The contraceptive sponge's protection against Chlamydia trachomatis and Neisseria gonorrhoeae

Topical microbicides for preventing sexually transmitted infections

BACKGROUND

This is a updated version of our Cochrane Review published in Issue 6, 2012. Sexually-transmitted infections (STIs) continue to rise worldwide, imposing an enormous morbidity and mortality burden. Effective prevention strategies, including microbicides, are needed to achieve the goals of the World Heath Organization (WHO) global strategy for the prevention and control of these infections.

OBJECTIVES

To determine the effectiveness and safety of topical microbicides for preventing acquisition of STIs, including HIV.

SEARCH METHODS

We undertook a comprehensive search of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS, CLIB, Web of Science, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, and reference lists of relevant articles up to August 2020. In addition, we contacted relevant organisations and experts.

SELECTION CRITERIA

We included randomised controlled trials of vaginal microbicides compared to placebo (except for nonoxynol-9 because it is covered in related Cochrane Reviews). Eligible participants were sexually-active non-pregnant, WSM and MSM, who had no laboratory confirmed STIs.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected studies, extracted data, and assessed risks of bias in duplicate, resolving differences by consensus. We conducted a fixed-effect meta-analysis, stratified by type of microbicide, and assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included eight trials from the earlier version of the review and four new trials, i.e. a total of 12 trials with 32,464 participants (all WSM). We did not find any eligible study that enrolled MSM or reported fungal STI as an outcome. We have no study awaiting assessment. All 12 trials were conducted in sub-Saharan Africa, with one having a study site in the USA, and another having a site in India. Vaginal microbicides tested were BufferGel and PRO 2000 (1 trial, 3101 women), Carraguard (1 trial, 6202 women), cellulose sulphate (2 trials, 3069 women), dapivirine (2 trials, 4588 women), PRO 2000 (1 trial, 9385 women), C31G (SAVVY) (2 trials, 4295 women), and tenofovir (3 trials, 4958 women). All microbicides were compared to placebo and all trials had low risk of bias. Dapivirine probably reduces the risk of acquiring HIV infection: risk ratio (RR) 0.71, (95% confidence interval (CI) 0.57 to 0.89, I² = 0%, 2 trials, 4588 women; moderate-certainty evidence). The other microbicides may result in little to no difference in the risk of acquiring HIV (low-certainty evidence); including tenofovir (RR 0.83, 95% CI 0.68 to 1.02, cellulose sulphate (RR 1.20, 95% CI 0.74 to 1.95, BufferGel (RR 1.05, 95% CI 0.73 to 1.52), Carraguard (RR 0.89, 95% CI 0.71 to 1.11), PRO 2000 (RR 0.93, 95% CI 0.77 to 1.14), and SAVVY (RR 1.38, 95% CI 0.79 to 2.41). Existing evidence suggests that cellulose sulphate (RR 0.99, 95% CI 0.37 to 2.62, 1 trial, 1425 women), and PRO 2000 (RR 0.95, 95% CI 0.73 to 1.23) may result in little to no difference in the risk of getting herpes simplex virus type 2 infection (low-certainty evidence). Two studies reported data on tenofovir's effect on this virus. One suggested that tenofovir may reduce the risk (RR 0.55, 95% CI 0.36 to 0.82; 224 participants) while the other did not find evidence of an effect (RR 0.94, 95% CI 0.85 to 1.03; 1003 participants). We have not reported the pooled result because of substantial heterogeneity of effect between the two studies (l² = 85%). The evidence also suggests that dapivirine (RR 1.70, 95% CI 0.63 to 4.59), tenofovir (RR 1.27, 95% CI 0.58 to 2.78), cellulose sulphate (RR 0.69, 95% CI 0.26 to 1.81), and (Carraguard (RR 1.07, 95% CI 0.75 to 1.52) may have little or no effect on the risk of acquiring syphilis (low-certainty evidence). In addition, dapivirine (RR 0.97, 95% CI 0.89 to 1.07), tenofovir (RR 0.90, 95% CI 0.71 to 1.13), cellulose sulphate (RR 0.70, 95% CI 0.49 to 0.99), BufferGel (RR 0.97, 95% CI 0.65 to 1.45), Carraguard (RR 0.96, 95% CI 0.83 to 1.12), and PRO 2000 (RR 1.01, 95% CI 0.84 to 1.22) may result in little to no difference in the risk of acquiring chlamydia infection (low-certainty evidence). The evidence also suggests that current topical microbicides may not have an effect on the risk of acquiring gonorrhoea, condyloma acuminatum, trichomoniasis, or human papillomavirus infection (low-certainty evidence). Microbicide use in the 12 trials, compared to placebo, did not lead to any difference in adverse event rates. No study reported on acceptability of the intervention.  AUTHORS' CONCLUSIONS: Current evidence shows that vaginal dapivirine microbicide probably reduces HIV acquisition in women who have sex with men. Other types of vaginal microbicides have not shown evidence of an effect on acquisition of STIs, including HIV. Further research should continue on the development and testing of new microbicides.

