A comprehensive assessment of the prolonged febrile neutropenia evaluation in pediatric oncology patients.

BACKGROUND: Pediatric oncology patients with prolonged (≥96 hours) febrile neutropenia (absolute neutrophil count < 500/µL) often undergo an evaluation for invasive fungal disease (IFD) and other infections. Current literature suggests that beta-D-glucan (BDG), galactomannan, bronchoalveolar lavage (BAL), and computed tomography (CT) scans (sinus, chest, and abdomen/pelvis) may help determine a diagnosis in this population. METHODS: In a retrospective cohort study of all cancer/stem cell transplant patients (diagnosed 2005-2019) from one pediatric hospital, all episodes with prolonged febrile neutropenia or IFD evaluations (defined as sending a fungal biomarker or performing a CT scan to assess for infection) were identified. RESULTS: In total, 503 episodes met inclusion criteria and 64% underwent IFD evaluations. In total, 36.4% of episodes documented an infection after initiation of prolonged febrile evaluation, most commonly Clostridioides difficile colitis (6.4%) followed by a true bacterial bloodstream infection (BSI) (5.2%), proven/probable IFD (4.8%), and positive respiratory pathogen panel (3.6%). There was no difference in sinus CTs showing sinusitis (74% vs 63%, p = 0.46), whereas 32% of abdomen/pelvis CTs led to a non-IFD diagnosis, and 25% of chest CTs showed possible pneumonia. On chest CT, the positive predictive value (PPV) for IFD was 19% for nodules and 14% for tree and bud lesions. BDG had a PPV of 25% for IFD and GM 50%. BAL diagnosed IFD once and pneumocystis jirovecii pneumonia twice. CONCLUSIONS: Chest CTs and abdomen/pelvis CTs provide clinically relevant information during the prolonged febrile neutropenia evaluation, whereas BDG, galactomannan, BAL, and sinus CTs have less certain utility.

The Austrian landscape of diagnostic capacity and access to treatment for invasive fungal infections.

INTRODUCTION: Immunosuppression after chemotherapy, stem cell transplantation or solid organ transplantation are the main risk factors for invasive fungal infections in Austria. Here, we aim to describe the status of laboratory mycology and the access to antifungal treatment in Austria. METHODS: Between October and November 2021, hospitals were contacted to participate in our online survey: www.clinicalsurveys.net/uc/IFI_management_capacity/. Centres were required to provide information on their institutional profile; self-assessment of burden of invasive fungal infections; access to microscopy, culture, serology, antigen detection and molecular testing; and availability of antifungal agents and therapeutic drug monitoring. RESULTS: Responses were collected from university hospitals and laboratories in Graz, Innsbruck, Linz and Vienna. The four hospitals can provide tertiary care and were highly specialised, including management of patients with severe immunosuppression. All sites consider the incidence of invasive fungal infections to be moderate. Access to microscopy, culture, serology, antigen detection and molecular testing is provided regardless of laboratory. The maximum capacity to identify fungi varies from institution to institution. All currently marketed antifungal agents are available at the four sites. CONCLUSION: Austria is currently well equipped to deal with the emerging threat of invasive fungal infections. However, hospitals may consider preparing for the potential endemicity of certain infections in the near future.

A systematic review of epidemiology, risk factors, diagnosis, antifungal resistance, and management of invasive aspergillosis in Africa.

Invasive aspergillosis (IA) affects more than 300,000 people annually worldwide with a case fatality rate reaching 80%. However, in Africa despite the presence of risk factors for the development of IA, the burden of these fungal infections remained unknown. This systematic review aimed to update the available information on the epidemiology and the therapeutic management of IA in Africa. The published papers were systematically searched on major medical databases from September 20 to October 10, 2021. The list of references of eligible articles and the Google scholar database were also checked in order to search for possible eligible articles. Results were reported following the Preferred Reporting Items for Systematic and Meta-analyses (PRISMA) guidelines. The search yielded 1864 articles of which 29 met the inclusion criteria. This systematic review showed the existence of IA in Africa. The prevalence of IA can reach 27% with a fatality rate of more than 60%. The most common clinical form of IA found was invasive pulmonary aspergillosis. The main predisposing conditions identified were neutropenia, HIV/AIDS, renal transplant recipients, and renal failure. Aspergillus section Flavi and Nigri were the main Aspergillus species identified and Aspergillus section Fumigati was uncommon. The main management strategy for IA cases was to start antifungal therapy only after a failure of broad-spectrum antibiotic therapy. This review provided evidence of the existence of invasive aspergillosis in Africa and especially a high rate of undiagnosed invasive aspergillosis cases.

Real-World Financial and Clinical Impact of Diagnostic-Driven and Empirical-Treatment Strategies in High-Risk Immunocompromised Patients with Suspected Aspergillus Infection in the United Kingdom.

