Cost effectiveness of darunavir/ritonavir 600/100 mg bid in protease inhibitor-experienced, HIV-1-infected adults in Belgium, Italy, Sweden and the UK

Research trends in contemporary health economics: a scientometric analysis on collective content of specialty journals

INTRODUCTION

Health economics is a thriving sub-discipline of economics. Applied health economics research is considered essential in the health care sector and is used extensively by public policy makers. For scholars, it is important to understand the history and status of health economics-when it emerged, the rate of research output, trending topics, and its temporal evolution-to ensure clarity and direction when formulating research questions.

METHODS

Nearly 13,000 articles were analysed, which were found in the collective publications of the ten most specialised health economic journals. We explored this literature using patterns of term co-occurrence and document co-citation.

RESULTS

The research output in this field is growing exponentially. Five main research divisions were identified: (i) macroeconomic evaluation, (ii) microeconomic evaluation, (iii) measurement and valuation of outcomes, (iv) monitoring mechanisms (evaluation), and (v) guidance and appraisal. Document co-citation analysis revealed eighteen major research streams and identified variation in the magnitude of activities in each of the streams. A recent emergence of research activities in health economics was seen in the Medicaid Expansion stream. Established research streams that continue to show high levels of activity include Child Health, Health-related Quality of Life (HRQoL) and Cost-effectiveness. Conversely, Patient Preference, Health Care Expenditure and Economic Evaluation are now past their peak of activity in specialised health economic journals. Analysis also identified several streams that emerged in the past but are no longer active.

CONCLUSIONS

Health economics is a growing field, yet there is minimal evidence of creation of new research trends. Over the past 10 years, the average rate of annual increase in internationally collaborated publications is almost double that of domestic collaborations (8.4% vs 4.9%), but most of the top scholarly collaborations remain between six countries only.

Darunavir: a review of its use in the management of HIV-1 infection

The latest HIV-1 protease inhibitor (PI) darunavir (Prezista™) has a high genetic barrier to resistance development and is active against wild-type HIV and HIV strains no longer susceptible to some older PIs. Ritonavir-boosted darunavir, as a component of antiretroviral therapy (ART), is indicated for the treatment of HIV-1 infection in adult and paediatric patients (aged ≥3 years), with or without treatment experience (details vary depending on region of approval). Several open-label or partially-blinded trials have evaluated the efficacy of ritonavir-boosted darunavir ART regimens for up to 192 weeks in these settings. In treatment-naïve adults, once-daily boosted darunavir was no less effective in establishing virological suppression than once- or twice-daily boosted lopinavir, yet was more effective at maintaining suppression long term. Moreover, treatment-experienced adults with no darunavir resistance-associated mutations (RAMs) had no less effective viral load suppression with once-daily than with twice-daily boosted darunavir. In treatment-experienced adults, including some with multiple major PI RAMs, twice-daily boosted darunavir was more effective than twice-daily boosted lopinavir or boosted control PIs in reducing viral load, and provided virological benefit as part of a salvage regimen in those with few remaining treatment options. Boosted darunavir also reduced viral load when administered once-daily in treatment-naïve adolescents or twice-daily in treatment-experienced children and adolescents. Boosted darunavir is generally well tolerated, with gastrointestinal disturbances and lipid abnormalities among the most common tolerability issues. It has a lipid profile more favourable than that of boosted lopinavir in terms of total cholesterol and triglyceride changes and, when administered once daily, its lipid effects are generally similar to those of boosted atazanavir. Thus, boosted darunavir is a useful option for the ART regimens of adult and paediatric patients with HIV-1 infection.

Cost-minimization comparison of darunavir plus ritonavir and lopinavir/ritonavir in HIV-1 infected treatment-naïve women of childbearing age

BACKGROUND

Guidelines from the Department of Health and Human Services in the US recommend ritonavir-boosted lopinavir (LPV/r) as a preferred protease inhibitor (PI) for HIV-positive antiretroviral-naїve pregnant women. These guidelines also cite ritonavir-boosted darunavir (DRV + RTV) as an alternative PI in this clinical scenario. The purpose of this analysis was to compare economic outcomes for regimens based on these two treatments.

STUDY DESIGN

An existing discrete event simulation (DES) model was adapted to conduct a cost-minimization analysis comparing the two regimens in HIV-infected women of childbearing age (WOCBA), from the perspective of a healthcare payer in the US.

