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1.  HIV-1 subtype C is not associated with higher risk of heterosexual HIV-1 transmission: a multinational study among African HIV-1 serodiscordant couples 
AIDS (London, England)  2014;28(2):235-243.
HIV-1 subtype C has emerged as the most prevalent strain of HIV-1 worldwide, leading to speculation that subtype C may be more transmissible than other subtypes. We compared the risk of HIV-1 transmission for subtype C versus non-C subtypes (A, D, G and recombinant forms) among heterosexual African HIV-1 serodiscordant couples.
We conducted a nested case-control analysis using data from two prospective cohort studies of heterosexual HIV-1 serodiscordant couples from 6 countries in eastern and southern Africa. Cases (N=121) included incident HIV-1 transmissions that were established as linked within the serodiscordant partnership by viral sequencing; controls (N=501) were non-transmitting HIV-1 infected partners. Subtype was determined for partial env and gag genes. Multiple logistic regression controlled for age and gender of the HIV-1 infected partner and self-reported unprotected sex. Plasma and genital HIV-1 RNA concentrations were compared between subtype C and non-C subtypes using generalized estimating equations.
HIV-1 subtype C was not associated with increased risk of HIV-1 transmission compared to non-C subtypes: env adjusted odds ratio (adjOR) 1.14 (95% confidence interval [CI] 0.74–1.75, p=0.6) and gag adjOR 0.98 (95% CI 0.63–1.52, p=0.9). Plasma and genital HIV-1 RNA levels did not differ significantly for subtype C versus non-C.
In a geographically diverse population of heterosexual African HIV-1 serodiscordant couples, subtype C was not associated with greater risk of HIV-1 transmission compared to non-C subtypes, arguing against the hypothesis that subtype C is more transmissible compared to other common subtypes.
PMCID: PMC4090091  PMID: 24413311
HIV-1 subtype; transmission; serodiscordant couples; Africa
2.  High Incidence Is Not High Exposure: What Proportion of Prevention Trial Participants Are Exposed to HIV? 
PLoS ONE  2015;10(1):e0115528.
Randomized clinical trials of HIV prevention in high-risk populations of women often assume that all participants have similar exposure to HIV. However, a substantial fraction of women enrolled in the trial may have no or low exposure to HIV. Our objective was to estimate the proportion of women exposed to HIV throughout a hypothetical high-risk study population.
A stochastic individual-based model was developed to simulate the sexual behavior and the risk of HIV acquisition for a cohort of sexually active HIV-uninfected women in high HIV prevalence settings. Key behavior and epidemic assumptions in the model were based on published studies on HIV transmission in South Africa. The prevalence of exposure, defined as the proportion of women who have sex with HIV-infected partner, and HIV incidence were evaluated.
Our model projects that in communities with HIV incidence rate of 1 per 100 person years, only 5-6% of women are exposed to HIV annually while in communities with an HIV incidence of 5 per 100 person years 20-25% of women are exposed to HIV. Approximately 70% of the new infections are acquired from partners with asymptomatic HIV.
Mathematical models suggest that a high proportion of women enrolled in HIV prevention trials may be unexposed to HIV even when incidence rates are high. The relationship between HIV exposure and other risk factors should be carefully analyzed when future clinical trials are planned.
PMCID: PMC4287619  PMID: 25569838
3.  Supporting research sites in resource-limited settings: Challenges in implementing IT infrastructure 
As Information and Communication Technology infrastructure becomes more reliable, new methods of Electronic Data Capture (EDC), datamarts/Data warehouses, and mobile computing provide platforms for rapid coordination of international research projects and multisite studies. However, despite the increasing availability of internet connectivity and communication systems in remote regions of the world, there are still significant obstacles. Sites with poor infrastructure face serious challenges participating in modern clinical and basic research, particularly that relying on EDC and internet communication technologies. This report discusses our experiences in supporting research in resource-limited settings (RLS). We describe examples of the practical and ethical/regulatory challenges raised by use of these newer technologies for data collection in multisite clinical studies.
PMCID: PMC4195443  PMID: 24321986
Information technology (IT); research infrastructure; data management; electronic data capture (EDC); mHealth; mobile technology
4.  Long Term Follow-up of Children in the HIVNET 012 Perinatal HIV Prevention Trial: Five-Year Growth and Survival 
To describe five year growth, survival and long-term safety among children exposed to nevirapine or zidovudine in an African perinatal prevention trial, HIVNET 012.
