Economic evaluations of treatments for systemic fungal infections: a systematic review of the literature

Economic evaluation of micafungin versus liposomal amphotericin B (LAmB) for treating patients with candidaemia and invasive candidiasis (IC) in Turkey

Micafungin was reported to be non-inferior to liposomal amphotericin B (LAmB) in treating patients with candidaemia and invasive candidiasis (IC). The current study aimed to evaluate the economic impact of using micafungin versus LAmB for treatment of candidaemia and IC in Turkey. A decision analytic model, which depicted economic consequences upon administration of micafungin or LAmB for treating patients with candidaemia and IC in the Turkish hospitals, was constructed. Patients were switched to an alternative antifungal agent if initial treatment failed due to mycological persistence. All patients were followed up until treatment success or death. Outcome probabilities were obtained from published literature and cost inputs were derived from the latest Turkish resources. Expert panels were used to estimate data that were not available in the literature. Cost per patient treated for each intervention was then calculated. Sensitivity analyses including Monte Carlo simulation were performed. For treatment of candidaemia and IC, micafungin (€4809) was associated with higher total cost than LAmB (€4467), with an additional cost of €341 per treated patient. Cost of initial antifungal treatment was the major cost driver for both comparators. The model outcome was robust over a wide variation in input variables except for drug acquisition cost and duration of initial antifungal treatment with micafungin or LAmB. LAmB is cost-saving relative to micafungin for the treatment of candidaemia and IC from the Turkish hospital perspective, with variation in drug acquisition cost of the critical factor affecting the model outcome.

Pharmacoeconomic evaluation of micafungin versus caspofungin as definitive therapy for candidaemia and invasive candidiasis (IC) in Turkey

Micafungin was shown to be as efficacious as caspofungin in treating patients with candidaemia and invasive candidiasis (IC). However, it remains unknown if micafungin or caspofungin is a cost-effective definitive therapy for candidaemia and IC in Turkey. The present study aimed to determine the economic impact of using micafungin versus caspofungin for treatment of candidaemia and IC in the Turkish setting. A decision analytic model was constructed and was populated with data (i.e. transition probabilities, duration of initial antifungal treatment, reasons for treatment failure, percentage of patients who stepped down to oral fluconazole, and duration on oral fluconazole) obtained from a published randomised clinical trial. Cost inputs were derived from the latest Turkish resources while data that were not readily available in the literature were estimated by expert panels. One-way sensitivity analyses, threshold analyses, scenario analyses and probabilistic sensitivity analyses were conducted. Caspofungin (€2693) incurred a lower total cost than micafungin (€4422), with a net cost saving of €1729 per treated patient. Drug acquisition cost was the main cost driver for both study arms. The model outcome was robust over wide variations (of ±100.0% from the base case value) for all input parameters except for micafungin drug cost and the duration of initial treatment with micafungin. Caspofungin appears to be a cost-saving option in treating candidaemia and IC from the Turkish hospital perspective.

Cost-effectiveness analysis of anidulafungin vs fluconazole for the treatment of invasive candidiasis (IC) in Turkey

Anidulafungin has been shown to be non-inferior to, and possibly more efficacious, than fluconazole in treating patients with invasive candidiasis (IC). This study aimed to determine the cost-effectiveness of anidulafungin vs fluconazole for treatment of IC in the Turkish setting. A decision analytic model was constructed to depict downstream economic consequences of using anidulafungin or fluconazole for treatment of IC in the Turkish hospitals. Transition probabilities (ie treatment success, observed or indeterminate treatment failures) were obtained from a published randomised clinical trial. Cost inputs were from the latest Turkish resources. Data not available in the literature were estimated by expert panels. Sensitivity analyses were performed to assess the robustness of the model outcome. While anidulafungin [TL 17 171 (USD 4589)] incurred a higher total cost than fluconazole [TL 8233 (USD 2200) per treated patient, treatment with anidulafungin was estimated to save an additional 0.58 life-years, with an incremental cost-effectiveness ratio of TL 15 410 (USD 4118) per life-years saved. Drug acquisition cost and hospitalisation were the main cost drivers for anidulafungin and fluconazole arms respectively. The model findings were robust over a wide range of input variables except for anidulafungin drug cost. Anidulafungin appears to be a cost-effective therapy in treating IC from the Turkish hospital perspective.

