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

Cabotegravir and Rilpivirine Long-Acting Antiretroviral Therapy Administered Every 2 Months is Cost-Effective for the Treatment of HIV-1 in Spain

INTRODUCTION

Current antiretroviral therapies (ARTs) have improved outcomes for people living with HIV. However, the requirement to adhere to lifelong daily oral dosing may be challenging for some people living with HIV, leading to suboptimal adherence and therefore reduced treatment effectiveness. Treatment with long-acting (LA) ART may improve adherence and health-related quality of life. The objective of this study was to evaluate the cost-effectiveness of cabotegravir + rilpivirine (CAB+RPV) LA administered every 2 months (Q2M) compared with current ART administered as daily oral single-tablet regimens (STRs) from a Spanish National Healthcare System perspective.

METHODS

A hybrid decision-tree and Markov state-transition model was used with pooled data from three phase III/IIIb trials (FLAIR, ATLAS, and ATLAS-2M) over a lifetime horizon, with health states defined by viral load and CD4+ cell count. Direct costs (in €) were taken from Spanish public sources from 2021 and several deterministic and probabilistic analyses were carried out. An annual 3% discount rate was applied to both costs and utilities.

RESULTS

Over the lifetime horizon, CAB+RPV LA Q2M was associated with an additional 0.27 quality-adjusted life years (QALYs) and slightly greater lifetime costs (€4003) versus daily oral ART, leading to an incremental cost-effectiveness ratio of €15,003/QALY, below the commonly accepted €30,000/QALY willingness-to-pay threshold in Spain. All scenario analyses showed consistent results, and the probabilistic sensitivity analysis showed cost-effectiveness compared with daily oral STRs in 62.4% of simulations, being dominant in 0.3%.

CONCLUSION

From the Spanish National Health System perspective, CAB+RPV LA Q2M is a cost-effective alternative compared with the current options of daily oral STR regimens for HIV treatment.

CLINICAL TRIALS REGISTRATION

ATLAS, NCT02951052; ATLAS-2M, NCT03299049; FLAIR, NCT02938520.

Machine learning aided multiscale modelling of the HIV-1 infection in the presence of NRTI therapy

Human Immunodeficiency Virus (HIV) is one of the most common chronic infectious diseases in humans. Extending the expected lifetime of patients depends on the use of optimal antiretroviral therapies. Emergence of the drug-resistant strains can reduce the effectiveness of treatments and lead to Acquired Immunodeficiency Syndrome (AIDS), even with antiretroviral therapy. Investigating the genotype-phenotype relationship is a crucial process for optimizing the therapy protocols of the patients. Here, a mathematical modelling framework is proposed to address the impact of existing mutations, timing of initiation, and adherence levels of nucleotide reverse transcriptase inhibitors (NRTIs) on the evolutionary dynamics of the virus strains. For the first time, the existing Stanford HIV drug resistance data have been combined with a multi-strain within-host ordinary differential equation (ODE) model to track the dynamics of the most common NRTI-resistant strains. Overall, the D4T-3TC, D4T-AZT and TDF-D4T drug combinations have been shown to provide higher success rates in preventing treatment failure and further drug resistance. The results are in line with the genotype-phenotype data and pharmacokinetic parameters of the NRTI inhibitors. Moreover, we show that the undetectable mutant strains at the diagnosis have a significant effect on the success/failure rates of the NRTI treatments. Predictions on undetectable strains through our multi-strain within-host model yielded the possible role of viral evolution on the treatment outcomes. It has been recognized that the improvement of multi-scale models can contribute to the understanding of the evolutionary dynamics, and treatment options, and potentially increase the reliability of genotype-phenotype models.