All study children who were alive at eighteen months of age were eligible for an extended follow-up study. Children whose families consented were enrolled and evaluated every six months from 24 to 60 months. At each visit, history, physical exam and growth measures were taken. From these measurements Z scores based on World Health Organization (WHO) standards were computed. Serious adverse event data were collected. Data from the initial and extended follow-up cohorts were included in the analysis.
528 study children were alive at age 18 months, and 491 (426 HIV uninfected; 65 infected) were enrolled into the follow-up study. Both exposed but uninfected children and HIV infected children were substantially below WHO growth standards for weight and height. Head circumference Z scores for uninfected children were comparable to WHO norms. Five-year survival rates were 93% for uninfected children versus 43% for infected children. Long-term safety and growth outcomes in the two study arms were similar.
Both infected and uninfected children in the five-year HIVNET 012 follow-up showed poor height and weight growth outcomes, underscoring the need for early nutritional interventions to improve long-term growth of all infants born to HIV-infected women in resource limited settings. Likewise, the low five year survival among HIV infected children support the importance of early initiation of antiretroviral therapy. Both peripartum nevirapine and zidovudine were safe.
PMCID: PMC4172334  PMID: 24121753
5.  PrEP is Efficacious for HIV-1 prevention among Women using DMPA for Contraception 
AIDS (London, England)  2014;28(18):2771-2776.
To evaluate pre-exposure prophylaxis (PrEP) efficacy for HIV-1 prevention among women using depot medroxyprogesterone acetate (DMPA) for contraception and men whose HIV-1 infected partners use DMPA.
Secondary analysis of data from a randomized placebo-controlled trial of daily oral tenofovir and emtricitabine/tenofovir PrEP among heterosexual Kenyan and Ugandan HIV-1 serodiscordant couples
PrEP efficacy for HIV-1 prevention was compared among HIV-1 uninfected women using DMPA versus no hormonal contraception and among HIV-1 uninfected men whose HIV-1 infected female partners used DMPA versus no hormonal contraception.
Of 4747 HIV-1 serodiscordant couples, 901 HIV-1 uninfected women used DMPA at some point during follow-up, 1422 HIV-1 uninfected women used no hormonal contraception, 1568 HIV-1 uninfected men had female partners who used DMPA, and 2626 men had female partners who used no hormonal contraception. PrEP efficacy estimates for HIV-1 prevention, compared to placebo, were similar among women using DMPA and those using no hormonal contraception (64.7% and 75.5%, adjusted interaction p=0.65). Similarly, for men whose female partners used DMPA, PrEP efficacy did not differ from men whose partners used no hormonal contraception (90.0% versus 81.7%, adjusted interaction p=0.52).
PrEP is efficacious for HIV-1 prevention among women using DMPA and men whose partners use DMPA, suggesting PrEP could mitigate the potential increased HIV-1 acquisition and transmission risks that have been associated with DMPA use. Women at risk for HIV-1 choosing DMPA could maintain this contraceptive method and add PrEP to achieve prevention of unintended pregnancy and HIV-1.
PMCID: PMC4266161  PMID: 25493602
HIV-1 prevention; pre-exposure prophylaxis efficacy; hormonal contraception; DMPA
6.  Summary measures of adherence using pill counts in two HIV prevention trials: the need for standardisation in reporting 
AIDS and behavior  2013;17(9):10.1007/s10461-013-0542-9.
For trials of user-dependent HIV prevention products, accurate adherence measurements are essential to interpret and compare results across trials. We used pill count data from two recent HIV prevention trials of herpes simplex virus type 2 (HSV-2) suppression, to show that estimates of adherence vary substantially depending on assumptions that are made in analysing pill count data. We associate calculated adherence with biological markers of anti-HSV-2 activity. In both trials, calculated adherence varied considerably, depending on the summary measure used, and the handling of intervals with apparent ‘over-adherence’ (fewer pills returned than expected), and unreturned pills. Intervals of apparent over-adherence were associated with reduced antiviral effects on biological markers of herpes reactivation, indicating these are likely to represent periods of non-adherence. Our results demonstrate the clear need for standardisation in reporting of adherence data that are based on pill counts.
PMCID: PMC3812335  PMID: 23801018
Adherence; HIV prevention; pill counts
7.  Daily Short Message Service Surveys to Measure Sexual Behavior and Pre-exposure Prophylaxis Use Among Kenyan Men and Women 
AIDS and behavior  2013;17(9):10.1007/s10461-013-0510-4.
