People living with HIV are now living longer and more sexually active lives.1
Many individuals who test positive for HIV reduce or eliminate behaviors that can transmit HIV to others.2,3
However, these reductions are not absolute because individuals who reduce HIV risk behaviors may not maintain these practices for a lifetime. Several studies have demonstrated that approximately one-third of persons diagnosed with HIV infection may continue to engage in sexual practices.4
These behaviors place their HIV-negative sexual partners at risk of disease acquisition and themselves and other HIV-positive sexual partners at risk for exposure to infection with a different strain of HIV. Decreasing the number of unprotected sexual acts between individuals living with HIV and persons of unknown or HIV-negative status is the most targeted method of reducing sexual transmission of HIV.5
Therefore, evaluating the impact of a behavioral intervention for HIV-serodiscordant couples requires measuring sexual risk behaviors targeted by the intervention.
Historically, HIV prevention interventions have relied almost exclusively on individuals’ self-reported behavior change to assess intervention efficacy.6
Typical self-reported behaviors that have served as the cornerstone of assessing intervention efficacy include frequency of condom use, number of different sexual partners, or frequency of drug use when engaging in sexual behavior.6
EBAN trial investigators believe that using a measure of self-reported sexual behavior is crucial because it is the most frequently used behavioral outcome in HIV prevention trials. Additionally, the study assessed a set of theoretically derived mediating variables through which change in self-reported risky sexual behaviors is hypothesized to occur. However, for numerous reasons, trial investigators were cautious about relying entirely on the measurement of self-reported sexual behaviors to assess programmatic efficacy. First, several observational studies exploring the relationship between behavioral and biomedical outcomes have failed to show a strong relationship between individuals’ risk behaviors and sexually transmitted disease (STD) acquisition.7
Additionally, some HIV interventions have not observed a strong relationship between individuals’ sexual behaviors and STD acquisition.8
Furthermore, there is ample empirical evidence suggesting that self-report of sexual behavior may be subject to potential reporting biases, such as inaccurate recall bias (encoding, distortion, retrieval, and reconstruction)9–11
and social desirability bias.12,13
Over the past several decades, improvements in the formatting and framing of sexual behavior questions have enhanced the validity of self-reported sexual behaviors. Research shows that estimates of sexual behavior are more likely to be valid if surveys enquire about behaviors that occur during shorter recall periods.11,13
Use of cues, such as activities and important events, have also been beneficial.9,14,15
Additionally, the advent of audio computer-assisted self-interviewing (ACASI) has reduced barriers to literacy, minimized social desirability bias, and has been shown to yield higher rates of self-reported sexual behaviors than interviewer-administered or self-administered surveys.13,16
Even with these advances, assessment of sexually transmitted infections (STIs) has been advocated as a complementary measure for evaluating programmatic efficacy.17,18
Historically, the primary drawback of using biological markers, such as STDs, was the logistics of data collection. Data collection was typically feasible only in a clinical environment, such as a doctor’s office or an STD treatment center, and often required trained clinicians utilizing invasive procedures. Recently, however, major developments have been made in STD diagnostic procedures, in particular the introduction of DNA amplification assays that have high sensitivity and specificity. With the availability of these DNA amplification techniques that can identify bacterial STDs in urine specimens, in particular prevalent STDs such as chlamydia and gonorrhea, it is now possible to detect STDs in a noninvasive manner in a broad range of nonclinical settings.19–24
The development of this diagnostic technology paved the way for greater utilization of STDs as a clinical end point in evaluating HIV prevention interventions.
Furthermore, including STIs as an end point in HIV prevention trials recognizes the impact of STD on HIV transmission. Specifically, HIV-positive persons with an STD may be more likely to transmit HIV to others due to the effects of the STD on HIV infectivity, such as increased shedding of HIV. Furthermore, HIV-negative persons with an STD may be more susceptible to a subsequent exposure to HIV because the STD may compromise the mucosal or cutaneous surfaces of the genital tract that normally act as a barrier against HIV.25
The use of biological end points, while representing an objective and quantifiable marker of high-risk sexual behavior, is not without controversy nor is it a panacea for avoiding bias associated with self-report. It is important to recognize that reliance on incident STDs as a measure of program efficacy may not be an appropriate outcome for every study. It is unlikely, for instance, that the incidence of STDs will be changed in a short-term study conducted in a population with little sexual activity or in a community with a low prevalence of STDs.26
Conversely, populations with a high degree of sexual activity and a high prevalence of STDs are ideal for studying the effects of behavioral interventions on STD incidence. Moreover, studies incorporating biological markers as the primary outcome measure need to be conducted with samples that are sufficiently large and a follow-up of sufficient duration to provide adequate statistical power to detect differences in STD incidence.26
A review of randomized controlled trials of individual-level, population-level, and multilevel interventions for preventing STIs identified 41 trials that met inclusion criteria and used STD outcomes as objective measures of intervention efficacy.27
Among individual- and group-level interventions, 32 targeted acquisition, 4 targeted transmission, and 1 targeted complications of STIs. The most common intervention modality used was behavioral interventions; 11 of the 41 of the interventions were designed to reduce high-risk sexual practices. Notably, few of the studies in this review have been conducted among HIV-positive individuals.27
One trial was efficacious in reducing STDs among individuals living with HIV28
and another trial reported a reduction in STD symptoms in couples.29
There have not been any published HIV prevention trials conducted among African American serodiscordant couples using biological outcome markers as measures of efficacy. The EBAN trial investigators sought to use a primary biological outcome measure to complement the use of a behavioral outcome measure to assess intervention efficacy given the moderate degree of risky sexual behaviors,4
among individuals living with HIV; the experience of the EBAN trial investigators in using STDs to assess HIV intervention efficacy28,31
; the 12-month follow-up period to assess incident STD acquisition; the large study sample of African American couples (N = 536 couples); and the public health significance of reducing STD acquisition among African American HIV-serodiscordant couples.32
This article describes approaches used to minimize limitations in using self-reported sexual behavior and objective STD data as primary outcomes in an HIV/STD prevention program for African American serodiscordant couples (EBAN).
In this 2-armed randomized controlled trial, data collection for the primary behavioral outcome and the primary biological outcome was generated from 3 data sources over 4 assessment points. Specifically, data were collected from participants at the baseline, the immediate postintervention assessment, and the 6- and 12-month follow-up assessments. Urine and vaginal swabs were used to identify 3 STDs. ACASI was administered to assess the primary behavioral outcome, and the administration of ACASI in this trial is discussed in greater detail in the article Designing an Audio Computer Assisted Self Interview (ACASI) System in a Multisite Trial: A Brief Report. provides a description of the data collection modalities used in this trial.
Modes of Data Collection for the Primary Behavioral and Biological Outcome