Cost-effectiveness and budget impact of dolutegravir/lamivudine for treatment of human immunodeficiency virus (HIV-1) infection in the United States

BACKGROUND: Dolutegravir(DTG)/lamivudine(3TC) is the first 2-drug regimen recommended as an initial treatment for people living with HIV (PLHIV). OBJECTIVE: To assess the cost-effectiveness and potential budget impact of DTG/3TC in the US healthcare setting. METHODS: A previously published hybrid decision-tree and Markov cohort state transition model was adapted to estimate the incremental costs and health outcome benefits over a patients' lifetime. DTG/3TC was compared with current standard of care in treatment naive and treatment experienced virologically suppressed PLHIV. Health states included in the model were based upon virologic response and CD4 cell count, with death as an absorbing state. Clinical data was informed by the Phase III GEMINI 1 and 2 clinical trials, a published network meta-analysis (NMA) in treatment-naive patients and the Phase III TANGO clinical trial in treatment experienced patients. Costs and utilities were informed by published data and discounted annually at a rate of 3%. A separate 5-year budget impact analysis was conducted assuming 5%-15% uptake in eligible treatment naive and 10%-30% uptake in eligible treatment experienced patients. RESULTS: In the treatment naive analyses based on GEMINI 1 and 2, DTG/3TC dominated, i.e., was less costly and more effective, than all comparators. DTG/3TC resulted in 0.083 incremental quality-adjusted life-years (QALYs) at a cost saving of $199,166 compared with the DTG + tenofovir disoproxil(TDF)/emtricitabine(FTC) comparator arm. The incremental QALY and cost savings for DTG/3TC compared with DTG/abacavir(ABC)/3TC, cobicistat-boosted darunavir(DRV/c)/tenofovir alafenamide(TAF)/FTC, and bictegravir (BIC)/TAF/FTC, based on NMA results were 0.465, 0.142, and 0.698, and $42,948, $122,846, and $44,962, respectively. In the analyses of treatment-experienced virologically suppressed patients based on TANGO, DTG/3TC offered slightly lower QALYs (-0.037) with an estimated savings of $78,730 when compared with continuation of TAF-based regimen (TBR). Sensitivity analyses demonstrated that these conclusions were relatively insensitive to alternative parameter estimates. The budget impact analysis estimated that by 5th year a total of 70,240 treatment naive patients and 1,340,480 treatment experienced patients could be eligible to be prescribed DTG/3TC. The estimated budget savings over 5 years ranged from $1.12b to $3.35b (corresponding to 27,512 to 82,536 on DTG/3TC by year 5) in the lowest and highest uptake scenarios, respectively. CONCLUSION: In conclusion, DTG/3TC with its comparable efficacy and lower drug acquisition costs, has the potential to offer significant cost savings to US healthcare payers for the initial treatment of treatment naive patients and as a treatment switching option for virologically suppressed patients. DISCLOSURES: This study was funded in full by ViiV healthcare, Brentford, UK. Medical writing to support this study was also funded in full by ViiV Healthcare, Brentford, UK. Butler, Hayward, and Jacob are employees of HEOR Ltd, the company performing this study funded by ViiV Healthcare. Anderson is an employee of GlaxoSmithKline and owns shares in the company. Punekar, Evitt, and Oglesby are employees of ViiV Healthcare and own stocks in GlaxoSmithKline.

Cost-Effectiveness of Juluca for Human Immunodeficiency Virus Infection Treatment in Virologically Suppressed Adults in Taiwan

OBJECTIVES

Although the efficacy of traditional 3-drug regimens for the treatment of HIV is well established, tolerability and toxicity concerns remain. New 2-drug regimens such as Juluca (dolutegravir [DTG]/rilpivirine [RPV]) offer noninferior efficacy versus 3-drug regimens (SWORD-1 and SWORD-2 studies), while reducing cumulative drug exposure and potentially long-term toxicities and drug-drug interactions. Here, we assess the cost-effectiveness of DTG/RPV for the treatment of HIV-1 for virologically suppressed adults in Taiwan.

METHODS

A hybrid decision tree and Markov cohort state transition model was used to evaluate the expected economic costs and clinical outcomes associated with DTG/RPV and comparators. Model health states were defined by viral load and CD4 cell count. Efficacy and safety data were informed from SWORD-1 and SWORD-2 studies and the literature. The risk of long-term toxicities (cardiovascular disease, bone fractures, and chronic kidney disease) were included. Current branded drug acquisition prices were included, and healthcare costs informed by a bespoke costing study using National Health Insurance Research Database data. Incremental cost-effectiveness ratios were calculated and compared with a willingness-to-pay threshold of 2 times Taiwan's gross domestic product (NT$1 550 000).