Pre-exposure prophylaxis (PrEP) is a novel HIV prevention strategy which requires high adherence. We tested the use of daily short message service (i.e., SMS/text message) surveys to measure sexual behavior and PrEP adherence in Kenya. Ninety-six HIV-uninfected adult individuals, taking daily oral PrEP in a clinical trial, received daily SMS surveys for 60 days. Most participants (96.9 %) reported taking PrEP on ≥80 % days, but 69.8 % missed at least one dose. Unprotected sex was reported on 4.9 % of days; however, 47.9 % of participants reported unprotected sex at least once. Unprotected sex was not correlated with PrEP use (OR = 0.95). Participants reporting more sex were less likely to report PrEP non-adherence and those reporting no sex were most likely to report missing a PrEP dose (adjusted OR = 1.87). PrEP adherence was high, missed doses were correlated with sexual abstinence, and unprotected sex was not associated with decreased PrEP adherence.
PMCID: PMC3812384  PMID: 23695519
HIV prevention; Pre-exposure prophylaxis; Sexual behavior; Adherence; HIV serodiscordant couples
8.  Differential Regulatory T Cell Activity in HIV Type 1-Exposed Seronegative Individuals 
AIDS Research and Human Retroviruses  2013;29(10):1321-1329.
The potential role of conventional and regulatory T cells (Tregs) in protection from HIV-1 infection remains unclear. To address this question, we analyzed samples from 129 HIV-1-exposed seronegative individuals (HESN) from an HIV-1-serodiscordant couples cohort. To assess the presence of HIV-specific T cell responses and Treg function, we measured the proliferation of T cells in response to HIV-1 peptide pools in peripheral blood mononuclear cells (PBMCs) and PBMCs depleted of Tregs. We identified HIV-specific CD4+ and CD8+ T cell responses and, surprisingly, the overall CD4+ and CD8+ T cell response rate was not increased when Tregs were removed from cell preparations. Of the 20 individuals that had HIV-1-specific CD4+ T cell responses, only eight had Tregs that could suppress this proliferation. When compared with individuals whose Tregs could suppress HIV-1-specific CD4+ T cell proliferation, individuals with Tregs unable to suppress showed a trend toward increased T cell activation and Treg frequency and a significant increase in HIV-1-specific production of microphage inflammatory protein-1β (MIP-1β) by CD4+ T cells, autocrine production of which has been shown to be protective in terms of HIV-1 infection of CD4+ T cells.
PMCID: PMC3785803  PMID: 23815575
9.  Anal Sex Role Segregation and Versatility among Men Who Have Sex with Men: EXPLORE Study 
Anal sex role patterns and correlates during unprotected anal sex were examined longitudinally among HIV-negative men who have sex with men (MSM). 9.6% were exclusively receptive, 16.7% exclusively insertive, and 63.0% versatile. Versatility was more likely with primary and HIV-negative/unknown status partners and among younger men and substance users, but less likely among Blacks and with higher number of partners. Exclusively receptive role was more likely with HIV-negative/unknown status partners and among younger men and substance users, but less likely with higher number of partners. Examining anal sex role patterns helps understand the factors that drive the epidemic among MSM.
PMCID: PMC3804162  PMID: 23945255
Role Segregation; Versatility; Anal Sex Role; men who have sex with men; HIV
10.  Efficacy of pre-exposure prophylaxis for HIV-1 prevention among high risk heterosexuals: subgroup analyses from the Partners PrEP Study 
AIDS (London, England)  2013;27(13):10.1097/QAD.0b013e3283629037.
Daily oral antiretroviral pre-exposure prophylaxis (PrEP) is a promising strategy for prevention of HIV-1 acquisition. Three clinical trials demonstrated PrEP efficacy; however, two PrEP trials among women did not find protection against HIV-1. One hypothesis proposed for these divergent results is that PrEP efficacy may be reduced in populations with higher HIV-1 incidence.
Using data from the Partners PrEP Study, a randomized, placebo-controlled trial of daily oral tenofovir (TDF) and emtricitabine/tenofovir (FTC/TDF) PrEP among heterosexual HIV-1 serodiscordant couples from Kenya and Uganda, we assessed PrEP efficacy among subgroups at higher risk for HIV-1 acquisition, including subgroups of women with high HIV-1 incidence.
The overall placebo arm HIV-1 incidence was 2.0 per 100 person-years. Among higher-risk subgroups, placebo arm HIV-1 incidence ranged from 3.9 to 6.6 per 100 person-years. In all subgroups, PrEP was protective against HIV-1 acquisition, with efficacy point estimates ranging from 64% to 84%. Among subgroups of women with placebo-arm HIV-1 incidence >5.0, efficacy estimates ranged from 64% to 84%. Monthly visit attendance for PrEP refills and tenofovir detection in plasma were high.
