The protocol for this trial and supporting CONSORT checklist are available as supporting information; see Checklist S1
and Protocol S1
We conducted this randomized, double-blind, placebo-controlled trial between January 2004 and March 2006 in Accra and Kumasi, Ghana. We enrolled HIV-antibody negative, non-pregnant women 18 to 35 years old who were at risk of HIV infection because of having a mean of three or more coital acts per week and two or more sexual partners in the 3 months before screening. Study participants were recruited from areas within each city that were considered high HIV transmission areas, including markets, bars, and hotels. Although we did not specifically ask as part of the clinical trial procedures if the participants were sex workers, most exchanged sex for money. Special ethical considerations were taken into account because of the potential vulnerability of this population. We included women who agreed to: use study gel as directed and follow study procedures; report self-medication with antibiotics during study participation; and avoid use spermicides or other vaginal contraceptives or lubricants during the study. We excluded women who: were intending pregnancy; had a history of latex allergy; were injection drug users; or had gynecological conditions that could affect the safety or effectiveness of the study gel.
We developed strategies to protect the confidentiality and autonomy of the participants, increase/ensure comprehension of the informed consent and research methods, and promote access to resources and services during and after the trial. The study protocol and informed consent forms were approved by 1) the Committee on Human Research, Publications and Ethics, School of Medical Sciences, University of Science & Technology, Kumasi, Ghana, 2) Noguchi Memorial Institute for Medical Research IRB, University of Ghana, Legon, Ghana, and 3) the Protection of Human Subjects Committee, Family Health International, USA. All participants provided written informed consent in their preferred language. Illiterate participants were read the informed consent forms verbatim in the presence of a witness, and provided a mark or thumbprint in lieu of signature.
During recruitment, study staff explained the general purpose of the study and the eligibility requirements. If eligible, women were referred to one of two study clinics in Kumasi or Accra. At the screening visit, women were interviewed to confirm understanding and willingness to comply with study requirements, completed written informed consent, received HIV pretest and condom counseling, and underwent oral mucosal transudate (OMT) rapid HIV testing. All participants received HIV post-test counseling, physical and pelvic examinations (including vaginal wet mount to support the diagnosis for bacterial vaginosis, trichomoniasis, or vaginal candidiasis), urine pregnancy tests, and STI (syphilis, gonorrhea, and chlamydia) tests. Women with reactive OMT rapid HIV tests received ELISA to confirm HIV status. We asked potential participants to return 4 weeks after their screening visit to receive the results of their STI and confirmatory HIV tests, if applicable.
At this second visit, participants received a detailed explanation of study procedures, signed or marked a consent form for enrollment, received HIV counseling, provided urine for pregnancy testing, provided another OMT sample for HIV testing, and if eligible were randomized to receive either SAVVY or placebo. Study staff gave each eligible participant her first month's supply of study product after she had been randomized. Clinic staff counseled participants to use the gel vaginally before each act of sexual intercourse (and to insert a second dose if more than one hour had elapsed between the first application and sexual intercourse), emphasized that the gel had unknown effectiveness for preventing HIV, distributed condoms, and counseled participants to use condoms for all sexual contacts with all partners. The informed consent form stated that: “We do not know the effects and safety of the gel during pregnancy. Pregnant women may not join this study. If you become pregnant during the study you should tell your study doctor or nurse right away. Your study gel will be stopped and the study doctor will discuss your choices with you.”
At each monthly follow-up visit, participants underwent OMT HIV and pregnancy testing, AE assessment, STI risk reduction counseling, and study product and condom re-supply. Participants responded to structured questionnaires on their interval sexual behavior (including coital activity, and gel and condom use), experience using the gel, and were reminded of study concepts discussed during the informed consent process. If clinically indicated, participants underwent physical examination and STI testing. Study staff documented whether product use was interrupted temporarily or permanently for any of the following reasons: participant ran out of supplies, investigator withdrew study product in the interest of the safety and well being of the participant, positive pregnancy test result, or confirmed HIV infection. Pregnant women were allowed to resume study product use after pregnancies had ended. Study staff referred participants infected with HIV during the study to local HIV-related psychological, social, and medical services (such as viral load, CD4 level, and HIV resistance testing) as well as antiretroviral drug therapy when needed. If a participant missed a scheduled follow-up appointment, study staff made up to 3 attempts to contact that participant and reschedule the appointment (ideally to occur within 2 weeks of the original appointment). If the participant could not be located after 3 attempts, no further efforts were made to find her, but her file remained open until study closeout. If the participant did not return to the study before the study was closed, she was considered lost to follow-up. The “lost to follow-up” designation was not made for any participant until the closing date of the study.
The objective of this trial was to determine the effectiveness of 1.0% C31G in preventing male-to-female vaginal transmission of HIV infection among women at high risk.