RESULTS

DTG/RPV was found to be a cost-saving regimen compared to 3 comparators (rilpivirine [RPV]/emtricitabine [FTC]/tenofovir disoproxil fumarate [TDF], dolutegravir [DTG]/abacavir [ABC]/lamivudine [3TC], and elvitegravir [EVG]/cobicistat [c]/emtricitabine [FTC]/tenofovir alafenamide [TAF]) and fell in the southwest quadrant of the cost-effectiveness plane where it is generating significant savings with a small decrement in lifetime quality-adjusted life-years (-0.005). It was, however, more expensive than efavirenz [EFV]/emtricitabine [FTC]/ tenofovir disoproxil fumarate [TDF].

CONCLUSIONS

DTG/RPV is cost-saving compared to RPV/FTC/TDF, DTG/ABC/3TC, and EVG/c/FTC/TAF, and provides comparable efficacy with reduced cumulative drug exposure.

Quantitative Evidence Synthesis Methods for the Assessment of the Effectiveness of Treatment Sequences for Clinical and Economic Decision Making: A Review and Taxonomy of Simplifying Assumptions

Sequential use of alternative treatments for chronic conditions represents a complex intervention pathway; previous treatment and patient characteristics affect both the choice and effectiveness of subsequent treatments. This paper critically explores the methods for quantitative evidence synthesis of the effectiveness of sequential treatment options within a health technology assessment (HTA) or similar process. It covers methods for developing summary estimates of clinical effectiveness or the clinical inputs for the cost-effectiveness assessment and can encompass any disease condition. A comprehensive review of current approaches is presented, which considers meta-analytic methods for assessing the clinical effectiveness of treatment sequences and decision-analytic modelling approaches used to evaluate the effectiveness of treatment sequences. Estimating the effectiveness of a sequence of treatments is not straightforward or trivial and is severely hampered by the limitations of the evidence base. Randomised controlled trials (RCTs) of sequences were often absent or very limited. In the absence of sufficient RCTs of whole sequences, there is no single best way to evaluate treatment sequences; however, some approaches could be re-used or adapted, sharing ideas across different disease conditions. Each has advantages and disadvantages, and is influenced by the evidence available, extent of treatment sequences (number of treatment lines or permutations), and complexity of the decision problem. Due to the scarcity of data, modelling studies applied simplifying assumptions to data on discrete treatments. A taxonomy for all possible assumptions was developed, providing a unique resource to aid the critique of existing decision-analytic models.

The Diffusion of Discrete Event Simulation Approaches in Health Care Management in the Past Four Decades: A Comprehensive Review

This study systematically examines the diffusion of the discrete event simulation (DES) approach in health services and health care management by examining relevant factors such as research areas, channels with the objective of promoting the application of DES in the health field. We examined 483 journal papers referencing this approach that were published in 230 journals during 1981 to 2014. The application of DES has extended from health service operational research evaluation to the assessment of interventions in diverse health arenas. The increase in the number of adopters (paper authors) of DES and the increase in number of related channels (journals publishing DES-related articles) are highly correlated, which suggests an increase of DES-related publications in health research. The same conclusion is reached, that is, an increased diffusion of DES in health research, when we focus on the temporal trends of the channels and adopters. The applications of DES in health research cover 22 major areas based on our categorization. The expansion in the health areas also suggests to a certain extent the rapid diffusion of DES in health research.

The Impact of State AIDS Drug Assistance Policies on Clinical and Economic Outcomes of People With HIV

We investigated the effect of changes to state AIDS Drug Assistance Programs (ADAP) policies, which govern access to antiretroviral therapy (ART), on clinical and economic outcomes among low-income people living with HIV/AIDS. Retrospective analyses of ART access were conducted on state ADAP policies, using data from ADAP Monitoring Reports and Kaiser Family Foundation from 2006 to 2010. We found stricter eligibility requirements reduce the number of HIV-positive individuals with ART access through ADAP, and decreased ART use increases mortality by 2.67 quality-adjusted life years (QALYs) per beneficiary. If the ADAP income eligibility cutoff were decreased by 50 percentage points in each state, 4,626 individuals would lose ART access nationwide. Based on a $22,143 cost/QALY, this policy would save $274 million in health care expenditures (2012 dollars), but result in 12,352 QALYs lost, valued at $1.2 billion. Therefore, states should exercise caution in restricting programs that increase ART access for low-income people living with HIV/AIDS.

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.