Economic modeling of HIV treatments:

Improving the Youth HIV Prevention and Care Cascades: Innovative Designs in the Adolescent Trials Network for HIV/AIDS Interventions

Dramatic decreases in HIV transmission are achievable with currently available biomedical and behavioral interventions, including antiretroviral therapy and pre-exposure prophylaxis. However, such decreases have not yet been realized among adolescents and young adults. The Adolescent Medicine Trials Network (ATN) for HIV/AIDS interventions is dedicated to research addressing the needs of youth at high risk for HIV acquisition as well as youth living with HIV. This article provides an overview of an array of efficient and effective designs across the translational spectrum that are utilized within the ATN. These designs maximize methodological rigor and real-world applicability of findings while minimizing resource use. Implementation science and cost-effectiveness methods are included. Utilizing protocol examples, we demonstrate the feasibility of such designs to balance rigor and relevance to shorten the science-to-practice gap and improve the youth HIV prevention and care continua.

Clinic-Based Delivery of the Young Men's Health Project (YMHP) Targeting HIV Risk Reduction and Substance Use Among Young Men Who Have Sex with Men: Protocol for a Type 2, Hybrid Implementation-Effectiveness Trial

BACKGROUND

Young men who have sex with men (YMSM) are disproportionately at risk for HIV and sexually transmitted infections. Adapting and testing the effectiveness of the Young Men's Health Project (YMHP), an efficacious intervention designed to reduce substance use and condomless anal sex (CAS) among YMSM, at clinics in Miami, Detroit, and Philadelphia has the potential to reduce HIV and STI disparities among urban YMSM.

OBJECTIVE

This study (Adolescent Medicine Trials Network for HIV/AIDS Interventions [ATN] 145 YMHP) aims to adapt YMHP for clinic and remote delivery by existing clinic staff and compare their effectiveness in real-world adolescent HIV clinics. This protocol is part of the ATN Scale It Up program described in a recently published article by Naar et al.

METHODS

This is a comparative effectiveness hybrid type-2 trial of the YMHP intervention with 2 delivery formats-clinic-based versus remote delivery-offered following HIV counseling and testing. Phase 1 includes conducting focus groups with youth to obtain implementation feedback about the delivery of the YMHP intervention and intervention components to ensure culturally competent, feasible, and scalable implementation. Phase 2 includes recruitment and enrollment of 270 YMSM, aged 15 to 24 years, 90 at each of the 3 sites. Enrollment will be limited to HIV-negative YMSM who report recent substance use and either CAS or a positive STI test result. Participants will be randomized to receive the YMHP intervention either in person or by remote delivery. Both conditions involve completion of the 4 YMHP sessions and the delivery of pre-exposure prophylaxis information and navigation services. A minimum of 2 community health workers (CHWs) will be trained to deliver the intervention sessions at each site. Sessions will be audio-recorded for Motivational Interviewing Treatment Integrity (MITI) fidelity coding, and CHWs and supervisors will be given implementation support throughout the study period.

RESULTS

Phase 1 focus groups were completed in July 2017 (n=25). Feedback from these focus groups at the 3 sites informed adaptations to the YMHP intervention manual, implementation of the intervention, and recruitment plans for phase 2. Baseline enrollment for phase 2 began in November 2018, and assessments will be at immediate posttest (IP)-, 3-, 6-, 9-, and 12-months after the intervention. Upon collection of both baseline and follow-up data, we will compare the effectiveness and cost-effectiveness of clinic-based versus remote delivery of YMHP in the context of health care access.

CONCLUSIONS

We are conducting YMHP in 3 cities with high rates of YMSM at risk for HIV and STIs. When adapted for real-world clinics, this study will help substance-using YMSM at risk for HIV and STIs and allow us to examine differences in effectiveness and cost by the method of delivery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03488914; https://clinicaltrials.gov/ct2/show/NCT03488914 (Archived by WebCite at http://www.webcitation.org/770WaWWfi).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/11184.

Cost and cost-effectiveness of transitioning to universal initiation of lifelong antiretroviral therapy for all HIV-positive pregnant and breastfeeding women in Swaziland

OBJECTIVES

To assess the costs and cost-effectiveness of transitioning from antiretroviral therapy (ART) initiation based on CD4 cell count and WHO clinical staging ('Option A') to universal ART ('Option B+') for all HIV-infected pregnant and breastfeeding women in Swaziland.

METHODS

We measured the total costs of prevention of mother-to-child HIV transmission (PMTCT) service delivery at public sector facilities with empirical cost data collected at three points in time: once under Option A and again twice after transition to the Option B+ approach. The cost per woman treated per month includes recurrent costs (personnel, overheads, medication and diagnostic tests) and capital costs (buildings, furniture, start-up costs and training). Cost-effectiveness was estimated from the health services perspective as the cost per woman retained in care through 6 months postpartum. This analysis is nested within a larger stepped-wedge evaluation, which demonstrated a 26% increase in maternal retention after the transition to Option B+.