METHODS

The DES model was used to represent disease states, health events, healthcare encounters, pregnancy, and treatment choices in HIV-infected WOCBA starting treatment with regimens based on either LPV/r or DRV + RTV. It also incorporated parameters for individual patient characteristics, and for antiretroviral (ARV) treatment effectiveness, treatment sequencing, clinical progression, and resource use. Potential events included scheduled physician visits; viral suppression; viral rebound; AIDS-related complications; CHD events; treatment discontinuation and switching; ARV treatment side-effects (SE); and death. The primary outcomes were discounted 5-year and 10-year healthcare costs. Alternative scenarios considered different rates of switching from DRV + RTV to LPV/r upon conception.

RESULTS

Compared with DRV + RTV, LPV/r was associated with similar clinical outcomes while offering savings at the 5- and 10-year horizons (of $24,904 and $43,502 per patient, respectively), and in extensive sensitivity analyses. The main driver of the savings was the difference in cost between PIs.

CONCLUSIONS

Starting HIV-infected ARV-treatment-naїve WOCBA on an LPV/r-based regimen is cost-saving and provides similar patient outcomes compared to a DRV + RTV-based regimen.

Cost-effectiveness of newer antiretroviral drugs in treatment-experienced patients with multidrug-resistant HIV disease

OBJECTIVE

Newer antiretroviral drugs provide substantial benefits but are expensive. The cost-effectiveness of using antiretroviral drugs in combination for patients with multidrug-resistant HIV disease was determined.

DESIGN

A cohort state-transition model was built representing treatment-experienced patients with low CD4 counts, high viral load levels, and multidrug-resistant virus. The effectiveness of newer drugs (those approved in 2005 or later) was estimated from published randomized trials. Other parameters were estimated from a randomized trial and from the literature. The model had a lifetime time horizon and used the perspective of an ideal insurer in the United States. The interventions were combination antiretroviral therapy, consisting of 2 newer drugs and 1 conventional drug, compared with 3 conventional drugs. Outcome measures were life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness.

RESULTS

Substituting newer antiretroviral drugs increased expected survival by 3.9 years in advanced HIV disease. The incremental cost-effectiveness ratio of newer, compared with conventional, antiretroviral drugs was $75,556/QALY gained. Sensitivity analyses showed that substituting only one newer antiretroviral drug cost $54,559 to $68,732/QALY, depending on assumptions about efficacy. Substituting 3 newer drugs cost $105,956 to $117,477/QALY. Cost-effectiveness ratios were higher if conventional drugs were not discontinued.

CONCLUSIONS

In treatment-experienced patients with advanced HIV disease, use of newer antiretroviral agents can be cost-effective, given a cost-effectiveness threshold in the range of $50,000 to $75,000 per QALY gained. Newer antiretroviral agents should be used in carefully selected patients for whom less expensive options are clearly inferior.

Cost analysis of initial highly active antiretroviral therapy regimens for managing human immunodeficiency virus-infected patients according to clinical practice in a hospital setting

Objective

In the study reported here, single-tablet regimen (STR) versus (vs) multi-tablet regimen (MTR) strategies were evaluated through a cost analysis in a large cohort of patients starting their first highly active antiretroviral therapy (HAART). Adult human immunodeficiency virus (HIV) 1-naïve patients, followed at the San Raffaele Hospital, Milan, Italy, starting their first-line regimen from June 2008 to April 2012 were included in the analysis.

Methods

The most frequently used first-line HAART regimens (>10%) were grouped into two classes: 1) STR of tenofovir disoproxil fumarate (TDF) + emtricitabine (FTC) + efavirenz (EFV) and 2) MTR including TDF + FTC + EFV, TDF + FTC + atazanavir/ritonavir (ATV/r), TDF + FTC + darunavir/ritonavir (DRV/r), and TDF + FTC + lopinavir/ritoavir (LPV/r). Data were analyzed from the point of view of the Lombardy Regional Health Service. HAART, hospitalizations, visits, medical examinations, and other concomitant non-HAART drug costs were evaluated and price variations included. Descriptive statistics were calculated for baseline demographic, clinical, and laboratory characteristics; associations between categorical variables and type of antiretroviral strategy (STR vs MTR) were examined using chi-square or Fisher’s exact tests. At multivariate analysis, the generalized linear model was used to identify the predictive factors of the overall costs of the first-line HAART regimens.