Association between drug tolerability and medical resource use in prophylaxis of invasive fungal infections after allogeneic hematopoietic stem cell transplant

OBJECTIVES

To conduct a retrospective analysis of the association between drug tolerability and potential economic impact measured by medical resource utilization (MRU) for prophylaxis of invasive antifungal infections (IFI) after allogeneic hematopoietic stem cell transplantation (alloHCT).

METHODS

An open-label, multi-center study (IMPROVIT) included patients (≥12-years old) who were randomized to receive oral voriconazole (VOR) or oral itraconazole (ITR) from the alloHCT day for at least 100 days and up to 180 days. Trial data on discontinuation and MRU for the first 100 days were analyzed.

RESULTS

Two hundred and twenty-four patients were in VOR and 241 in ITR, with similar demographic distributions (average age of 43 years, 58% male, 92% Caucasian). All-cause and study drug intolerance discontinuations were less frequent with VOR than ITR (50% vs 63%, p = 0.0137; 7% vs 22%, p < 0.0001). VOR patients had longer study drug exposure (median = 96 vs 68 days, p < 0.0001; mean = 68 vs 60 days, p = 0.0044). ITR patients were 2-times more likely (p = 0.0110) to use other antifungals vs VOR patients. Controlling for treatment and key baseline variables, longer IFI prophylaxis was associated with fewer hospital days (p < 0.0001) and less other antifungal use (p < 0.0001). Patients who discontinued prophylaxis during the first 100 days incurred 10 more hospital days (p < 0.0001) and 17 more other antifungal days (p < 0.0001) compared to their counterparts. Eight more prophylaxis days were associated with ∼1 less hospital day and 3.6 less other antifungal days (p < 0.0001). Key limitation: MRU data collection was limited to the first 100 days post-transplant, which may not fully capture the real-world utilization and outcomes.

CONCLUSIONS

Patients' ability to tolerate and continue their antifungal prophylaxis after alloHCT is associated with less use of MRU such as other antifungals and hospital days. In the current resource-constrained healthcare environment, it is important to consider the potential economic impact of the tolerability of antifungal prophylaxis.

Cost benefit and cost effectiveness of antifungal prophylaxis in immunocompromised patients treated for haematological malignancies: reviewing the available evidence

There has been a large increase in the incidence of invasive fungal infections (IFIs) over the past decades, largely because of the increasing size of the population at risk. One of the major risk groups for IFIs are patients with haematological malignancies treated with cytotoxic chemotherapy or undergoing haematopoietic stem cell transplantation. These IFIs are associated with high morbidity and mortality rates. Consequently, as the diagnosis of IFIs is difficult, antifungal prophylaxis is desirable in high-risk patients. Furthermore, as the economic impact of IFIs is also significant, it is important to assess the cost benefit and cost effectiveness of each prophylactic agent in order to aid decisions concerning which prophylactic agent provides the best value for limited healthcare resources. This article systematically reviews the available pharmacoeconomic evidence regarding antifungal prophylaxis in immunocompromised patients treated for haematological malignancies. Furthermore, specific points of interest concerning economic analyses of antifungal prophylaxis are briefly discussed. Considering the available evidence, antifungal prophylaxis in immunocompromised patients treated for haematological malignancies seems to be an intervention with favourable cost-benefit, cost-effectiveness and cost-saving potential. Furthermore, recently introduced antifungal agents seem to be attractive alternatives to fluconazole from a pharmacoeconomic point of view. However, due to wide heterogeneity in patient characteristics, underlying diseases, hospital settings and study methods in the included economic studies, as well as the lack of 'head-to-head' trials, it is difficult to find clear evidence of the economic advantages of a single prophylactic agent. Furthermore, we show that the results of cost-effectiveness analyses are highly dependent on several crucial factors that influence the baseline IFI incidence rates and, therefore, differ per patient population or region.

Pharmacoeconomic analysis of voriconazole vs. caspofungin in the empirical antifungal therapy of febrile neutropenia in Australia