Topical microbicides for prevention of sexually transmitted infections

BACKGROUND

Two decades of research on topical microbicides for prevention of sexually transmitted infections (STIs) have had limited success. However, new microbicide randomised controlled trial (RCT) data have recently been published; but these have not yet been the subject of a systematic review.

OBJECTIVES

To determine the effects of topical microbicides for prevention of the acquisition of STIs, including human immunodeficiency virus (HIV) infection, by women from men and by men who have sex with men (MSM).

SEARCH METHODS

In July 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE, Web of Science, NLM Gateway, CLIB, AIDS Education Global Information System, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform; handsearched reference lists of relevant articles and contacted relevant organisations and experts.

SELECTION CRITERIA

RCTs of topical microbicides (except Nonoxynol-9) in sexually active, HIV-negative women or MSM. We excluded Nonoxynol-9 because previous systematic reviews showed that it does not have a significant effect on HIV or STIs.

DATA COLLECTION AND ANALYSIS

We assessed study eligibility, extracted data and assessed risk of bias in duplicate; resolving differences by discussion and consensus. We then conducted fixed-effect meta-analysis, stratified by type of microbicide.

MAIN RESULTS

We found that by the end of 2011, nine microbicide RCTs had either been conducted to term (one BufferGel and 0.5% PRO 2000, one Carraguard and one tenofovir trial) or stopped early due to safety concerns (two cellulose sulphate trials) or insufficient rate of HIV infection and low likelihood of showing a protective effect (one 2% PRO 2000, one tenofovir and two SAVVY trials). The nine RCTs enrolled 31,941 sexually active women between 2004 and 2011; in Benin, Ghana, Malawi, Nigeria, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, India, and the US. A small proof-of-concept RCT found that tenofovir (a nucleotide reverse transcriptase inhibitor) reduced the risk of HIV acquisition (one trial, 889 women; risk ratio (RR) 0.63; 95% CI 0.43 to 0.93). Effectiveness data are not yet available from the second tenofovir RCT that enrolled 5000 women and was stopped early due to low likelihood of showing a protective effect. We found no evidence of an effect on HIV acquisition for cellulose sulphate (2 trials, n = 3069; RR 1.20; 95% CI 0.74 to 1.95), SAVVY (two trials, n = 4295; RR 1.38; 95% CI 0.79 to 2.41), Carraguard (one trial, n = 6202; RR 0.89; 95% CI 0.71 to 1.11), PRO 2000 (two trials, n = 12,486; RR 0.93, 95% CI 0.77 to 1.14) and BufferGel (one trial, n = 1546; RR 1.05; 95% CI 0.73 to 1.52). Tenofovir reduced the incidence of herpes simplex virus type 2 (HSV-2) infection (one trial, 426 women; RR 0.55; 95% CI 0.37 to 0.83) and cellulose sulphate reduced the risk of chlamydia infection (two trials, n = 3069; RR 0.70, 95% CI 0.49 to 0.99). However, there was no evidence of an effect of any microbicide on the acquisition of gonorrhoea, syphilis, condyloma acuminatum, trichomoniasis, or human papillomavirus (HPV) infection. A substudy of the Carraguard trial found the prevalence of high-risk HPV infection (HR-HPV) to be 23.5% in women on Carraguard and 23.0% on placebo (n = 1718; RR 1.02; 95% CI 0.86 to 1.21). After controlling for HR-HPV risk factors, the authors found that compliant Carraguard users were 0.62 (95% CI 0.41 to 0.94) times as likely to be HR-HPV positive as compliant placebo users. Overall, there was no significant difference in the incidence of adverse events between microbicide and placebo groups.