Results

A total of 474 naïve patients (90% male, mean age 42.2 years, mean baseline HIV-RNA 4.50 log 10 copies/mL, and cluster of differentiation 4 [CD4+] count of 310 cells/μL, with a mean follow-up of 28 months) were included. Patients starting an STR treatment were less frequently antibody-hepatitis C virus positive (4% vs 11%, P=0.040), and had higher mean CD4+ values (351 vs 297 cells/μL, P=0.004) than MTR patients. The mean annual cost per patient in the STR group was €9,213.00 (range: €6,574.71–€33,570.00) and €14,277.00 (range: €5,908.89–€82,310.30) among MTR patients. At multivariate analysis, after adjustment for age, sex, antibody-hepatitis C virus status, HIV risk factors, baseline CD4+, and HIV-RNA, the cost analysis was significantly lower among patients starting an STR treatment than those starting an MTR (adjusted mean: €12,096.00 vs €16,106.00, P=0.0001).

Conclusion

STR was associated with a lower annual cost per patient than MTR, thus can be considered a cost-saving strategy in the treatment of HIV patients. This analysis is an important tool for policy makers and health care professionals to make short- and long-term cost projections and thus assess the impact of these on available budgets.

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.

Virologic and Immunologic Effectiveness at 48 Weeks of Darunavir–Ritonavir-Based Regimens in Treatment-Experienced Persons Living with HIV-1 Infection in Clinical Practice

Introduction:

Published data addressing the effectiveness of darunavir–ritonavir (DRV/r)-based therapy for multiexperienced patients in developing countries are scarce. This study evaluated the 48-week virologic and immunologic effectiveness of salvage therapy based on DRV/r for the treatment of multidrug-experienced HIV-1-infected adults in Brazil.

Materials and Methods:

A multicenter retrospective cohort study was carried out with multidrug-experienced adults who were on a failing antiretroviral therapy and started a DRV/r-based salvage therapy between 2008 and 2010. The primary effectiveness end point was the proportion of patients with virologic success (plasma HIV-1 RNA <50 copies/mL at week 48).

Results:

At 48 weeks, 73% of the patients had HIV-RNA <50 copies/mL and a mean increase of 108 CD4 cells/mm3. Higher baseline viral load, lower baseline CD4 count, younger age, and 3 or more DRV/r-associated resistance mutations were significantly predictive of virologic failure. Concomitant use of raltegravir was strongly associated with virologic success.

Conclusion:

The use of DRV/r-based regimens for salvage therapy is an effective strategy in the clinical care setting of a developing country.

Economic evaluation of initial antiretroviral therapy for HIV-infected patients: an update of Italian guidelines

Introduction

Highly active antiretroviral therapy (HAART) has allowed many HIV-infected patients to enjoy longer survival and a better quality of life. We performed an economic analysis to estimate the cost-effectiveness of HAART regimens in Italy for managing HIV-naïve infected patients with a viral load below 100,000 copies/mL.

Patients and methods

The population considered in the model consisted of adult subjects with an HIV viral load below 100,000 copies/mL who received antiretroviral HAART treatment for the first time, according to the Italian National Guidelines with recommendation grade A1. The incremental cost-effectiveness analysis of quality-adjusted life years (QALYs) was carried out by means of a Markov model. Both the outcomes (QALYs) and the costs were discounted by 3.5%. The time horizon adopted in the model was 10 years. The point of view of the analysis was that of the Italian national health service.

Results

The tenofovir (TDF)/emtricitabine (FTC)/rilpivirine (RPV) single-tablet regimen (STR) (€7,417.00) revealed the lowest mean treatment cost. TDF/FTC + raltegravir (RAL) showed a better quality of life (0.906 QALY/year), followed by TDF/FTC/RPV (STR; 0.900 QALY/year), TDF/FTC + RPV (multipill regimen) (0.889 QALY/year), and TDF/FTC + atazanavir (ATV/r) (0.886 QALY/year). TDF/FTC/RPV (STR) appeared to be the most cost-effective therapeutic choice (€13,655.00), followed by TDF/FTC + RPV (multipill regimen) (€15,803.00), and TDF/FTC + efavirenz (EFV) (€16,181.00). The sensitivity analysis on the main variables confirmed the validity of the base case scenario.

Conclusion

STR (TDF/FTC/RPV) is the most cost-effective treatment strategy compared with the other therapeutic regimens recommended by the Italian guidelines for the treatment of naïve patients with a viral load <100,000 copies/mL. The inclusion of adverse-event management of HIV-infected patients affects the cost-effectiveness ratio of all HAART regimens.

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.