In two major clinical trials, voriconazole and caspofungin were recommended as alternatives to liposomal amphotericin B for empirical use in febrile neutropenia. This study investigated the health economic impact of using voriconazole vs. caspofungin in patients with febrile neutropenia. A decision analytic model was developed to measure downstream consequences of empirical antifungal therapy. Clinical outcomes measured were success, breakthrough infection, persistent base-line infection, persistent fever, premature discontinuation and death. Treatment transition probabilities and patterns were directly derived from data in two relevant randomised controlled trials. Resource use was estimated using an expert clinical panel. Cost inputs were obtained from latest Australian sources. The analysis adopted the perspective of the Australian hospital system. The use of caspofungin led to a lower expected mean cost per patient than voriconazole (AU$40,558 vs. AU$41,356), with a net cost saving of AU$798 (1.9%) per patient. Results were most sensitive to the duration of therapy and the alternative therapy used post-discontinuation. In uncertainty analysis, the cost associated with caspofungin is less than that with voriconazole in 65.5% of cases. This is the first economic evaluation of voriconazole vs. caspofungin for empirical therapy. Caspofungin appears to have a higher probability of having cost-savings than voriconazole for empirical therapy. The difference between the two medications does not seem to be statistically significant however.

Cost-effectiveness analysis of anidulafungin versus fluconazole for the treatment of invasive candidiasis

BACKGROUND

Anidulafungin was found to be non-inferior to and possibly more efficacious than fluconazole for treatment of invasive candidiasis (IC) in a major randomized clinical trial (RCT). There are no data comparing the cost-effectiveness between azoles and echinocandins in treating IC. This economic analysis investigated the cost-effectiveness of anidulafungin compared with fluconazole for treatment of IC in an Australian setting.

METHODS

A decision analytic model was constructed to capture downstream consequences of using either agent for treatment of IC. The main outcomes analysed in the model were treatment success and treatment failure (observed and indeterminate). Outcome probabilities and treatment pathways were derived from a published RCT. Resources used were estimated by an expert panel and cost inputs were derived from the latest Australian resources. The analysis was based on an Australian hospital perspective. Sensitivity analyses were conducted using Monte Carlo simulation.

RESULTS

Anidulafungin (AU$74,587) had a higher total cost than fluconazole (AU$60,945) per successfully treated patient, primarily due to its higher acquisition cost. Hospitalization was the main cost driver for both comparators. However, when the rates of mortality in both treatment arms were considered, treatment with anidulafungin was expected to save an additional 0.53 life-years, with an incremental cost-effectiveness ratio (ICER) of AU$25 740 per life-years saved, which was below the implicit ICER threshold value for Australia. The results were robust over a wide range of variables.

CONCLUSIONS

This is the first economic evaluation of anidulafungin versus fluconazole in the treatment of IC in Australia. Anidulafungin appears to be a cost-effective option.

Pharmacoeconomics of voriconazole

IMPORTANCE OF THE FIELD

The recent increase in the use of antineoplastic and immune suppressive agents and the use of broad-spectrum antibiotics, prosthetic interventions, organ transplants and more aggressive surgery have been related to a greater prevalence of invasive fungal infections (IFI). Over the past few years, several new antifungal therapies have become available for these patients. Pharmacoeconomic data can play a useful role in comparing the relative benefits of treatment.

AREAS COVERED IN THIS REVIEW

This review summarizes all the available evidence regarding the pharmacoeconomics of voriconazole. A systematic review of pharmacoeconomic analyses through a non-restricted literature search was conducted (until May 2009).

WHAT THE READER WILL GAIN

The reader will gain a greater understanding of the pharmacoeconomics role of voriconazole.

TAKE HOME MESSAGE

The majority of economic analyses have shown that voriconazole is a more cost-effective alternative in the treatment of invasive fungal infections than the antifungal drugs with which it was compared.

Overview of the changing epidemiology of candidemia

Candida spp. are currently the fourth most common cause of bloodstream infections in US hospitals, and the third most common cause of bloodstream infections in the intensive care unit. Over the last 2 decades there has been a shift towards a greater involvement of non-Candida albicans spp. as the cause of candidemia. Several of these non-albicans spp. (e.g., C. glabrata and C. krusei ) exhibit resistance to traditional triazole antifungals like fluconazole, and cross-resistance with newer triazoles, focusing attention on the first-line use of antifungals such as the echinocandins, which possess improved activity against fluconazole-resistant strains. Recent treatment guidelines from the Infectious Diseases Society of America (IDSA) recommend an echinocandin as primary therapy for nonneutropenic or neutropenic patients with moderately severe to severe candidiasis and for patients at risk for infection with a triazole-resistant strain. However, further improvement in candidemia-associated mortality will only be attainable with the development and validation of new diagnostic tools that will allow earlier detection, discrimination, and treatment of invasive candidiasis. Clinicians should remain vigilant to wider emergence of Candida spp. with echinocandin resistance.

