Cost Effectiveness of Protease Inhibitor Monotherapy Versus Standard Triple Therapy in the Long-Term Management of HIV Patients: Analysis Using Evidence from the PIVOT Trial

Decrementally cost-effective health technologies in non-inferiority studies: A systematic review

Background: HTA guidance has generally been driven by situations where innovative and usually more expensive technologies are compared to the prevailing standards of care. Cheaper and less efficacious interventions have received scarce attention, although strategies with minimal individual efficacy losses might produce collective health gains when savings are redistributed. Purpose: This systematic review of health economic evaluations identified interventions that are both cost and outcome reducing to procure a list of candidate decrementally cost-effective technologies. Data Sources: English language searches were performed in PubMed, EMBASE and ClinicalTrials.gov covering 2005 to September 2021. Study Selection: Full economic evaluations reporting in English decrementally cost-effective health technologies based on RCT data, modelling or mixed methods. Data Synthesis: After filtering 4,975 studies found through the systematic database search, 107 decrementally cost-effective health technologies (HTs) were identified. Nearly a third were services (n = 29) and similarly for drugs (n = 31). For over half of the studies (n = 54) health outcomes were measured in QALYs and the cost-utility ratios varied from €140 to €5 million saved per QALY lost, albeit with time horizons varying from 4 days of follow-up to lifetime extrapolations. Less than a quarter of the studies were carried out from the societal perspective. Limitations: Despite including ClinicalTrials.gov as data source, unpublished studies may have been missed. Conclusions: Our results show a growth in recent years in the number of economic publications demonstrating decrementally cost-effective HTs. Economic tools are needed to facilitate the adoption of such HTs by policy-makers at the national level to maximise health outcomes at the population level. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=95504, identifier CRD42018095504.

HIV Viral Dynamics of Lopinavir/Ritonavir Monotherapy as Second-Line Treatment: A Prospective, Single-Arm Trial

Background:

Characterizing viral response to lopinavir/ritonavir (LPV/r) monotherapy as second-line treatment may guide recommendations for resource-limited settings (RLS).

Methods:

We conducted a 48-week prospective, single-arm study of LPV/r monotherapy in patients failing first-line therapy in Nigeria. The primary outcome was sustained HIV-1 viral load (VL) <400 copies/mL at 48 weeks.

Results:

Of 30 enrolled patients, 28 (93%) achieved viral suppression on LPV/r, while 29 (96%) experienced low-level viremia. At 48 weeks, 9 (30%) met the primary outcome of sustained viral suppression; 14 (47%) patients were suppressed on LPV/r in a snapshot analysis. Detectable VLs at 12 and 24 weeks were strongly associated with treatment failure at 48 weeks. New resistance mutations were not detected. The trial was stopped early due to treatment failure.

Conclusion:

In this study, the rate of virologic failure among patients on a second-line lopinavir monotherapy regimen was relatively high and predicted by early detectable viremia. However, no LPV/r-associated resistance mutations were detected despite fluctuating low-level viremia, demonstrating the high genetic barrier to resistance of the protease inhibitor class which could be useful in RLS.

Cost-Effectiveness Analysis of Lopinavir/Ritonavir Monotherapy Versus Standard Combination Antiretroviral Therapy in HIV-1 Infected Patients with Viral Suppression in France (ANRS 140 DREAM)

BACKGROUND

Protease inhibitor monotherapy is a simplified treatment strategy for virally suppressed HIV-positive patients that has the potential for cost savings, as fewer drugs are used than with combination therapy. However, evidence for its economic value is limited.

OBJECTIVES

We assessed the cost-effectiveness of lopinavir/ritonavir monotherapy followed by treatment intensification in case of viral load rebound versus combination antiretroviral therapy (cART) with efavirenz/emtricitabine/tenofovir in HIV-1 infected patients with viral suppression in the ANRS 140 DREAM trial.