AUTHORS' CONCLUSIONS

Limited evidence suggests that vaginal tenofovir microbicides may reduce the risk of acquisition of HIV and HSV-2 infections in women; but other types of topical microbicides have not shown evidence of an effect on HIV or STI acquisition. Therefore, there is not enough evidence to recommend topical microbicides for HIV or STI prevention at present. Further studies are needed to confirm the beneficial effects of tenofovir microbicide gel in vaginal sex. In addition, further research should continue on the development and testing of new microbicides. If the effectiveness of the tenofovir and/or other microbicides is confirmed in further studies, there will need to be a clear pathway to rapid regulatory approval. Successful launch of the effective gel would depend on having in place appropriate mechanisms for distribution to the women who need it, along with a strategy for ensuring that they use it correctly.

Sponge versus diaphragm for contraception: a Cochrane review

The contraceptive vaginal sponge was developed as an alternative to the contraceptive diaphragm. Unlike the diaphragm, the sponge can be used for more than one coital act within 24 h without the insertion of additional spermicide, and it does not require fitting or a prescription from a physician. We conducted a systematic review of randomized controlled trials that compared the vaginal contraceptive sponge with the diaphragm used with a spermicide in order to evaluate the efficacy and continuation rates of the two devices. The sponge was statistically significantly less effective in preventing overall pregnancy than was the diaphragm in the two trials that met our inclusion criteria. The 12-month cumulative life table termination rates per 100 women for overall pregnancy were 17.4 for the sponge versus 12.8 for the diaphragm in the larger US trial, and 24.5 for the sponge and 10.9 for the diaphragm in the UK trial. Similarly, discontinuation rates at 12 months were higher with the sponge than with the diaphragm [odds ratio 1.3; 95% confidence interval (CI) 1.1-1.6]. Allergic-type reactions were more common with the sponge in both trials, although the frequency of discontinuation for discomfort differed in the two trials. Other randomized controlled trials will be needed to resolve the role of spermicides in preventing sexually transmitted infections or in causing adverse effects.

Sponge versus diaphragm for contraception

BACKGROUND

The contraceptive vaginal sponge was developed as an alternative to the contraceptive diaphragm. The sponge, made of polyurethane impregnated with nonoxynol-9 (1g), releases 125 mg of the spermicide over 24 h of use. Unlike the diaphragm, the sponge can be used for more than one coital act within 24 h without the insertion of additional spermicide, and the sponge does not require fitting or a prescription from a physician. How the sponge compares with the diaphragm in terms of efficacy and continuation is not clear.

OBJECTIVES

To compare the efficacy and continuation rates of the sponge compared with the diaphragm (used with nonoxynol-9 as a spermicide). Our a priori hypothesis was that the sponge would have a higher failure rate and higher discontinuation rates than the diaphragm.

SEARCH STRATEGY

We searched the computerized databases MEDLINE, EMBASE, Popline, LILACS, and the Cochrane Controlled Trials Register. In addition, we searched the reference lists of all potentially relevant articles and book chapters. We also contacted investigators involved with both trials identified to seek other published or unpublished trials.

SELECTION CRITERIA

We included randomized controlled trials comparing the vaginal contraceptive sponge (Today; Collatex) with any diaphragm used with nonoxynol-9 to prevent pregnancy.

DATA COLLECTION AND ANALYSIS

We examined the studies identified through the literature searches for possible inclusion and evaluated their methodological quality using the Cochrane guidelines. We contacted an author involved with both published trials for supplementary information about randomization and allocation concealment. We entered data into RevMan 4.1 and calculated Peto odds ratios for overall pregnancy and 12-month discontinuation using numbers of women as the denominator. We also abstracted 12-month cumulative life-table ratios for these same outcomes, but were unable to aggregate these data.

MAIN RESULTS

The sponge was statistically significantly less effective in both trials in preventing overall pregnancy than was the diaphragm. The 12-month cumulative life-table termination rates per 100 women for overall pregnancy were 17.4 for the sponge versus 12.8 for the diaphragm in the larger U.S. trial and 24.5 for the sponge and 10.9 for the diaphragm in the U.K. trial. Similarly, discontinuation rates at 12 months were higher with the sponge than with the diaphragm (odds ratio 1.3; 95% CI 1.1-1.6). Allergic-type reactions were more common with the sponge in both trials, although the frequency of discontinuation for discomfort differed in the two trials.