Dose tolerability of chronically inhaled voriconazole solution in rodents

Invasive pulmonary aspergillosis (IPA) is a fungal disease of the lung associated with high mortality rates in immunosuppressed patients despite treatment. Targeted drug delivery of aqueous voriconazole solutions has been shown in previous studies to produce high tissue and plasma drug concentrations as well as improved survival in a murine model of IPA. In the present study, rats were exposed to 20 min nebulizations of normal saline (control group) or aerosolized aqueous solutions of voriconazole at 15.625 mg (low dose group) or 31.25mg (high dose group). Peak voriconazole concentrations in rat lung tissue and plasma after 3 days of twice daily dosing in the high dose group were 0.85+/-0.63 microg/g wet lung weight and 0.58+/-0.30 microg/mL, with low dose group lung and plasma concentrations of 0.38+/-0.01 microg/g wet lung weight and 0.09+/-0.06 microg/mL, respectively. Trough plasma concentrations were low but demonstrated some drug accumulation over 21 days of inhaled voriconazole administered twice daily. Following multiple inhaled doses, statistically significant but clinically irrelevant abnormalities in laboratory values were observed. Histopathology also revealed an increase in the number of alveolar macrophages but without inflammation or ulceration of the airway, interstitial changes, or edema. Inhaled voriconazole was well tolerated in a rat model of drug inhalation.

Economic impact of caspofungin as compared with liposomal amphotericin B for empirical therapy in febrile neutropenia in Australia

BACKGROUND

In a major clinical trial, caspofungin was as efficacious as liposomal amphotericin B (LAmB) for empirical therapy in febrile neutropenia. The current study sought to evaluate the economic impact of caspofungin as compared with LAmB for febrile neutropenia in Australia.

METHODS

A decision analytic model was developed to capture the downstream consequences of the empirical antifungal therapy. The main outcomes were success, breakthrough infection, persistent baseline infection, persistent fever, premature discontinuation and death. Underlying transition probabilities and treatment patterns were derived directly from trial data. Resource use was estimated using an expert panel. Cost inputs were obtained from the latest Australian representative sources. The perspective adopted was that of the Australian hospital system. Uncertainty and sensitivity analyses were undertaken via Monte Carlo simulation.

RESULTS

Caspofungin was associated with a net cost saving of AU$7245 (12.6%) per patient over LAmB (AU$50 267 versus AU$57 512). A similar trend was observed with cost per success and death prevented (AU$24 169 and AU$7270, respectively). Caspofungin dominated LAmB as it resulted in higher efficacy and lower costs when compared with LAmB. Persistent fever was the main contributing clinical outcome to the therapeutic costs of both antifungals. The results were most sensitive to therapy duration. Monte Carlo simulation suggested a 99.8% chance for LAmB to cost more than caspofungin.

CONCLUSIONS

This is the first economic study to evaluate the place of caspofungin as empirical therapy in Australia. Caspofungin is more cost-beneficial than LAmB, which contradicts the current Australian guidelines of recommending LAmB as the first choice for empirical therapy.

Management of Candida infections in the adult intensive care unit

The epidemiology of Candida infection in intensive care units (ICUs) and the management strategies for such infections in non-neutropenic intensive care patients are discussed in this review. Candida species are one of the leading causes of nosocomial bloodstream infections and a significant cause of morbidity in patients admitted to the ICU. Prophylactic, pre-emptive and empiric treatment strategies for Candida infections have been explored in ICU patients. Routine prophylaxis should not be administered to the whole population of ICU patients, because the concerns about the selection of azole-resistant Candida strains or the induction of resistance are justified. Treatment of fungal infections is now possible with newer antifungal agents, including newer azoles (e.g., voriconazole, posaconazole) and echinocandins (e.g., micafungin, anidulafungin). However, there is a critical need for improvement in diagnosis of invasive Candida infection in order to provide clinicians the opportunity to intervene earlier in the diseases course.

Economic evaluation of targeted treatments of invasive aspergillosis in adult haematopoietic stem cell transplant recipients in the Netherlands: a modelling approach

OBJECTIVES

The aim of this study was to assess the cost-effectiveness of a targeted treatment model of antifungal treatment strategies for adult haematopoietic stem cell transplant (HSCT) recipients in the Netherlands from a hospital perspective, using a decision analytic modelling approach.