METHODS

DREAM was conducted in 36 French Hospitals between 2009 and 2013. For each treatment strategy, we estimated the unadjusted and multivariate-adjusted mean costs (in €, year 2010 values) and quality-adjusted life-years (QALYs) per patient, as well as incremental costs and QALYs per patient. We then assessed uncertainty using the cost-effectiveness acceptability curve, scenario analyses and cost-effectiveness price-threshold (CEPT) analysis.

RESULTS

In the base-case analysis considering 2009-2013 antiretroviral drug (ARV) prices, adjusted incremental costs and QALYs were - €3296 (95% confidence interval [CI] - 5202 to - 1391) and 0.006 (95% CI - 0.021 to 0.033), respectively, over 2 years, suggesting that monotherapy was cost-effective with a probability of 100% at various cost-effectiveness thresholds. In scenario analyses considering 2018 ARV prices, monotherapy remained cost-effective but with a lower probability (94% vs. 100% in the base-case analysis). The current price of cART would have to decrease by 34% to be cost-effective with a probability of 95%.

CONCLUSION

Monotherapy appears to be cost-effective compared with cART for virologically suppressed HIV-positive patients in France. CEPT analysis is a useful tool to identify the preferred strategy to adopt given that ARV prices change rapidly.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT00946595.

Assessing frontline HIV service provider efficiency using data envelopment analysis: a case study of Philippine social hygiene clinics (SHCs)

BACKGROUND

Globally, local and frontline HIV service delivery units have been deployed to halt the HIV epidemic. However, with the limited resources, there is a need to understand how these units can deliver their optimum outputs/outcomes efficiently given the inputs. This study aims to determine the efficiency of the social hygiene clinics (SHC) in the Philippines as well as to determine the association of the meta-predictor to the efficiencies.

METHODS

In determining efficiency, we used the variables from two data sources namely the 2012 Philippine HIV Costing study and 2011 Integrated HIV Behavioral and Serologic Surveillance, as inputs and outputs, respectively. Various data management protocols and initial assumptions in data matching, imputation and variable selection, were used to create the final dataset with 9 SHCs. We used data envelopment analysis (DEA) to analyse the efficiency, while variations in efficiencies were analysed using Tobit regression with area-specific meta-predictors.

RESULTS

There were potentially inefficient use of limited resources among sampled SHC in both aggregate and key populations. Tobit regression results indicated that income was positively associated with efficiency, while HIV prevalence was negatively associated with the efficiency variations among the SHCs.

CONCLUSIONS

We were able to determine the inefficiently performing SHCs in the Philippines. Though currently inefficient, these SHCs may adjust their inputs and outputs to become efficient in the future. While there were indications of income and HIV prevalence to be associated with the efficiency variations, the results of this case study may only be limited in generalisability, thus further studies are warranted.

Switching to dual/monotherapy determines an increase in CD8+ in HIV-infected individuals: an observational cohort study

BACKGROUND

The CD4/CD8 ratio has been associated with the risk of AIDS and non-AIDS events. We describe trends in immunological parameters in people who underwent a switch to monotherapy or dual therapy, compared to a control group remaining on triple antiretroviral therapy (ART).

METHODS

We included patients in Icona who started a three-drug combination ART regimen from an ART-naïve status and achieved a viral load ≤ 50 copies/mL; they were subsequently switched to another triple or to a mono or double regimen. Standard linear regression at fixed points in time (12-24 months after the switch) and linear mixed model analysis with random intercepts and slopes were used to compare CD4 and CD8 counts and their ratio over time according to regimen types (triple vs. dual and vs. mono).

RESULTS

A total of 1241 patients were included; 1073 switched to triple regimens, 104 to dual (72 with 1 nucleoside reverse transcriptase inhibitor (NRTI), 32 NRTI-sparing), and 64 to monotherapy. At 12 months after the switch, for the multivariable linear regression the mean change in the log₁₀ CD4/CD8 ratio for patients on dual therapy was -0.03 (95% confidence interval (CI) -0.05, -0.0002), and the mean change in CD8 count was +99 (95% CI +12.1, +186.3), taking those on triple therapy as reference. In contrast, there was no evidence for a difference in CD4 count change. When using all counts, there was evidence for a significant difference in the slope of the ratio and CD8 count between people who were switched to triple (points/year change ratio = +0.056, CD8 = -25.7) and those to dual regimen (ratio = -0.029, CD8 = +110.4).

