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Bannick M, Donnell D, Hayes R, Laeyendecker O, Gao F. An enhanced cross-sectional HIV incidence estimator that incorporates prior HIV test results. Stat Med 2024; 43:3125-3139. [PMID: 38803064 DOI: 10.1002/sim.10112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 02/14/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024]
Abstract
Incidence estimation of HIV infection can be performed using recent infection testing algorithm (RITA) results from a cross-sectional sample. This allows practitioners to understand population trends in the HIV epidemic without having to perform longitudinal follow-up on a cohort of individuals. The utility of the approach is limited by its precision, driven by the (low) sensitivity of the RITA at identifying recent infection. By utilizing results of previous HIV tests that individuals may have taken, we consider an enhanced RITA with increased sensitivity (and specificity). We use it to propose an enhanced estimator for incidence estimation. We prove the theoretical properties of the enhanced estimator and illustrate its numerical performance in simulation studies. We apply the estimator to data from a cluster-randomized trial to study the effect of community-level HIV interventions on HIV incidence. We demonstrate that the enhanced estimator provides a more precise estimate of HIV incidence compared to the standard estimator.
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Affiliation(s)
- Marlena Bannick
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Deborah Donnell
- Biostatistics, Bioinformatics and Epidemiology Program, Fred Hutchinson Cancer Center, Seattle, Washington, USA
- Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA
| | - Richard Hayes
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, England, UK
| | - Oliver Laeyendecker
- School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
- Division of Intramural Research, National Institute of Allergy and Infectious Diseases, Baltimore, Maryland, USA
| | - Fei Gao
- Biostatistics, Bioinformatics and Epidemiology Program, Fred Hutchinson Cancer Center, Seattle, Washington, USA
- Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA
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Donnell D, Kansiime S, Glidden DV, Luedtke A, Gilbert PB, Gao F, Janes H. Study design approaches for future active-controlled HIV prevention trials. STATISTICAL COMMUNICATIONS IN INFECTIOUS DISEASES 2024; 15:20230002. [PMID: 38250627 PMCID: PMC10798828 DOI: 10.1515/scid-2023-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/30/2023] [Indexed: 01/23/2024]
Abstract
Objectives Vigorous discussions are ongoing about future efficacy trial designs of candidate human immunodeficiency virus (HIV) prevention interventions. The study design challenges of HIV prevention interventions are considerable given rapid evolution of the prevention landscape and evidence of multiple modalities of highly effective products; future trials will likely be 'active-controlled', i.e., not include a placebo arm. Thus, novel design approaches are needed to accurately assess new interventions against these highly effective active controls. Methods To discuss active control design challenges and identify solutions, an initial virtual workshop series was hosted and supported by the International AIDS Enterprise (October 2020-March 2021). Subsequent symposia discussions continue to advance these efforts. As the non-inferiority design is an important conceptual reference design for guiding active control trials, we adopt several of its principles in our proposed design approaches. Results We discuss six potential study design approaches for formally evaluating absolute prevention efficacy given data from an active-controlled HIV prevention trial including using data from: 1) a registrational cohort, 2) recency assays, 3) an external trial placebo arm, 4) a biomarker of HIV incidence/exposure, 5) an anti-retroviral drug concentration as a mediator of prevention efficacy, and 6) immune biomarkers as a mediator of prevention efficacy. Conclusions Our understanding of these proposed novel approaches to future trial designs remains incomplete and there are many future statistical research needs. Yet, each of these approaches, within the context of an active-controlled trial, have the potential to yield reliable evidence of efficacy for future biomedical interventions.