Among higher-risk subgroups in the Partners PrEP Study, including groups solely of higher-risk women, both TDF alone and combined FTC/TDF PrEP had consistently high efficacy for HIV-1 protection. PrEP, when used with high adherence, is a highly-effective prevention strategy for higher-risk heterosexuals. Prioritizing PrEP for persons at high risk of HIV-1 will maximize its prevention impact.
PMCID: PMC3882910  PMID: 24384592
antiretroviral agents; HIV-1 acquisition; primary prevention; women; Africa
11.  Effect of community-based voluntary counselling and testing on HIV incidence and social and behavioural outcomes (NIMH Project Accept; HPTN 043): a cluster-randomised trial 
The lancet global health  2014;2(5):e267-e277.
NIMH Project Accept (HPTN 043) was a cluster-randomized trial that tested whether a multicomponent, multi-level prevention strategy (community-based voluntary counselling and testing [CBVCT]) reduced HIV incidence compared to standard voluntary counselling and testing (SVCT).
Forty-eight communities were enrolled at five sites in South Africa, Tanzania, Zimbabwe, and Thailand. CBVCT was designed to make testing more accessible in communities, engage communities through outreach, and provide post-test support services. SVCT comprised standard VCT services established at existing facilities. Communities were randomized in matched pairs to 36 months of CBVCT or SVCT. Data were collected at baseline (n=14,567) and post-intervention (n=56,683) by cross-sectional random surveys of 18–32 year-old community residents. HIV incidence was estimated using a cross-sectional multi-assay algorithm. Thailand was excluded from incidence analyses due to low HIV prevalence.
The estimated incidence in the CBVCT was 1.52% vs. 1.81% in the SVCT with an estimated reduction in HIV incidence of 13·9% (relative risk [RR]=0·86; 95% confidence interval [CI]=0·725–1·023; p=0·08). Women older than 24 years had RR=0·70 (95% CI=0·54–0·90; p=0·009). CBVCT increased testing rates by 25% overall (95% CI=12%–39%; p=0·0003), by 45% among men and 15% among women. No overall effect on sexual risk behaviour was observed. However, among HIV-infected participants, CBVCT reduced the number of sexual partners by 8% (95% CI=1%–15%; p=0.03) and the proportion of multiple partnerships by 30% (95% CI=8%-46%; p=0.01). Social norms regarding HIV testing were improved in CBVCT communities.
The intervention was effective in increasing HIV testing, particularly among men, promoted positive social norms regarding testing, and reduced behavioural risk among HIV-infected participants. A modest reduction in HIV incidence was observed. This intervention focused primarily on HIV detection. Current and future studies that include strategies for HIV treatment and viral suppression should demonstrate further incidence reductions.
PMCID: PMC4131207  PMID: 25103167
HIV; incidence; Project Accept; Africa; HPTN 043
12.  Study Design Considerations for Evaluating Efficacy of Systemic Pre-Exposure Prophylaxis Interventions 
The development of interventions for systemic Pre-Exposure Prophylaxis (PrEP) faces several significant challenges following the US Food and Drug Administration’s (FDA) approval of Emtricitabine/Tenofovir (FTC/TDF) for HIV prevention. This development is particularly complex because of inconsistency of efficacy results of FTC/TDF PrEP trials for HIV prevention.
Possible designs for a PrEP Phase 3 efficacy trial are obtained by considering scenarios for potential experimental PrEP and control regimens, including consideration of placebo and active controls, longer acting PrEP and alternate dosing schedules.
Non-inferiority (NI) trials with hazard ratio NI margins ranging from 1.10 to 1.25 can be justified in the contexts of the three PrEP trials demonstrating efficacy of FTC/TDF. However these HIV endpoint trials may require extremely large numbers of participants, particularly in settings where FTC/TDF has been shown to reduce the risk of HIV acquisition. NI trials also are often difficult to interpret because they depend on prior placebo-controlled efficacy results. Superiority trials for PrEP are plausible in settings where FTC/TDF efficacy is not yet established, possibly due to low adherence (i.e. women at risk as in FemPrEP and VOICE): a new product with potential for higher adherence and potency would be a promising candidate in this setting.
Following FDA approval of FTC/TDF for PrEP, trials to establish efficacy of new PrEP regimens require stringent design standards, together with rigorous debate about adherence within study populations and many important ethical issues.