High rate of virologic suppression with darunavir/ritonavir plus optimized background therapy among highly antiretroviral-experienced HIV-infected patients: results of a prospective cohort study in São Paulo, Brazil

Objectives

To assess the virologic and immunological response of darunavir/ritonavir plus optimized background therapy in highly antiretroviral-experienced HIV-infected patients in Brazil.

Methods

Prospective cohort study carried out in a tertiary center in Sao Paulo, Brazil. Three-class antiretroviral-experienced patients with confirmed virologic failure began darunavir/ritonavir plus optimized background therapy (nucleoside/tide reverse transcriptase inhibitors ± raltegravir ± enfuvirtide ± maraviroc) after performing a genotypic resistance assay. Clinical evaluation and laboratory tests were collected at baseline and at weeks 12, 24, and 48. Multivariate analysis was performed to identify predictors of virologic response at 48 weeks.

Results

Ninety-two patients were included. The median of darunavir resistant mutation was 1 (range 0-6). The median genotypic sensitivity score in the optimized background therapy was 2 (interquartile range 1-2). At week 48, 83% (95% CI: 75–90%) had an HIV RNA level <50 copies/mL and the median CD4 cell count was 301 (interquartile range 224-445) cells/mm³. Baseline HIV RNA >100 000 copies/mL was inversely associated with virologic success at week 48 (HR: 0.22, 95% CI: 0.06-0.85, p = 0.028).

Conclusions

Darunavir/ritonavir plus optimized background therapy was a highly effective salvage regimen under clinical routine conditions in a referral center in Brazil, which is similar to the reported in high-income countries.

Economic and health-related quality-of-life (HRQoL) comparison of lopinavir/ritonavir (LPV/r) and atazanavir plus ritonavir (ATV+RTV) based regimens for antiretroviral therapy (ART)-naïve and -experienced United Kingdom patients in 2011

BACKGROUND

Using a United Kingdom (UK)-based National Health Services perspective for 2011 this study first estimated the cost-effectiveness and budget impact implications for lopinavir/ritonavir (LPV/r) vs atazanavir plus ritonavir (ATV+RTV) treatment of antiretroviral therapy (ART)-naïve patients and secondly examined the long-term health-related quality-of-life (HRQoL) and economic implications for LPV/r vs ATV+RTV treatment of ART-experienced patients.

METHODS

A previously published Markov model that integrates epidemiological data of human immunodeficiency virus (HIV) with predictors of coronary heart disease (CHD) was modified under a clearly specified set of assumptions to reflect viral load (VL) suppression profiles and other differences for these two regimens, applying results from the CASTLE study in ART-naïve patients and using data from BMS-045 in ART-experienced patients. ART costs were referenced to current (2011) pricing guidelines in the UK. Medical care costs reflected UK treatment patterns and relevant drug pricing. Costs and outcomes were discounted at 3.5% per year. Costs are expressed in British pounds (£) and life expectancy in quality-adjusted life years (QALYs).

RESULTS

In the ART-naïve subjects, the model predicted a marginal improved life expectancy of 0.031 QALYs (11 days) for the ATV+RTV regimen as a result of predicted CHD outcomes based on lower increases in cholesterol levels compared with the LPV/r regimen. The model demonstrated cost savings with the LPV/r regimen. The total lifetime cost savings was £4070 per patient for the LPV/r regimen. LPV/r saved £2133 and £3409 per patient at 5 and 10 years, respectively. Referenced to LPV/r, the incremental cost-effectiveness ratio (ICER) for ATV+RTV was £149,270/QALY. For ART-experienced patients VL suppression differences favored LPV/r, while CHD risk associated with elevated total cholesterol marginally favored ATV+RTV, resulting in a net improvement in life expectancy of 0.31 QALYs (106 days) for LPV/r. Five-year costs were £5538 per patient greater for ATV+RTV, with a discounted lifetime saving of £1445 per LPV/r patient. LPV/r was modestly dominant economically, producing better outcomes and cost savings.

LIMITATIONS

The limitations of this study include uncertainty related to how well the model's assumptions capture current practice, as well as the validity of the model parameters used. This study was limited to using aggregated data in the public domain from the two clinical trials. Thus, some of the model parameters may reflect limitations due to trial design and data aggregation bias. This study has attempted to illuminate the effect of these limitations by presenting the results of the comprehensive sensitivity analysis.

