Japan.
Materials and Methods The trial was conducted at 10 centers throughout Japan from November 1994 to October 1995. Subjects were expected to use the female condom as their only contraceptive method for 6 months and were required to be between the ages of 20 and 40 years at enrollment, to have a coital frequency of at least four times a month on average, to be willing to complete coital diaries and acceptability questionnaires, to have normal ovarian function as judged by measuring and recording body temperature (or by other methods at the discretion of the physician in charge), and to undergo a pelvic examination 1 month before the beginning of the trial and 2 weeks after discontinuing use of the condom. Volunteers were excluded for any of the following reasons: pelvic infection/inflammation, pregnant or wanting to become pregnant in the next 12 months, either partner having a history of allergy to lubricants, anatomical abnormality that would hinder use of the condom, lactating, Papanicoloau smear classification of III or more in the 6-month period before the initial gynecologic exam, a history of two or more urinary tract infections (UTI) in the past year or clinical evidence of a current UTI, either partner with a history of infertility, obvious signs or symptoms of a sexually transmitted infection, or a contraindication to pregnancy. Pregnancy tests were administered at the two gynecological exams. Efficacy was evaluated by computing singledecrement life table probabilities of pregnancy during typical use and during perfect use (when the condom was used correctly and consistently during every act of intercourse).
Results Woodrow Wilson School of Public and International Affairs and Office of Population Research, Princeton University, Princeton, New Jersey Name and address for correspondence: James Trussell, Office of Population Research, Princeton University, 21 Prospect Ave., Princeton, NJ 08544; Tel. (609)-258-4946; Fax (609)-258-1039; e-mail: [email protected] Sumitted for publication May 29, 1998 Revised July 31, 1998 Accepted for publication July 31, 1998
© 1998 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
Of 204 volunteers, 195 met the criteria for admission. Of the 195 subjects enrolled, 94.4% were married, 11.8% were nulligravid, 14.4% were nulliparous, and 95.9% had previously used male condoms; their average age was 32.0 years. No subjects were lost to follow-up. Participation of five subjects was disconISSN 0010-7824/98/$19.00 PII S0010-7824(98)00094-8
148
Trussell
tinued by the investigator (two for inadequate coital frequency, two for using other contraceptive methods, and one for not providing coital diaries or usage feeling questionnaires); none of these five became pregnant, and their experience is not included in the evaluation of efficacy. Of the 190 subjects in the efficacy analysis, 11 (5.8%) did not complete the study: six became pregnant and five discontinued use for other reasons; the 6-month life table probability of discontinuation was 5.5% (95% CI 2.4 –9.1%). Of the six pregnancies, only one occurred despite correct and consistent use of the device. The probability of becoming pregnant within 6 months was 3.2% (95% CI 0.7–5.7%) during typical use and 0.8% (95% CI 0.0 – 2.3%) during perfect use. Of the 195 enrolled subjects, 11.8% rated the female condom as very acceptable, 41.5% as acceptable, 35.9% as somewhat acceptable, 7.7% as not very acceptable, and 3.1% as not desirable at all. Of the 194 subjects who answered the question, 28.4% said they would use the device in the future, 24.7% stated they would not use it again, and the remaining 46.9% were undecided. Of 193 subjects evaluated for safety, side effects were reported by seven; none of the symptoms reported were serious and none required medical treatment.
Discussion The Reality female condom demonstrated higher contraceptive efficacy in this trial than in two previous efficacy studies of this method; the 6-month life table probability of pregnancy was 3.2% during typical use and only 0.8% during perfect (correct and consistent) use of the device. In contrast, in the first clinical trial of the female condom, conducted in the United Kingdom, the 12-month life table probability of pregnancy during typical use was 15%.1 In a second trial, 6-month probabilities of pregnancy were 12.4% and 22.2% in the United States and Latin American subgroups, respectively; the corresponding probabilities during perfect use were 2.6% and 9.5%.2 For a contraceptive method that can be used imperfectly, differences across studies in pregnancy rates during typical use are primarily governed by the extent and type of imperfect use.3 In the Japanese study, 25% of exposure to risk during typical use was imperfect-use exposure; no comparable information for the other studies is available. Differences across studies in pregnancy rates during perfect use of a contraceptive method reflect the influence of two factors: the underlying fecundity of the couple and coital frequency.3 A woman’s biological capacity to
Contraception 1998;58:147–148
conceive and to bear a child declines with age. This decline is likely to be pronounced among those who are routinely exposed to sexually transmitted infections such as chlamydia and gonorrhea. Among those not so exposed, the decline is likely to be moderate until a woman reaches her late 30s.4 Although many investigators have found that contraceptive failure rates decline with age, this effect almost surely overstates the pure age effect because age in many studies primarily captures the effect of coital frequency, which declines both with age and with marital duration.3 The mean ages of subjects in the four studies of the Reality female condom were similar, 26 years in the Latin American trial, 29 years in the US trial, 31 years in the UK trial, and 32 years in the Japanese trial. The protocols for the Latin American, US, and Japanese trials were identical, including requiring a coital frequency of at least four times a month on average to be admitted to the study. Nevertheless, the average coital frequency during the US and Japanese trials differed substantially (no information is available from the Latin American trial). The mean coital frequency per month for the 195 women in the US trial who had usable coital logs was 12.0 (median 10.7; personal communication from Markus Steiner, Family Health International). In sharp contrast, the mean coital frequency per month among the 195 women with usable coital logs in the Japanese trial was 59% lower: only 4.9 (median 4.6). Lower coital frequency in the Japanese trial could account for the lower risk of pregnancy during perfect use of the Reality female condom.
Acknowledgments The author has no financial interest in the commercial success or failure of the Reality female condom. The author is grateful to Kunio Kitamura, Director, Family Planning Clinic, Japan Family Planning Association, Inc, for generously providing the data.
References 1. Bounds W, Guillebaud J, Newman GB. Female condom (Femidom). A clinical study of its use-effectiveness and patient acceptability. Br J Fam Plann 1992;18:36 – 41. 2. Farr G, Gabelnick H, Sturgen K, Dorflinger I. Contraceptive efficacy and acceptability of the female condom. Am J Public Health 1994;84:1960 – 4. 3. Trussell J, Kost K. Contraceptive failure in the United States: a critical review of the literature. Stud Fam Plann 1987;18:237– 83. 4. Menken J, Trussell J, Larsen U. Age and infertility. Science 1986;233:1389 –94.