PMCID: PMC3725298  PMID: 23764624
Pre-exposure Prophylaxis; Non-inferiority; efficacy; phase 3; clinical trials; adherence
13.  Cross-Sectional HIV Incidence Estimation in HIV Prevention Research 
Accurate methods for estimating HIV incidence from cross-sectional samples would have great utility in prevention research. This report describes recent improvements in cross-sectional methods that significantly improve their accuracy. These improvements are based on the use of multiple biomarkers to identify recent HIV infections. These multi-assay algorithms (MAAs) use assays in a hierarchical approach for testing that minimizes the effort and cost of incidence estimation. These MAAs do not require mathematical adjustments for accurate estimation of the incidence rates in study populations in the year prior to sample collection. MAAs provide a practical, accurate, and cost-effective approach for cross-sectional HIV incidence estimation that can be used for HIV prevention research and global epidemic monitoring.
PMCID: PMC3737594  PMID: 23764641
HIV; incidence; cross-sectional; multi-assay algorithm
14.  The dynamic relationship between social norms and behaviors: The results of an HIV prevention network intervention for injection drug users 
Addiction (Abingdon, England)  2013;108(5):934-943.
Social norms are a key source of influence on health behaviors. This study examined changes in social norms and relationships between HIV injection risk behaviors and social norms among injection drug users (IDUs) involved in an experimental intervention.
Randomized clinical trial.
An HIV Prevention Trials Network study, Philadelphia, USA.
IDUs, called indexes, and their social network members, who were drug or sex partners, were recruited for an HIV prevention intervention and followed for up to 30 months (N=652). Indexes were randomized into a peer education intervention or control condition.
Outcomes of injection related HIV risk behaviors (sharing needles, sharing cookers, sharing cotton, front/back-loaded) were measured every 6 months and social norm of these 4 risk behaviors were assessed every 12 months.
There was a statistically significant intervention effect on all four social norms of injection behaviors, with participants in the intervention reporting less risky social norms compared with controls (changes in mean score: needles, -0.24, p.<01; cookers, -0.33, p.<01; cottons, -0.28, p.<05; front/back loading, -0.23, p.<01). There was also a statistically significant bidirectional association with social norms predicting injection risk behaviors at the next assessment and risk behaviors predicting social norms at the subsequent visit.
Through social network interventions it is feasible to change both injection risk behaviors and associated social norms. However, it is critical that social network interventions focus on publically highlighting behavior changes since changing social norms without awareness of behaviors change may lead to relapse of risk behaviors.
PMCID: PMC3628934  PMID: 23362861
15.  Prevalence and Seroincidence of Hepatitis B and Hepatitis C Infection in High Risk People Who Inject Drugs in China and Thailand 
We determined the prevalence and incidence of HBV and HCV infection in people who inject drugs (PWIDs) at high risk for HIV in China and Thailand and determined the association of HBV and HCV incidence with urine opiate test results and with short-term versus long-term buprenorphine-naloxone (B-N) treatment use in a randomized clinical trial (HPTN 058). 13.8% of 1049 PWIDs in China and 13.9% of 201 PWIDs in Thailand were HBsAg positive at baseline. Among HBsAg negative participants, the HBsAg incidence rate was 2.7/100 person years in China and 0/100 person years in Thailand. 81.9% of 1049 PWIDs in China and 59.7% of 201 in Thailand were HCV antibody positive at baseline. The HCV confirmed seroincidence rate among HCV antibody negative PWIDs was 22/100 person years in China and 4.6/100 person years in Thailand. Incident HBsAg was not significantly different in the short-term versus long-term B-N arm in China or Thailand. Participants with positive opiate results in at least 75% of their urines during the time period were at increased risk of incident HBsAg (HR = 5.22; 95% CI, 1.08 to 25.22; P = 0.04) in China, but not incident HCV conversion in China or Thailand.
PMCID: PMC3985324  PMID: 24860664
16.  Clinician Practices and Attitudes Regarding Early Antiretroviral Therapy in the US 
Use of antiretroviral therapy (ART) to prevent HIV transmission has received substantial attention following a recent trial demonstrating efficacy of ART to reduce HIV transmission in HIV-discordant couples.
To assess practices and attitudes of HIV clinicians regarding early initiation of ART for treatment and prevention of HIV at sites participating in the HPTN 065 study.
Cross-sectional internet-based survey.
ART-prescribing clinicians (n=165 physicians, nurse-practitioners, physician assistants) at 38 HIV care sites in Bronx, NY and Washington, DC completed a brief anonymous internet survey, prior to any participation in the HPTN 065 study. Analyses included associations between clinician characteristics and willingness to prescribe ART for prevention.
Almost all respondents (95%), of whom 59% were female, 66% white and 77% HIV specialists, “strongly agreed/agreed” that early ART can decrease HIV transmission. Fifty-six percent currently recommend ART initiation for HIV-infected patients with CD4+ count ≤500 cells/mm3, and 14 percent indicated that they initiate ART irrespective of CD4+ count. Most (75%) indicated that they would consider initiating ART earlier than otherwise indicated for patients in HIV-discordant sexual partnerships, and 40% would do so if a patient was having unprotected sex with a partner of unknown HIV status. There were no significant differences by age, gender, or clinician type in likelihood of initiating ART for reasons including HIV transmission prevention to sexual partners.