CONCLUSIONS

Based on 2011 costs of HIV in the UK and the published efficacy data from the CASTLE and BMS-045 studies, ATV+RTV-based regimens are not expected to be a cost-effective use of resources for ART-naïve patients similar to patients in the CASTLE study, nor for ART-experienced patients based on the only published comparison of ATV+RTV and LPV/r.

Cost-effectiveness analysis of initial HIV treatment under Italian guidelines

INTRODUCTION

Since the mid-1990s, highly active antiretroviral therapy (HAART) has modified the clinical course of human immunodeficiency virus (HIV) infection, reducing the rate of disease progression, the incidence of opportunistic infections, and mortality. The authors of this paper performed an economic analysis to estimate the cost-effectiveness of the HAART regimens in Italy for managing HIV-infected patients according to national guidelines.

PATIENTS AND METHODS

The incremental cost-effectiveness analysis was carried out by means of a Markov model, which through a decision-analytic approach, made it possible to compare the studied antiretroviral regimens. The population considered in the model consisted of adult subjects with HIV who received antiretroviral HAART treatment for the first time. The population considered in the analysis reflects the patients' characteristics according to one of the regional surveillance systems HIV/AIDS infection report currently operating in Italy. The analysis was carried out from the point of view of the Italian health care system. The considered outcome measures were quality-adjusted life years (QALYs) and direct health costs calculated for the year 2010. Both the outcomes (QALYs) and the costs were discounted by 3.5%. The time horizon adopted in the model was 10 years.

RESULTS

The model shows, in terms of cost per gained QALY, single tablet regimen (STR) appeared to be the most cost-effective therapeutic choice (€22,017), followed by tenofovir (TDF) + lamivudine + efavirenz (EFV) (€24,526), and TDF/emtricitabine (FTC) + nevirapine (€26,416), and TDF + FTC + EFV (€26,558); the remaining strategies have an incremental cost-effectiveness ratio (ICER) value varying from €28,000 to €41,000 per QALY. The sensitivity analysis on the main variables confirmed the validity of the base case scenario.

CONCLUSION

STR is the most cost-effective treatment strategy, compared with the other therapeutic regimens recommended by the Italian guidelines. All the ICER values of the various regimens considered by the Italian guidelines were lower than the threshold value of €50,000 commonly accepted at the international level. The model developed represents a tool for policy makers and health care professionals to make short- and long-term cost projections and thus evaluate their impact on the available budgets for HIV patients.

A review of economic evaluations of darunavir boosted by low-dose ritonavir in treatment-experienced persons living with HIV infection

Darunavir boosted by low-dose ritonavir (DRV/r), at a daily dose of 600/100 mg twice a day (bid), has been shown to be superior to alternative highly active antiretroviral therapy (HAART) regimens for the management of treatment-experienced, HIV-infected adults in the phase IIb POWER trials and the phase III TITAN trial. Economic analyses of different types that have been performed for several countries to investigate the cost effectiveness and budgetary impact of DRV/r 600/100 mg bid for treatment-experienced people living with HIV (PLHIV) based on the clinical data gathered in the POWER and TITAN trials are reviewed for consistency and their value to different decision-makers is assessed. Cost-utility analyses for the USA and several European countries indicate that DRV/r-based HAART is cost effective compared with other standard of care protease inhibitor (PI)-based regimens in PLHIV with evidence of PI resistance. For all of these countries, the estimated cost-utility ratio is well below typical benchmark values and these ratios are robust, as demonstrated by one-way sensitivity and variability analyses and multi-way probabilistic sensitivity analyses. Studies using other metrics including the average 1-year drug cost per patient with a plasma HIV-RNA level less than 50 copies/mL at 48 weeks, the incremental drug cost per additional patient with a plasma HIV-RNA level less than 50 copies/mL at 48 weeks, the total (antiretroviral and non-antiretroviral) costs during the first year of treatment, and the total healthcare budget impact during the first 5 years of treatment provided further evidence of the positive economic outcomes with the use of DRV/r in treatment-experienced PLHIV. Different measures of economic outcomes are useful for different types of decision-makers and different types of decisions. In general, the results of these different types of analyses will be consistent with each other. For darunavir, the economic analyses reviewed in this paper demonstrate that the use of DRV/r 600/100 mg bid in the management of HIV-infected, treatment-experienced adults who have failed at least one of the other currently available PIs is cost effective and may be cost saving.