RESULTS

Across the five sites, the total cost for PMTCT during the study period (from August 2013 to October 2015, in 2015 US$) was $868,426 for Option B+ and $680 508 for Option A. The cost per woman treated per month was $183 for a woman on ART under Option B+, and $127 and $118 for a woman on ART and zidovudine (AZT), respectively, under Option A. The weighted average cost per woman treated on Option B+ was $826 compared to $525 under Option A. The main cost drivers were the start-up costs, additional training provided and staff time spent on PMTCT tasks for Option B+. The incremental cost-effectiveness ratio was estimated at $912 for every additional mother retained in care through six months postpartum.

CONCLUSIONS

The cost and cost-effectiveness outcomes from this study indicate that there is a robust economic case for pursuing the Option B+ approach in Swaziland and similar settings such as South Africa. Furthermore, these costs can be used to aid decision making and budgeting, for similar settings transitioning to test and treat strategy.

Cost effectiveness of darunavir/ritonavir combination antiretroviral therapy for treatment-naive adults with HIV-1 infection in Canada

OBJECTIVE

The AntiRetroviral Therapy with TMC114 ExaMined In naive Subjects (ARTEMIS) clinical trial examined the efficacy and safety of two ritonavir-boosted protease inhibitors (PI/r), darunavir/r 800/100 mg once daily (QD) and lopinavir/r 800/200 mg daily, both used in combination with tenofovir disoproxil fumarate/emtricitabine. This study aimed to assess the cost effectiveness of the darunavir/r regimen compared with the lopinavir/r regimen in treatment-naive adults with HIV-1 infection in Canada.

METHODS

A Markov model with a 3-month cycle time and six CD4 cell-count-based health states (>500, 351-500, 201-500, 101-200, 51-100, and 0-50 cells/mm(3)) followed a cohort of treatment-naive adults with HIV-1 infection through initial darunavir/r or lopinavir/r combination therapy and a common set of subsequent regimens over the course of their remaining lifetimes. Population characteristics and transition probabilities were estimated from the ARTEMIS clinical trial and other trials. Costs (in 2014 Canadian dollars), utilities, and mortality were estimated from Canadian sources and published literature. Costs and health outcomes were discounted at 5% per year. One-way and probabilistic sensitivity analyses were performed, including a simple indirect comparison of the darunavir/r initial regimen with an atazanavir/r-based regimen.

RESULTS

In the base-case lifetime analysis, individuals receiving initial therapy with the darunavir/r regimen experienced 0.25 more quality-adjusted life-years (QALYs) with lower antiretroviral drug costs (-$14,246) and total costs (-$18,402) than individuals receiving the lopinavir/r regimen, indicating that darunavir/r dominated lopinavir/r. In an indirect comparison with an atazanavir/r-based regimen, the darunavir/r regimen remained the dominant choice, but with lower cost savings (-$2,303) and QALY gains (0.02). Results were robust to a wide range of other changes in input parameter values, population characteristics, and modeling assumptions. The probabilistic sensitivity analysis demonstrated that the darunavir/r regimen was cost effective compared with the lopinavir/r regimen in over 86% of simulations for willingness-to-pay thresholds between $0 and $100,000 per QALY gained.

CONCLUSIONS

Darunavir/r 800/100 mg QD may be a cost-effective PI/r component of initial antiretroviral therapy for treatment-naive adults with HIV-1 infection in Canada.

A methodological review of models used to estimate the cost effectiveness of antiretroviral regimens for the treatment of HIV infection

The aim of this article was to perform a detailed methodological review of models used to estimate the cost effectiveness of drug treatment regimens for HIV infection in Europe and North America and assess the relationship between the different modeling approaches or key structural assumptions and the results. Electronic searches in three databases (MEDLINE, EMBASE, and the Cochrane Library) identified the cost-effectiveness models. Modeling approaches and structural assumptions were abstracted for all models. For three case studies of multiple analyses that compared the cost effectiveness of two drug regimens using the same clinical data inputs, differences in results were compared with differences in modeling approaches and structural assumptions. Forty-one model publications were reviewed. Recent models included Monte Carlo simulations, Markov models, or discrete-event simulation models, all including multiple lines of therapy and capturing the long-expected duration of efficacy of highly active antiretroviral therapy. In the three case studies, assumptions about the duration of efficacy after the trial time period, whether differences between the two regimens persist after the trial time period, the sequence of regimens after initial regimen failure, and the cost and utility assigned to adverse events, but not the modeling approach, were the most important factors in explaining differences in the results. As the models and treatment pathways get more complex, models should be validated using clinical trial data and local observational databases. The results of sensitivity analyses testing the impact of the structural assumptions that might change the results as identified in this review should also be presented in modeling papers.

Lopinavir/ritonavir versus darunavir plus ritonavir for HIV infection: a cost-effectiveness analysis for the United States

BACKGROUND

The ARTEMIS trial compared first-line antiretroviral therapy (ART) with lopinavir/ritonavir (LPV/r) to darunavir plus ritonavir (DRV + RTV) for HIV-1-infected subjects. In order to fully assess the implications of this study, economic modelling extrapolating over a longer term is required.

OBJECTIVE

The aim of this study was to simulate the course of HIV and its management, including the multiple factors known to be of importance in ART.