This sample of US clinicians indicated support for early ART initiation to prevent HIV transmission, especially for situations where such transmission would be more likely to occur.
PMCID: PMC3957230  PMID: 23183150
HIV prevention; early antiretroviral therapy; test and treat; clinician survey
17.  Sexual Behavior of Heterosexual Men and Women Receiving Antiretroviral Pre-Exposure Prophylaxis for HIV Prevention: A Longitudinal Analysis 
The Lancet infectious diseases  2013;13(12):1021-1028.
Limited data are available to assess sexual behavior by persons using antiretroviral pre-exposure prophylaxis (PrEP) for HIV prevention. Increased sexual risk taking by persons using effective HIV prevention strategies, like PrEP, could offset HIV prevention benefits.
The Partners PrEP Study, a randomized, placebo-controlled trial of daily oral PrEP among heterosexual HIV-uninfected members of HIV serodiscordant couples, publicly reported efficacy for HIV prevention in July 2011 and participants continued monthly follow-up thereafter. We used regression analyses to compare the frequency of sex unprotected by a condom during the 12 months after compared to before July 2011 to assess whether knowledge of PrEP efficacy for HIV prevention resulted in increased sexual risk behavior.
We analyzed 56, 132 person-months from 3024 HIV-uninfected subjects (64% male). The average frequency of unprotected sex with the HIV-infected study partner was 59 per 100 person-months pre- versus 53 post-unblinding, reflecting no immediate change or change over time after July 2011 (p=0·66 and 0·25, respectively). There was a statistically significant increase in unprotected sex with outside partners over time after July 2011 but the effect was modest (average of 6.8 unprotected sex acts per year versus 6.2 acts in a predicted counterfactual scenario had unblinding not occurred, p=0·04). Compared to pre-July 2011, there was no significant increase in incident sexually transmitted infections or pregnancy after July 2011.
The transition from a blinded, placebo-controlled efficacy trial to all participants aware they were receiving active, efficacious PrEP in the Partners PrEP Study provided a “natural experiment” to evaluate sexual risk compensation. PrEP, provided as part of a comprehensive prevention package, may not result in substantial changes in risk-taking sexual behavior for heterosexual couples.
PMCID: PMC3920826  PMID: 24139639
19.  HIV Incidence Determination in the United States: A Multiassay Approach 
The Journal of Infectious Diseases  2012;207(2):232-239.
Background. Accurate testing algorithms are needed for estimating human immunodeficiency virus (HIV) incidence from cross-sectional surveys.
Methods. We developed a multiassay algorithm (MAA) for HIV incidence that includes the BED capture enzyme immunoassay (BED-CEIA), an antibody avidity assay, HIV load, and CD4+ T-cell count. We analyzed 1782 samples from 709 individuals in the United States who had a known duration of HIV infection (range, 0 to >8 years). Logistic regression with cubic splines was used to compare the performance of the MAA to the BED-CEIA and to determine the window period of the MAA. We compared the annual incidence estimated with the MAA to the annual incidence based on HIV seroconversion in a longitudinal cohort.
Results. The MAA had a window period of 141 days (95% confidence interval [CI], 94–150) and a very low false-recent misclassification rate (only 0.4% of 1474 samples from subjects infected for >1 year were misclassified as indicative of recent infection). In a cohort study, annual incidence based on HIV seroconversion was 1.04% (95% CI, .70%–1.55%). The incidence estimate obtained using the MAA was essentially identical: 0.97% (95% CI, .51%–1.71%).
Conclusions. The MAA is as sensitive for detecting recent HIV infection as the BED-CEIA and has a very low rate of false-recent misclassification. It provides a powerful tool for cross-sectional HIV incidence determination.
PMCID: PMC3532826  PMID: 23129760
HIV; incidence testing; United States; epidemiology
20.  HPTN 071 (PopART): A Cluster-Randomized Trial of the Population Impact of an HIV Combination Prevention Intervention Including Universal Testing and Treatment: Mathematical Model 
PLoS ONE  2014;9(1):e84511.
The HPTN 052 trial confirmed that antiretroviral therapy (ART) can nearly eliminate HIV transmission from successfully treated HIV-infected individuals within couples. Here, we present the mathematical modeling used to inform the design and monitoring of a new trial aiming to test whether widespread provision of ART is feasible and can substantially reduce population-level HIV incidence.