The impact of disease stage on direct medical costs of HIV management: a review of the international literature

The global prevalence of HIV infection continues to grow, as a result of increasing incidence in some countries and improved survival where highly active antiretroviral therapy (HAART) is available. Growing healthcare expenditure and shifts in the types of medical resources used have created a greater need for accurate information on the costs of treatment. The objectives of this review were to compare published estimates of direct medical costs for treating HIV and to determine the impact of disease stage on such costs, based on CD4 cell count and plasma viral load. A literature review was conducted to identify studies meeting prespecified criteria for information content, including an original estimate of the direct medical costs of treating an HIV-infected individual, stratified based on markers of disease progression. Three unpublished cost-of-care studies were also included, which were applied in the economic analyses published in this supplement. A two-step procedure was used to convert costs into a common price year (2004) using country-specific health expenditure inflators and, to account for differences in currency, using health-specific purchasing power parities to express all cost estimates in US dollars. In all nine studies meeting the eligibility criteria, infected individuals were followed longitudinally and a 'bottom-up' approach was used to estimate costs. The same patterns were observed in all studies: the lowest CD4 categories had the highest cost; there was a sharp decrease in costs as CD4 cell counts rose towards 100 cells/mm³; and there was a more gradual decline in costs as CD4 cell counts rose above 100 cells/mm³. In the single study reporting cost according to viral load, it was shown that higher plasma viral load level (> 100,000 HIV-RNA copies/mL) was associated with higher costs of care. The results demonstrate that the cost of treating HIV disease increases with disease progression, particularly at CD4 cell counts below 100 cells/mm³. The suggestion that costs increase as the plasma viral load rises needs independent verification. This review of the literature further suggests that publicly available information on the cost of HAART by disease stage is inadequate. To address the information gap, multiple stakeholders (governments, pharmaceutical industry, private insurers and non-governmental organizations) have begun to establish and support an independent, high quality and standardized multicountry data collection for evaluating the cost of HIV management. An accurate, representative and relevant cost-estimate data resource would provide a valuable asset to healthcare planners that may lead to improved policy and decision-making in managing the HIV epidemic.

Modelling the budget impact of darunavir in the treatment of highly treatment-experienced, HIV-infected adults in France

BACKGROUND

A key element for payers in the assessment of the economic profile of a medication is its anticipated impact on the evolution of healthcare budgets.

OBJECTIVES

To forecast the impact of the use of darunavir with low-dose ritonavir 600/100 mg twice a day (bid) in highly treatment-experienced, HIV-infected adults who have failed one or more protease inhibitor (PI)-containing regimen on the budget of the French Sickness Fund (French healthcare system) over a 3-year time horizon.

METHODS

A transition state model based on disease severity was developed that compared the evolution of antiretroviral and non-antiretroviral-related direct costs of care in the target population over 3 years (2007-2009) under two scenarios: (1) darunavir enters the French market in year 1; (2) darunavir is not available to the target population during 2007-2009. Model inputs were derived from a targeted analysis of the French hospital database in HIV, the darunavir POWER 1 and 2 trials and other relevant clinical studies.

RESULTS

In the scenario where darunavir was available from year 1, the proportion of patients in the lower, more costly CD4 cell count strata (≤ 100 cells per mm³) was consistently lower than in the scenario without darunavir in each year of the model (17.0% vs 19.2%, 13.9% vs 18.3% and 10.8% vs 16.8% for years 1, 2 and 3, respectively). As a result, over the entire 3-year period, the net increase of antiretroviral drug costs (+ 5.6 million Euros; €), resulting from the substitution of older, cheaper PIs by darunavir, is expected to be fully compensated by savings in hospitalization costs (€-9.7 million) and expenditures for other HIV-related (non-antiretroviral) medications (€-7.3 million), leading to a net saving of €11.4 million or 2.9% of the total budget in the scenario without darunavir. Various sensitivity analyses confirmed these projected savings.

CONCLUSION

The use of darunavir/ritonavir (DRV/r) 600/100 mg bid, in combination with other antiretroviral agents, in highly pre-treated, HIV-infected adults who have failed one or more PI-containing highly active antiretroviral therapy regimen is not expected to increase the budget of the French healthcare system, in comparison with a scenario without darunavir. Further research is needed to estimate the budget impact of the use of DRV/r in less treatment-experienced, HIV-infected individuals in France.

Cost effectiveness of darunavir/ritonavir in highly treatment-experienced, HIV-1-infected adults in the USA

INTRODUCTION

Darunavir is a new protease inhibitor (PI) that is co-administered with low-dose ritonavir and has demonstrated substantial efficacy in clinical trials of highly treatment-experienced patients when combined with an optimized background regimen (with or without enfuvirtide). This study estimates the cost effectiveness of darunavir with ritonavir (DRV/r) in this population over 5-year and lifetime time horizons in the USA.