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Affiliation(s)
- Deborah Donnell
- Fred Hutchinson Cancer Center, Seattle, WA, USA
- University of Washington, Seattle, WA, USA
| | - Sheila Kansiime
- Medical Research Council/Uganda Virus Research Council and London School of Hygiene and Tropical Medicine, Uganda Research Unit, Entebbe, Uganda
- Medical Research Council International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | | | | | - Peter B. Gilbert
- Fred Hutchinson Cancer Center, Seattle, WA, USA
- University of Washington, Seattle, WA, USA
| | - Fei Gao
- Fred Hutchinson Cancer Center, Seattle, WA, USA
- University of Washington, Seattle, WA, USA
| | - Holly Janes
- Fred Hutchinson Cancer Center, Seattle, WA, USA
- University of Washington, Seattle, WA, USA
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Moore M, Stansfield S, Donnell DJ, Boily MC, Mitchell KM, Anderson PL, Delany-Moretlwe S, Bekker LG, Mgodi NM, Celum CL, Dimitrov D. Efficacy estimates of oral pre-exposure prophylaxis for HIV prevention in cisgender women with partial adherence. Nat Med 2023; 29:2748-2752. [PMID: 37798438 DOI: 10.1038/s41591-023-02564-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 08/23/2023] [Indexed: 10/07/2023]
Abstract
Pre-exposure prophylaxis (PrEP) with tenofovir (TFV) disoproxil fumarate and emtricitabine administered orally daily is effective in preventing human immunodeficiency virus (HIV) acquisition in both men and women with sufficient adherence; however, the adherence-efficacy relationship in cisgender women has not been well established. We calculated the adherence-efficacy curve for cisgender women by using HIV incidence and plasma TFV concentration data from three trials (FEM-PrEP, VOICE and Partners PrEP). We imputed TFV diphosphate (TFV-DP) concentrations, a measure of long-term adherence, from TFV quantification by using data from the HIV Prevention Trials Network 082 study, which measured both TFV-DP and TFV concentrations. Two, four and seven pills per week reduced HIV incidence by 59.3% (95% credible interval (CrI) 29.9-95.8%), 83.8% (95% CI 51.7-99.8%) and 95.9% (95% CI 72.6-100%), respectively. Our adherence-efficacy curve can be validated and updated by HIV prevention studies that directly measure TFV-DP concentrations. The curve suggests that high adherence confers high protection in cisgender women. However, the lower efficacy with partial adherence highlights the need for new PrEP products and interventions to increase adherence.
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Affiliation(s)
- Mia Moore
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA.
- HPTN Modelling Centre, Imperial College London, London, UK.
| | - Sarah Stansfield
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- HPTN Modelling Centre, Imperial College London, London, UK
| | - Deborah J Donnell
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Marie-Claude Boily
- HPTN Modelling Centre, Imperial College London, London, UK
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Kate M Mitchell
- HPTN Modelling Centre, Imperial College London, London, UK
- Medical Research Council Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Peter L Anderson
- Anschutz Medical Campus, University of Colorado, Aurora, CO, USA
| | | | - Linda-Gail Bekker
- Desmond Tutu HIV Centre, University of Cape Town, Cape Town, South Africa
| | - Nyaradzo M Mgodi
- College of Health Sciences Clinical Trials Research Centre, University of Zimbabwe, Harare, Zimbabwe
| | - Connie L Celum
- Departments of Global Health, Medicine and Epidemiology, University of Washington, Seattle, WA, USA
| | - Dobromir Dimitrov
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- HPTN Modelling Centre, Imperial College London, London, UK
- Department of Applied Mathematics, University of Washington, Seattle, WA, USA
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Dunn DT, Stirrup OT, McCormack S, Glidden DV. Interpretation of active-control randomised trials: the case for a new analytical perspective involving averted events. BMC Med Res Methodol 2023; 23:149. [PMID: 37365584 DOI: 10.1186/s12874-023-01970-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 06/09/2023] [Indexed: 06/28/2023] Open
Abstract
Active-control trials, where an experimental treatment is compared with an established treatment, are performed when the inclusion of a placebo control group is deemed to be unethical. For time-to-event outcomes, the primary estimand is usually the rate ratio, or the closely-related hazard ratio, comparing the experimental group with the control group. In this article we describe major problems in the interpretation of this estimand, using examples from COVID-19 vaccine and HIV pre-exposure prophylaxis trials. In particular, when the control treatment is highly effective, the rate ratio may indicate that the experimental treatment is clearly statistically inferior even when it is worthwhile from a public health perspective. We argue that it is crucially important to consider averted events as well as observed events in the interpretation of active-control trials. An alternative metric that incorporates this information, the averted events ratio, is proposed and exemplified. Its interpretation is simple and conceptually appealing, namely the proportion of events that would be averted by using the experimental treatment rather than the control treatment. The averted events ratio cannot be directly estimated from the active-control trial, and requires an additional assumption about either: (a) the incidence that would have been observed in a hypothetical placebo arm (the counterfactual incidence) or (b) the efficacy of the control treatment (relative to no treatment) that pertained in the active-control trial. Although estimation of these parameters is not straightforward, this must be attempted in order to draw rational inferences. To date, this method has been applied only within HIV prevention research, but has wider applicability to treatment trials and other disease areas.