Methods and Findings
The HPTN 071 (PopART) trial is a three-arm cluster-randomized trial of 21 large population clusters in Zambia and South Africa, starting in 2013. A combination prevention package including home-based voluntary testing and counseling, and ART for HIV positive individuals, will be delivered in arms A and B, with ART offered universally in arm A and according to national guidelines in arm B. Arm C will be the control arm. The primary endpoint is the cumulative three-year HIV incidence.
We developed a mathematical model of heterosexual HIV transmission, informed by recent data on HIV-1 natural history. We focused on realistically modeling the intervention package. Parameters were calibrated to data previously collected in these communities and national surveillance data.
We predict that, if targets are reached, HIV incidence over three years will drop by >60% in arm A and >25% in arm B, relative to arm C. The considerable uncertainty in the predicted reduction in incidence justifies the need for a trial. The main drivers of this uncertainty are possible community-level behavioral changes associated with the intervention, uptake of testing and treatment, as well as ART retention and adherence.
The HPTN 071 (PopART) trial intervention could reduce HIV population-level incidence by >60% over three years. This intervention could serve as a paradigm for national or supra-national implementation. Our analysis highlights the role mathematical modeling can play in trial development and monitoring, and more widely in evaluating the impact of treatment as prevention.
PMCID: PMC3893126  PMID: 24454728
21.  Development of Methods for Cross-Sectional HIV Incidence Estimation in a Large, Community Randomized Trial 
PLoS ONE  2013;8(11):e78818.
Accurate methods of HIV incidence determination are critically needed to monitor the epidemic and determine the population level impact of prevention trials. One such trial, Project Accept, a Phase III, community-randomized trial, evaluated the impact of enhanced, community-based voluntary counseling and testing on population-level HIV incidence. The primary endpoint of the trial was based on a single, cross-sectional, post-intervention HIV incidence assessment.
Methods and Findings
Test performance of HIV incidence determination was evaluated for 403 multi-assay algorithms [MAAs] that included the BED capture immunoassay [BED-CEIA] alone, an avidity assay alone, and combinations of these assays at different cutoff values with and without CD4 and viral load testing on samples from seven African cohorts (5,325 samples from 3,436 individuals with known duration of HIV infection [1 month to >10 years]). The mean window period (average time individuals appear positive for a given algorithm) and performance in estimating an incidence estimate (in terms of bias and variance) of these MAAs were evaluated in three simulated epidemic scenarios (stable, emerging and waning). The power of different test methods to detect a 35% reduction in incidence in the matched communities of Project Accept was also assessed. A MAA was identified that included BED-CEIA, the avidity assay, CD4 cell count, and viral load that had a window period of 259 days, accurately estimated HIV incidence in all three epidemic settings and provided sufficient power to detect an intervention effect in Project Accept.
In a Southern African setting, HIV incidence estimates and intervention effects can be accurately estimated from cross-sectional surveys using a MAA. The improved accuracy in cross-sectional incidence testing that a MAA provides is a powerful tool for HIV surveillance and program evaluation.
PMCID: PMC3827276  PMID: 24236054
22.  Statistical considerations for the HPTN 052 Study to evaluate the effectiveness of early versus delayed antiretroviral strategies to prevent the sexual transmission of HIV-1 in serodiscordant couples 
Contemporary clinical trials  2012;33(6):1280-1286.
The HIV Prevention Trial Network (HPTN) 052 Study is a Phase III, two-arm, controlled, open-labeled, randomized clinical trial designed to determine whether early antiretroviral therapy (ART) can prevent the sexual transmission of human immunodeficiency virus type 1 (HIV-1). A total of 1,763 couples in which one partner was HIV-1-positive and the other was HIV-1-negative were enrolled in four continents, nine countries and thirteen study sites. The HIV-1-positive partner was randomly assigned to either of the two arms: “immediate” (early) therapy with ART initiated upon enrollment plus HIV primary care, or “delayed” therapy with HIV primary care but ART initiated when the index case would have two consecutive measurements of a CD4+ cell count within or below the range of 200–250 cells/mm3, or develop an AIDS-defining illness. In this paper, we describe several key statistical considerations for the design of this landmark study. Despite that the observed event rates were lower than expected, which might have compromised the study power, an early release of the trial results in May 2011 showed an overwhelming 96% risk reduction for the immediate therapy in the prevention of genetically linked HIV-1 incident transmissions. Nevertheless, the durability of its long-term effectiveness is yet to be assessed. The HPTN 052 Study is still ongoing and will not complete till 2015.