REVIEWER'S CONCLUSIONS

The sponge was less effective than the diaphragm in preventing pregnancy. Discontinuation rates were higher at 12 months as well. Other randomized controlled trials will be needed to resolve the role of spermicides in preventing sexually transmitted infections or in causing adverse effects.

Safety study of nonoxynol-9 as a vaginal microbicide: evidence of adverse effects

Nonoxynol-9 (N-9) is virucidal in vitro, and is therefore a candidate microbicide for preventing sexual transmission of HIV. However, the activity of N-9 is nonspecific, suggesting that virucidal levels may produce adverse effects including epithelial disruption, inflammation of the genital mucosa, or both. A randomized placebo controlled trial of daily use of 100 mg of N-9 took place for 1 week in 40 female volunteers. Outcome measures included symptoms, colposcopic and histologic changes in the genital tract, and impact on vaginal flora. Genital irritation was reported by 10 of the N-9 and 5 of the placebo group. Colposcopy showed erythema in 9 of the N-9 group and 2 of the placebo group. Histologic inflammation was found in 7 of the N-9 group and 2 of the placebo group. Inflammatory changes were characterized by patchy infiltration of the lamina propria predominantly with CD8+ lymphocytes and macrophages, in the absence of epithelial disruption. A transient reduction in numbers of lactobacilli was observed in 9 of the 15 women using N-9, and 6 of 18 women using placebo. N-9 used for 7 days in a standard spermicidal dose was associated with increased irritation, colposcopic and histologic evidence of inflammation and was more frequently associated with reduction in numbers of lactobacilli during gel use. The clinical significance of the recruitment of cells susceptible to HIV infection to the genital mucosa is unknown but raises concerns about the suitability of N-9 as a microbicide when given in this dose.

Commentary: methods women can use that may prevent sexually transmitted disease, including HIV

Although sexually transmitted diseases, including human immunodeficiency virus (HIV), are a major concern for women, few prevention messages are targeted specifically to women. Those that are generally stress abstaining, altering the number or selection of partners, and urging partners to use condoms. But these behaviors may be unrealistic for many women, particularly women who are at highest risk for sexually transmitted diseases, because they require significant changes in life-style or depend on male-controlled condom use. Recommendation of contraceptives for prevention of sexually transmitted diseases depends largely on how well specific methods perform under controlled conditions, either in the laboratory or in clinical trials. Observational studies, which better reflect day-to-day use, indicate that condoms, barriers, and spermicides, used properly and consistently, can provide substantial protection against various sexually transmitted diseases. Condoms can similarly help protect against HIV, but studies of barriers and spermicides are scant and currently inconclusive. Finally, those methods that are controlled by women are consistently more effective in preventing sexually transmitted diseases. Thus, although condoms used well are still the best choice, the imperative for female-controlled methods indicates that diaphragms and spermicides should receive greater emphasis in prevention messages.

Barrier contraceptives and sexually transmitted diseases in women: a comparison of female-dependent methods and condoms

INTRODUCTION

Most efforts at sexually transmitted disease (STD) protection center on condom use, but little is known about how condoms compare with other barrier methods, particularly those controlled by women.

METHODS

To evaluate the effect of different barrier contraceptives on the prevalence of STDs and other vaginal infections, we retrospectively studied 5681 visits by women to an urban STD clinic.

RESULTS

As compared with women using no contraceptive or with tubal ligations, women using the contraceptive sponge or diaphragm had at least 65% lower rates of infection with Neisseria gonorrhoeae and Trichomonas vaginalis, while condom users had 34% and 30% lower rates, respectively. For Chlamydia trachomatis, the reduction was 13% among sponge users, 72% among diaphragm users, and 3% among condom users, although these differences were not significant. When compared with women using condoms, women using female-dependent methods (sponge or diaphragm) had significantly lower rates of both gonorrhea and trichomoniasis. Vaginal candidiasis was more common among women using diaphragms but not other barrier methods, while rates of bacterial vaginosis were similar among all groups.

CONCLUSIONS

Women using the contraceptive sponge or diaphragm experience protection from STDs to a greater extent than those relying on condoms. Female-dependent barrier contraceptives should receive more attention in STD risk-reduction programs.