METHODS

A Markov model was used to follow a treatment-experienced HIV-1 cohort through six health states, based on CD4 cell count: greater than 500, 351-500, 201-350, 101-200, 51-100 and 0-50 cells/mm³, and death. The magnitude of the CD4 cell count increase and duration of increasing and stable periods were derived from week 48 DRV/r clinical trial results (POWER 1 and 2). The treatment pathway assumed one regimen switch following treatment failure on the initial regimen. The use of antiretroviral drugs was based on usage in DRV/r clinical trials. US daily wholesale acquisition costs were calculated using the recommended daily doses. For each CD4 cell count range, utility values, HIV-1-related mortality rates and costs for medical resources (other than antiretroviral drug costs) were obtained from published literature. Non-HIV-1-related mortality rates were calculated by applying a relative risk value to the US general population age and gender-specific mortality rates. Costs and outcomes were discounted at 3% per year. One-way and probabilistic sensitivity analyses and variability analysis were performed.

RESULTS

In a 5-year analysis, patients receiving DRV/r experienced 3.80 quality-adjusted life-years (QALYs) and incurred total medical costs of US$217,288, while those receiving control PIs experienced 3.60 QALYs and incurred costs of US$218,962. DRV/r was both more effective and less costly than control PIs. For the lifetime analysis, the QALYs and lifetime medical costs with DRV/r were 10.03 and US$565,358, compared with 8.76 and US$527,287 with control PIs. The incremental cost-effectiveness ratio for DRV/r compared with control PIs was US$30,046. One-way sensitivity analyses for both time horizons indicated that the results were most sensitive to changes in the rate of CD4 cell count change during stable and declining periods (lifetime only), duration of stable period (5-year only) and HIV-1-related mortality rates. The results of the variability analysis were most sensitive to the model time horizon. Nevertheless, for all ranges and scenarios tested in these analyses, the incremental cost per QALY gained remained below US$50,000. The probabilistic sensitivity analysis showed that there was a 0.921 and 0.950 probability of a cost-effectiveness ratio below US$50,000 per QALY for the 5-year and lifetime time horizon, respectively.

CONCLUSIONS

DRV/r is predicted to be cost effective compared with control PI in highly treatment-experienced patients and is predicted to yield an average of 0.20 additional QALYs per treatment-experienced patient over 5 years and 1.27 additional QALYs over a lifetime in this population.

US cost effectiveness of darunavir/ritonavir 600/100 mg bid in treatment-experienced, HIV-infected adults with evidence of protease inhibitor resistance included in the TITAN Trial

INTRODUCTION

The phase III TITAN trial evaluated the use of darunavir with low-dose ritonavir (DRV/r) 600/100 mg twice daily (bid) compared with lopinavir with low-dose ritonavir (LPV/r) in treatment-experienced, lopinavir-naive patients. This study estimates the cost effectiveness of DRV/r from a US societal perspective when compared with LPV/r in treatment-experienced patients with a profile similar to those TITAN patients who had one or more International AIDS Society - USA (IAS-USA) primary protease inhibitor (PI) resistance-associated mutations (RAMs) at baseline. This population had less advanced HIV disease and a broader range of previous PI exposure/failure (0 - ≥ 2 PIs) at enrollment than those in the darunavir phase IIb POWER trials.

METHODS

An existing Markov model containing six health states defined by CD4 cell count range (>500, 351-500, 201-350, 101-200, 51-100 and 0-50 cells/mm³) and an absorbing state of death was adapted. Baseline demographics, CD4 cell count distribution and antiretroviral drug usage, virological response (at week 24), and immunological response estimates and matching transition probabilities were based on data collected directly from the one or more IAS-USA PI mutation subpopulation during the first 48 weeks of the TITAN trial, as well as from published literature. Patients were assumed to switch to a regimen containing tipranavir plus an optimized background regimen after treatment failure. For each CD4 cell count range or health state, the utility values, HIV and non-HIV-related mortality rates, and non-antiretroviral-related cost of HIV care estimates were derived from published literature. Unit costs were derived from official local sources. A lifetime horizon was taken in the base-case analysis.