PMCID: PMC3468650  PMID: 22813645
Antiretroviral therapy; Durability; Multinational; Partner; Treatment-as-prevention
23.  Use of a High Resolution Melting Assay to Analyze HIV Diversity in HIV-infected Ugandan Children 
We used a novel high resolution melting (HRM) diversity assay to analyze HIV diversity in Ugandan children (ages 0.6 to 12.4 years) who were enrolled in an observational study of antiretroviral treatment (ART). Children were maintained on ART if they were clinically and immunologically stable.
HIV diversity was measured prior to ART (baseline) in 76 children and after 48 or 96 weeks of ART in 14 children who were not virally suppressed. HIV diversity (expressed as HRM scores) was measured in six regions of the HIV genome (two in gag, one in pol, three in env).
Higher baseline HRM scores were significantly associated with older age (≥ 2 years, P ≤ 0.001 for all six regions). HRM scores from different regions were weakly correlated. Higher baseline HRM scores in three regions (one in gag, two in env) were associated with ART failure. HIV diversity was lower in four regions (two in gag, one in pol, one in env) after 48 to 96 weeks of non-suppressive ART compared to baseline.
Higher levels of HIV diversity were observed in older children prior to ART and higher levels of diversity in some regions of the HIV genome were associated with ART failure. Prolonged exposure to non-suppressive ART was associated with a significant decrease in viral diversity in selected regions of the HIV genome.
PMCID: PMC3473149  PMID: 22785048
HIV; diversity; children; antiretroviral therapy
24.  Quantifying Ongoing HIV-1 Exposure in HIV-1–Serodiscordant Couples to Identify Individuals With Potential Host Resistance to HIV-1 
The Journal of Infectious Diseases  2012;206(8):1299-1308.
Background. Immunogenetic correlates of resistance to HIV-1 in HIV-1–exposed seronegative (HESN) individuals with consistently high exposure may inform HIV-1 prevention strategies. We developed a novel approach for quantifying HIV-1 exposure to identify individuals remaining HIV-1 uninfected despite persistent high exposure.
Methods. We used longitudinal predictors of HIV-1 transmission in HIV-1 serodiscordant couples to score HIV-1 exposure and define HESN clusters with persistently high, low, and decreasing risk trajectories. The model was validated in an independent cohort of serodiscordant couples. We describe a statistical tool that can be applied to other HESN cohorts to identify individuals with high exposure to HIV-1.
Results. HIV-1 exposure was best quantified by frequency of unprotected sex with, plasma HIV-1 RNA levels among, and presence of genital ulcer disease among HIV-1–infected partners and by age, pregnancy status, herpes simplex virus 2 serostatus, and male circumcision status among HESN participants. Overall, 14% of HESN individuals persistently had high HIV-1 exposure and exhibited a declining incidence of HIV-1 infection over time.
Conclusions. A minority of HESN individuals from HIV-1–discordant couples had persistent high HIV-1 exposure over time. Decreasing incidence of infection in this group suggests these individuals were selected for resistance to HIV-1 and may be most appropriate for identifying biological correlates of natural host resistance to HIV-1 infection.
PMCID: PMC3448964  PMID: 22926009
25.  Recent Patterns in Population-Based HIV Prevalence in Swaziland 
PLoS ONE  2013;8(10):e77101.
The 2011 Swaziland HIV Incidence Measurement Survey (SHIMS) was conducted as part of a national study to evaluate the scale up of key HIV prevention programs.
From a randomly selected sample of all Swazi households, all women and men aged 18-49 were considered eligible, and all consenting adults were enrolled and received HIV testing and counseling. In this analysis, population-based measures of HIV prevalence were produced and compared against similarly measured HIV prevalence estimates from the 2006-7 Swaziland Demographic and Health. Also, measures of HIV service utilization in both HIV infected and uninfected populations were documented and discussed.
HIV prevalence among adults aged 18-49 has remained unchanged between 2006-2011 at 31-32%, with substantial differences in current prevalence between women (39%) and men (24%). In both men and women, between since 2006-7 and 2011, prevalence has fallen in the young age groups and risen in the older age groups. Over a third (38%) of the HIV-infected population was unaware of their infection status, and this differed markedly between men (50%) and women (31%). Of those aware of their HIV-positive status, a higher percentage of men (63%) than women (49%) reported ART use.
While overall HIV prevalence remains roughly constant, age-specific changes strongly suggest both improved survival of the HIV-infected and a reduction in new HIV infections. Awareness of HIV status and entry into ART services has improved in recent years but remains too low. This study identifies opportunities to improve both HIV preventive and care services in Swaziland.
PMCID: PMC3797108  PMID: 24143205

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