The primary measure of effectiveness was infection with HIV-1 or HIV-2, measured by detecting antibodies in oral mucosal transudate (OMT) (OraQuick® ADVANCE Rapid HIV-1/2 Antibody Test, Orasure Technologies) and confirmed by an enzyme-linked immunosorbent assay (ELISA) (Genetic Systems™ HIV-1/HIV-2 Plus O ELISA from BioRad) and/or Western Blot (Genetic Systems™ HIV-1 Western Blot, BioRad) from a finger prick or serum specimen. We evaluated safety by comparing the incidence of adverse events (AEs) including pelvic exam findings and sexually transmitted infections (STIs).
We estimated that a sample size of 2142 participants (1,071 in each treatment group) would give us 80% power to detect a 50% difference in the HIV infection rate (two-sided log-rank test, α
0.05 significance level) between the two groups. We assumed the rate of HIV infection in the control group to be 5/100 person-years and loss to follow-up to be 20%; approximately 66 total HIV infections were needed to achieve the desired power. Our protocol included plans for assessing (in a blinded manner) whether additional participants would be needed to observe the required 66 events.
Randomization and Blinding
We randomized enrolled participants into either the SAVVY or placebo arm using a 1
1 allocation ratio. A statistician not otherwise involved with the study developed the allocation sequence using a computer random number generator and randomly varied permuted-blocks of 12, 18, and 24. Six label colors (three SAVVY and three placebo) were used to differentiate the otherwise identically packaged gels. Randomization was stratified by study site. We used sequentially numbered, sealed opaque envelopes to assign participants to one of six color groups after they had qualified for the study and signed the consent form. The randomization envelopes were maintained in a secure office and were not available to study staff until the moment of randomization. Each randomization envelope was used only once. Participants, field study staff, monitors, statisticians, and other FHI staff involved in the trial were not aware of which gel colors were associated with SAVVY or placebo. Both SAVVY and placebo gels were clear, with similar viscosity and pH, dispensed in 3.5 mL doses with identical applicators.
The placebo gel was formulated to minimize any possible effects—negative or positive—on study endpoints. It was isotonic to avoid epithelial cell swelling or dehydration, and formulated at a pH of 4.4 but with minimal buffering capacity. When mixed with an equal volume of semen, the placebo gel induced only a trivial decrease in semen pH (from 7.8 to 7.7). The placebo gel contained hydroxyethylcellulose as a gelling agent, and its viscosity was comparable to that of SAVVY. Hydroxyethylcellulose does not have anti-HIV properties. The gel also contained sorbic acid as a preservative; sorbic acid has no anti-HIV activity and is readily metabolized by human cells.
For the primary effectiveness analysis we compared the probability of HIV infection for the SAVVY and placebo gel groups using a two-sided site-stratified, exact log-rank test (StatXact). We calculated Kaplan-Meier estimates of HIV infection probabilities by treatment group, pooled across sites. We used a proportional hazards regression model to estimate the hazard ratio, along with a 95% confidence interval, comparing the SAVVY group to the placebo group for HIV incidence, controlling for site. Each HIV infection onset date was estimated as the midpoint between the date of the first positive test result and the previous, negative test date. A right censoring time of 380 days was applied. Because the trial was terminated well before reaching the number of HIV infections targeted for pre-planned tests of effectiveness (i.e., before any of the type I error was to be spent), p-values for analyses of effectiveness should be interpreted as descriptive statistics. We calculated exact 95% confidence intervals for the relative risk of pre-specified priority AEs within system organ classes under a Poisson assumption for the event rates in each treatment group (StatXact). We compared proportions of women with any pelvic exam findings or STDs between treatment groups with a two-sided Mantel-Haenszel Chi-Square Test stratified by site at the 0.05 significance level.
All primary and most secondary analyses were either conducted on the Effectiveness Population which is the subset of the Intent-to-Treat (ITT) Population for whom at least one post-enrollment HIV evaluation is available, or the Safety Population which is the subset of the ITT Population who ever returned after enrollment. The Evaluable Population includes the same participants as the Effectiveness Population but excludes all data collected from a participant after her first documented interruption of product use.
Our data monitoring plan specified that the independent Data Monitoring Committee (DMC), with access to treatment assignments, would review AEs and primary safety and HIV seroconversion data twice, after approximately 16 and 33 events, respectively. However, testing for early evidence of effectiveness was scheduled only to occur at the second of these two planned looks and later when the target total number of events (66) was obtained (i.e., the first look at the HIV seroconversion data was to review the data for signs of harm) .
Monitors (trained in Good Clinical Practice) visited sites regularly to review study eligibility, informed consent, protocol compliance, laboratory procedures, source documents, product accountability, and AEs. We attempted to get original hospital records, when available, for serious adverse events (SAEs) and deaths.