CONCLUSIONS

We found an increase in CD8 lymphocytes in people who were switched to dual regimens compared to those who were switched to triple. Patients on monotherapy did not show significant differences. The long-term implications of this difference should be ascertained.

Darunavir/cobicistat showing similar effectiveness as darunavir/ritonavir monotherapy despite lower trough concentrations

INTRODUCTION

When darunavir (DRV) 800 mg is boosted with 150 mg cobicistat (DRVcobi ), DRV trough concentration (Ctrough ) is about 30% lower as compared to 100 mg ritonavir (DRVrtv ). DRVcobi shows similar virological efficacy as DRVrtv when combined with two nucleos(t)ide analogue reverse-transcriptase inhibitors, but it is unknown whether a lower DRV Ctrough would undermine the effectiveness of DRVcobi when given as monotherapy (mtDRVcobi ).

METHODS

Prospective observational study on virologically suppressed HIV-infected subjects who switched to mtDRVcobi . Virological failure was defined as two consecutive HIV-RNA >200 copies/mL. Efficacy was evaluated by intention-to-treat (ITT) and on-treatment (OT) analyses, and compared with data from a previous cohort of subjects on mtDRVrtv conducted at our centre. Plasma DRV Ctrough was measured using LC-MS/MS.

RESULTS

A total of 234 subjects were enrolled. At week 96, the efficacy rates were 67.8% (CI95 , 61.8 to 73.7) by ITT and 86.9% (CI95 , 78.0 to 87.7) by OT analyses. The corresponding rates in our historical DRVrtv controls were 67.6% (CI95 , 60.0 to 75.2) and 83.6% (CI95 : 77.2 to 90.0). A total of 135 DRV determinations were performed in 83 subjects throughout the follow-up period, with a median plasma DRV Ctrough of 1305 ng/mL (range, 150 to 5895) compared with 1710 ng/mL (range, 200 to 3838) in subjects on monotherapy with DRVrtv (p = 0.05).

CONCLUSIONS

DRV Ctrough was lower in HIV-infected subjects receiving DRVcobi than with DRVrtv . However, this did not appear to influence the efficacy of DRVcobi , when administered as monotherapy.

Replicating Health Economic Models: Firm Foundations or a House of Cards?

Health economic evaluation is a framework for the comparative analysis of the incremental health gains and costs associated with competing decision alternatives. The process of developing health economic models is usually complex, financially expensive and time-consuming. For these reasons, model development is sometimes based on previous model-based analyses; this endeavour is usually referred to as model replication. Such model replication activity may involve the comprehensive reproduction of an existing model or 'borrowing' all or part of a previously developed model structure. Generally speaking, the replication of an existing model may require substantially less effort than developing a new de novo model by bypassing, or undertaking in only a perfunctory manner, certain aspects of model development such as the development of a complete conceptual model and/or comprehensive literature searching for model parameters. A further motivation for model replication may be to draw on the credibility or prestige of previous analyses that have been published and/or used to inform decision making. The acceptability and appropriateness of replicating models depends on the decision-making context: there exists a trade-off between the 'savings' afforded by model replication and the potential 'costs' associated with reduced model credibility due to the omission of certain stages of model development. This paper provides an overview of the different levels of, and motivations for, replicating health economic models, and discusses the advantages, disadvantages and caveats associated with this type of modelling activity. Irrespective of whether replicated models should be considered appropriate or not, complete replicability is generally accepted as a desirable property of health economic models, as reflected in critical appraisal checklists and good practice guidelines. To this end, the feasibility of comprehensive model replication is explored empirically across a small number of recent case studies. Recommendations are put forward for improving reporting standards to enhance comprehensive model replicability.