METHODS

The economic evaluation of desoxycholate amphotericin B, liposomal amphotericin B, voriconazole and caspofungin was undertaken. These drugs could be used alone, in various combinations or sequentially. In our model, first-line therapy consisted of either voriconazole or liposomal amphotericin B. If necessary, treatment was switched to a second-line treatment, including combination antifungal therapy. The theoretical population in this model consisted of adult HSCT recipients with proven or probable invasive aspergillosis (IA). Long-term survival was extrapolated from survival after 12 weeks of treatment and life expectancy.

RESULTS

First-line antifungal treatment strategies with voriconazole were both more effective and less costly over first-line strategies employing liposomal amphotericin B at a dosage of 4 mg/kg/day. The strategy of voriconazole followed by caspofungin (voriconazole/caspofungin) was dominant over the strategies of voriconazole followed by liposomal amphotericin B (voriconazole/liposomal amphotericin B) or desoxycholate amphotericin B (voriconazole/desoxycholate amphotericin B). However, the voriconazole followed by the combination of liposomal amphotericin B and caspofungin strategy (voriconazole/liposomal amphotericin B+caspofungin) was more effective though more expensive than the voriconazole/caspofungin strategy resulting in an incremental cost-effectiveness ratio (ICER) of about euro107,000 for a life-year saved. At a dosage of 1 mg/kg/day of liposomal amphotericin B, the voriconazole/caspofungin strategy was more effective but more costly than the voriconazole/desoxycholate amphotericin B strategy with an ICER of euro10,000 for each extra life-year saved. Between the voriconazole/liposomal amphotericin B+caspofungin and the voriconazole/caspofungin strategies, the ICER was euro40,000.

CONCLUSIONS

Probabilistic analyses on net monetary benefit showed that the voriconazole/caspofungin strategy had the highest probability of being the most cost-effective strategy.

Economic evaluation of the prevention and management of systemic fungal infections in neutropenic patients

Systemic fungal infections in neutropenic patients remain a clinical problem that is associated with morbidity and mortality. Continuing efforts are being made to develop improved (i.e., more effective or safe) drugs, and several new treatments have recently become available. These have increased the therapeutic options available to clinicians to address the problem of systemic fungal infections. Therapeutic choices are difficult when taking into account aspects of efficacy, safety and costs that are associated with the available alternatives. This review summarises the present status of health economic knowledge of the standard therapies that have been available for many years, and also reports on the most recent health economic evidence available for the newly developed treatment alternatives.

Pharmacoeconomics of antifungal pharmacotherapy – challenges and future directions

The frequency and severity of invasive fungal infections have been increasingly recognised and new antifungal therapies have expanded the therapeutic armamentarium available to manage such infections. Antifungal agents comprise a significant portion of antibiotic expenditures at major medical centres, prompting adoption of cost-containment measures and treatment guidelines. This paper reviews available data regarding the costs associated with managing fungal infections, including pharmacoeconomic analyses that have been performed in the setting of documented fungal infections, as well as prophylactic and empiric use of antifungal agents. The challenges of performing such studies are discussed, as well as the limitations of published investigations. Finally, recommendations are made regarding the design and implementation of future pharmacoeconomic analyses that can help establish the true costs of managing invasive fungal infections in at-risk patient populations.

Economic Evaluation of Intravenous Itraconazole for Presumed Systemic Fungal Infections in Neutropenic Patients in Korea

Systemic fungal infections remain a major clinical problem in immunocompromised patients. Presumed systemic fungal infections (PSFI) are treated empirically with an intravenous antifungal agent to reduce the occurrence of documented infections and associated mortality. The objective of this study was to compare the cost-effectiveness of intravenous itraconazole (IVitra) treatment with the current first-line empirical treatment of PSFI with conventional amphotericin B (CAB) in cases of neutropenic cancer and bone marrow transplantation (BMT). Cost-effectiveness was expressed as cost per additional "responder" (defined as a patient without fever or major toxicity). We developed a medical decision analytical tree that included probabilities of toxicity, response and pathogen documentation, and second-line treatments. Clinical data were obtained from randomized clinical trials, and resource use data were obtained from a panel of clinical experts. The total cost of treating PSFI per neutropenic cancer patient was lower for IVitra than for CAB, and this lower cost resulted from a reduced need for second-line antifungals. In a cost-effectiveness analysis, IVitra treatment was superior to CAB treatment. Compared with current treatment with CAB, IVitra therapy was shown to be a cost-effective and cost-saving empirical treatment for PSFI in neutropenic cancer patients and BMT patients.