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Affiliation(s)
- David T Dunn
- Institute for Global Health, University College London, London, UK.
- MRC Clinical Trials Unit, University College London, 90 High Holborn, London, WC1V 6LJ, UK.
| | - Oliver T Stirrup
- Institute for Global Health, University College London, London, UK
| | - Sheena McCormack
- MRC Clinical Trials Unit, University College London, 90 High Holborn, London, WC1V 6LJ, UK
| | - David V Glidden
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA
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Parkin N, Gao F, Grebe E, Cutrell A, Das M, Donnell D, Duerr A, Glidden DV, Hughes JP, Murray J, Robertson MN, Zinserling J, Lau J, Miller V. Facilitating Next-Generation Pre-Exposure Prophylaxis Clinical Trials Using HIV Recent Infection Assays: A Consensus Statement from the Forum HIV Prevention Trial Design Project. Clin Pharmacol Ther 2022. [PMID: 36550769 DOI: 10.1002/cpt.2830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022]
Abstract
Standard-of-care HIV pre-exposure prophylaxis (PrEP) is highly efficacious, but uptake of and persistence on a daily oral pill is low in many settings. Evaluation of alternate PrEP products will require innovation to avoid the unpractically large sample sizes in noninferiority trials. We propose estimating HIV incidence in people not on PrEP as an external counterfactual to which on-PrEP incidence in trial subjects can be compared. HIV recent infection testing algorithms (RITAs), such as the limiting antigen avidity assay plus viral load used on specimens from untreated HIV positive people identified during screening, is one possible approach. Its feasibility is partly dependent on the sample size needed to ensure adequate power, which is impacted by RITA performance, the number of recent infections identified, the expected efficacy of the intervention, and other factors. Screening sample sizes to support detection of an 80% reduction in incidence for 3 key populations are more modest, and comparable to the number of participants in recent phase III PrEP trials. Sample sizes would be significantly larger in populations with lower incidence, where the false recency rate is higher or if PrEP efficacy is expected to be lower. Our proposed counterfactual approach appears to be feasible, offers high statistical power, and is nearly contemporaneous with the on-PrEP population. It will be important to monitor the performance of this approach during new product development for HIV prevention. If successful, it could be a model for preventive HIV vaccines and prevention of other infectious diseases.
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Affiliation(s)
- Neil Parkin
- Data First Consulting, Sebastopol, California, USA
| | - Fei Gao
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Eduard Grebe
- Vitalant Research Institute, San Francisco, California, USA.,Edward Grebe Consulting, Cape Town, South Africa
| | - Amy Cutrell
- ViiV Healthcare, Research Triangle Park, North Carolina, USA
| | - Moupali Das
- Gilead Sciences, Foster City, California, USA
| | - Deborah Donnell
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Ann Duerr
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | | | | | | | | | - Joerg Zinserling
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Bonn, Germany
| | - Joseph Lau
- Forum for Collaborative Research, Washington, DC, USA
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