METHODS

A comprehensive discrete event simulation was created to represent, as realistically as possible, ART management and HIV outcomes. The model was focused on patients for whom clinicians believed that LPV/r or DRV + RTV were good options as a first regimen. Prognosis was determined by the impact of initial treatment on baseline CD4+ T-cell count and viral load, adherence, virological suppression/failure/rebound, acquired resistance mutations, and ensuing treatment changes. Inputs were taken from trial data (ARTEMIS), literature and, where necessary, stated assumptions. Clinical measures included AIDS events, side effects, time on sequential therapies, cardiovascular events, and expected life-years lost as a result of HIV infection. The model underwent face, technical and partial predictive validation. Treatment-naive individuals similar to those in the ARTEMIS trial were modelled over a lifetime, and outcomes with first-line DRV + RTV were compared with those with LPV/r, both paired with tenofovir and emtricitabine. Up to three regimen changes were permitted. Drug prices were based on wholesale acquisition cost. Outcomes were lifetime healthcare costs (in 2011 US dollars) from the US healthcare system perspective and quality-adjusted life-years (QALYs) (discounted at 3 % per annum).

RESULTS

Choice of LPV/r over DRV + RTV as initial ART resulted in nearly identical clinical outcomes, but distinctly different economic consequences. Starting with an LPV/r regimen potentially results in approximately US$25,000 discounted lifetime savings. Accumulated QALYs for LPV/r and DRV + RTV were 12.130 and 12.083, respectively (a 19-day difference). In sensitivity analyses, net monetary benefit ranged from US$12,000 to US$31,000, favouring LPV/r (base case US$27,762).

CONCLUSIONS

A comprehensive simulation of lifetime course of HIV in the USA indicated that using LPV/r as first-line therapy compared with DRV + RTV may result in cost savings, with similar clinical outcomes.

The cost and impact of scaling up pre-exposure prophylaxis for HIV prevention: a systematic review of cost-effectiveness modelling studies

BACKGROUND

Cost-effectiveness studies inform resource allocation, strategy, and policy development. However, due to their complexity, dependence on assumptions made, and inherent uncertainty, synthesising, and generalising the results can be difficult. We assess cost-effectiveness models evaluating expected health gains and costs of HIV pre-exposure prophylaxis (PrEP) interventions.

METHODS AND FINDINGS

We conducted a systematic review comparing epidemiological and economic assumptions of cost-effectiveness studies using various modelling approaches. The following databases were searched (until January 2013): PubMed/Medline, ISI Web of Knowledge, Centre for Reviews and Dissemination databases, EconLIT, and region-specific databases. We included modelling studies reporting both cost and expected impact of a PrEP roll-out. We explored five issues: prioritisation strategies, adherence, behaviour change, toxicity, and resistance. Of 961 studies retrieved, 13 were included. Studies modelled populations (heterosexual couples, men who have sex with men, people who inject drugs) in generalised and concentrated epidemics from Southern Africa (including South Africa), Ukraine, USA, and Peru. PrEP was found to have the potential to be a cost-effective addition to HIV prevention programmes in specific settings. The extent of the impact of PrEP depended upon assumptions made concerning cost, epidemic context, programme coverage, prioritisation strategies, and individual-level adherence. Delivery of PrEP to key populations at highest risk of HIV exposure appears the most cost-effective strategy. Limitations of this review include the partial geographical coverage, our inability to perform a meta-analysis, and the paucity of information available exploring trade-offs between early treatment and PrEP.

CONCLUSIONS

Our review identifies the main considerations to address in assessing cost-effectiveness analyses of a PrEP intervention--cost, epidemic context, individual adherence level, PrEP programme coverage, and prioritisation strategy. Cost-effectiveness studies indicating where resources can be applied for greatest impact are essential to guide resource allocation decisions; however, the results of such analyses must be considered within the context of the underlying assumptions made. Please see later in the article for the Editors' Summary.

Clinical implications of fixed-dose coformulations of antiretrovirals on the outcome of HIV-1 therapy

The substitution by generic equivalents of some of the drugs included in fixed-dose antiretroviral coformulations (FDACs) poses the potential risk of disrupting these combinations and administering the components separately in order to incorporate the new generic drug, which offers a more competitive sales price. This may represent a step backwards in the advances achieved in simplicity and adherence to therapy, posing an increased risk of selective noncompliance of some of the separately administered drug substances. Available antiretroviral drugs must be administered for life in the affected individuals - both children and adults. The FDACs represent a significant advance in the simplification of antiretroviral therapy, facilitating adherence to complex and chronic treatments, and contributing to a quantifiable improvement in patient quality of life. These drug coformulations reduce the risk of treatment error, are associated with a lower risk of hospitalization, and can lessen the possibility of covert monotherapy in situations of selective noncompliance. Thus, FDACs can reduce the risk of selection of HIV-1 resistances, which not only adversely affect the treatment options of the individual patient but also constitute a public health problem, and further increase the cost and complexity of therapy. With the exception of those cases requiring dose adjustments, the preferential use of FDACs should be recommended for the treatment of HIV-1 infection in those situations when the agents included in the coformulation are drugs of choice.