RESULTS

The base-case analysis predicted discounted quality-adjusted survival gains of 0.493 quality-adjusted life-years (QALYs) for DRV/r compared with LPV/r, resulting in an incremental cost-effectiveness ratio (ICER) of US$23,057 per QALY gained over a lifetime horizon. Probabilistic sensitivity analysis indicated a 0.754 probability of an ICER below the threshold of US$50,000 per QALY gained. DRV/r remained cost effective over all parameter ranges tested in extensive one-way sensitivity analyses and variability analyses, which examined the impact of input parameter uncertainty and changes in model assumptions and treatment patterns, respectively. Shortening the model time horizon had the largest impact on the ICER, reducing it most notably to US$4919 with a 10-year time horizon.

CONCLUSION

From a US societal perspective and based on an analysis of the patients with primary IAS-USA PI RAMs enrolled in the darunavir phase III TITAN trial, a highly active antiretroviral therapy (HAART) regimen containing DRV/r 600/100 mg bid is estimated to be a cost-effective therapy when compared with a HAART regimen containing LPV/r, for the management of treatment-experienced, PI-resistant, HIV-infected adults with a broad range of previous PI use/failure.

Cost effectiveness of darunavir/ritonavir 600/100 mg bid in treatment-experienced, lopinavir-naive, protease inhibitor-resistant, HIV-infected adults in Belgium, Italy, Sweden and the UK

BACKGROUND

Using data from the phase IIb POWER trials, darunavir boosted with low-dose ritonavir (DRV/r; 600/100 mg twice daily; bid)-based highly active antiretroviral therapy (HAART) was shown to be significantly more efficacious and cost effective than other protease inhibitor (PI)-based therapy in highly treatment-experienced, HIV-1-infected adults. Furthermore, in the phase III TITAN trial (TMC114-C214), DRV/r 600/100 mg bid-based HAART generated a superior 48-week virological response rate compared with standard-of-care lopinavir/ritonavir (LPV/r; 400/100 mg bid)-based therapy in treatment-experienced, lopinavir-naive patients, and in particular those with one or more International AIDS Society - USA (IAS-USA) primary PI resistance-associated mutations at baseline. These patients had a broader degree of previous PI use/failure (0 - ≥ 2) than the POWER patients.

OBJECTIVES

To determine whether DRV/r 600/100 mg bid-based HAART is cost effective compared with LPV/r-based therapy, from the perspective of Belgian, Italian, Swedish and UK reimbursement authorities, when used in treatment-experienced patients similar to TITAN patients with one or more IAS-USA primary PI mutations at baseline.

METHODS

An existing Markov model containing health states defined by CD4 cell count ranges (>500, 351-500, 201-350, 101-200, 51-100 and 0-50 cells/mm³) and an absorbing state of death was adapted for use in the above-mentioned healthcare settings. Baseline demographics, CD4 cell count distribution, antiretroviral drug usage, virological/immunological response rates and matching transition probabilities were based on data collected during the first 48 weeks of therapy in the modelled subgroup of TITAN patients and the published literature. After treatment failure, patients were assumed to switch to a follow-on combination regimen. For each health state, utility values and mortality rates were obtained from the published literature. Data from local observational studies (Belgium, Sweden and Italy) or the published literature (UK) were used to determine resource-use patterns and costs associated with each CD4 cell count range. Unit costs were derived from official local sources; a lifetime horizon was taken and discount rates were chosen based on local guidelines.

RESULTS

The base-case analysis predicted quality-adjusted life year (QALY) gains of 0.785 in Belgium, 0.608 in Italy, 0.584 in Sweden and 0.550 in the UK when DRV/r-based therapy was used instead of LPV/r-based treatment. The estimated base-case incremental cost-effectiveness ratios (ICERs) were €6964/QALY gained in Belgium, €9277/QALY gained in Italy, €6868 (SEK69,687)/QALY gained in Sweden and €14,778 (£12 612)/QALY gained in the UK. Assuming a threshold of €30,000/QALY gained, DRV/r-based therapy remained cost effective over most parameter ranges tested in extensive one-way sensitivity analyses. The variation of immunological response rates and the time horizon were identified as important drivers of cost effectiveness. Probabilistic sensitivity analysis revealed a greater than 70% probability of achieving an ICER below this threshold in all four healthcare settings.

CONCLUSION

From the perspective of Belgian, Italian, Swedish and UK payers, DRV/r 600/100 mg bid-based HAART is predicted to be cost effective compared with LPV/r 400/100 mg bid-based therapy, when used to manage treatment experienced, lopinavir-naive, PI-resistant, HIV-infected adults with a broad range of previous PI use/failure.