A diagnostic-driven (DD) treatment strategy has proven successful for treating invasive fungal infections (IFIs) caused by Aspergillus. However, uptake of this treatment strategy is not fully embraced. This study compares the economic and clinical impact of DD and empirical-treatment (ET) strategies used within hospitals. Methods: a decision-analytic model was developed to compare costs and clinical outcomes associated with ET or a DD strategy of identifying infections caused by Aspergillus via galactomannan-antigen testing or Aspergillus polymerase chain reaction (PCR) in neutropenic patients with unexplained fever. Patients were treated prophylactically with antifungal treatments as seen in United Kingdom (UK) hospitals. The IFI incidence, response, mortality, resource use, and adverse events were obtained from meta-analyses and other clinical studies. Analyses were performed from the U.K. hospital perspective, and costs were obtained from standard costing sources. Although diagnostic-testing costs increased, total cost and length of stay were reduced by £1,121 and 1.54 days when treating via a DD strategy. Intensive care and general ward days accounted for > 40% of total costs and > 58% of the cost reduction came from reduced antifungal costs. Treating with a DD strategy reduced the number of patients being treated with antifungal agents while survival was increased. Thus, a DD strategy was cost savings (-£136,787 cost per death avoided) compared with an ET strategy. Conclusion: this study suggests that incorporating a DD strategy as the preferred treatment protocol may be a cost-saving and clinically improved treatment strategy for managing neutropenic patients with unexplained fever. IMPORTANCE Patients at risk of invasive fungal infections (IFIs), such as Aspergillus spp., tend to be immunocompromised and usually take several medications which may generate many side effects. Prescribing is further complicated by comorbidities, drug interactions and challenges accessing diagnostics. Therefore, adding another agent may be neither straightforward nor the best option for these types of patients. A diagnostic-driven (DD) treatment strategy has proven successful for treating IFIs. However, uptake of this treatment strategy is not fully embraced in clinical practice perhaps because this strategy is thought to be more costly and/or to result in higher mortality relative to treating empirically. We developed a decision-analytic model to examine the impact of these 2 strategies on costs and health outcomes. This study indicates that incorporating a DD strategy as the preferred treatment protocol may be a cost-saving and clinically improved treatment strategy for managing neutropenic patients with unexplained fever.

Can Beta-D-Glucan testing as part of the diagnostic pathway for invasive fungal infection reduce anti-fungal treatment costs?

We performed a cost comparison of the current diagnostic and treatment pathway for invasive fungal infection (IFI) versus a proposed pathway that incorporates Beta-D-Glucan (BDG) testing from the NHS perspective. A fungal pathogen was identified in 58/107 (54.2%) patients treated with systemic anti-fungals in the Critical Care Department. Mean therapy duration was 23 days (standard deviation [SD] = 22 days), and cost was £5590 (SD = £7410) per patient. Implementation of BDG tests in the diagnostic and treatment pathway of patients with suspected IFI could result in a mean saving of £1643 per patient should a result be returned within 2 days. LAY SUMMARY: Invasive fungal infection increases the risk of death in very sick people. So, treatment is started before test results are known. Beta-D-Glucan (BDG) test is faster than standard blood culture tests. We estimate that using BDG tests in how patients are diagnosed could save about £1643 per patient.

Invasive aspergillosis in solid organ transplant patients: diagnosis, prophylaxis, treatment, and assessment of response.

BACKGROUND: Invasive aspergillosis (IA) is a rare complication in solid organ transplant (SOT) recipients. Although IA has significant implications on graft and patient survival, data on diagnosis and management of this infection in SOT recipients are still limited. METHODS: Discussion of current practices and limitations in the diagnosis, prophylaxis, and treatment of IA and proposal of means of assessing treatment response in SOT recipients. RESULTS: Liver, lung, heart or kidney transplant recipients have common as well as different risk factors to the development of IA, thus each category needs a separate evaluation. Diagnosis of IA in SOT recipients requires a high degree of awareness, because established diagnostic tools may not provide the same sensitivity and specificity observed in the neutropenic population. IA treatment relies primarily on mold-active triazoles, but potential interactions with immunosuppressants and other concomitant therapies need special attention. CONCLUSIONS: Criteria to assess response have not been sufficiently evaluated in the SOT population and CT lesion dynamics, and serologic markers may be influenced by the underlying disease and type and severity of immunosuppression. There is a need for well-orchestrated efforts to study IA diagnosis and management in SOT recipients and to develop comprehensive guidelines for this population.

Assessment of the Role of 1,3-ß-d-Glucan Testing for the Diagnosis of Invasive Fungal Infections in Adults.

Detection of 1,3-ß-d-glucan (BDG) in serum has been evaluated for its inclusion as a mycological criterion of invasive fungal infections (IFI) according to EORTC and Mycoses Study Group (MSG) definitions. BDG testing may be useful for the diagnosis of both invasive aspergillosis and invasive candidiasis, when interpreted in conjunction with other clinical/radiological signs and microbiological markers of IFI. However, its performance and utility vary according to patient population (hematologic cancer patients, solid-organ transplant recipients, intensive care unit patients) and pretest likelihood of IFI. The objectives of this article are to provide a systematic review of the performance of BDG testing and to assess recommendations for its use and interpretation in different clinical settings.

Budget Impact of Microbial Cell-Free DNA Testing Using the Karius® Test as an Alternative to Invasive Procedures in Immunocompromised Patients with Suspected Invasive Fungal Infections.

BACKGROUND: Invasive fungal infection is a major source of morbidity and mortality. The usage of microbial cell-free DNA for the detection and identification of invasive fungal infection has been considered as a potential alternative to invasive procedures allowing for rapid results. OBJECTIVE: This analysis aimed to assess the budget implications of using the Karius® Test in patients suspected of invasive fungal infection in an average state in the USA from a healthcare payer perspective. METHODS: The analysis used a decision tree to capture key stages of the patient pathway, from suspected invasive fungal infection to either receiving treatment for invasive fungal infection or being confirmed as having no invasive fungal infection. The analysis used published costs and resource use from a targeted review of the literature. Because of the paucity of published evidence on the reduction of diagnostic tests displaced by the Karius Test, the analysis used a 50% reduction in the use of bronchoscopy and/or bronchoalveolar lavage. The impact of this reduction was tested in a scenario analysis. RESULTS: The results of the analysis show that the introduction of the Karius Test is associated with a cost saving of US$2277 per patient; when multiplied by the estimated number of cases per year, the cost saving is US$17,039,666. The scenario analysis showed that the Karius Test only had an incremental cost of US$87 per patient when there was no reduction in bronchoscopy and bronchoalveolar lavage. CONCLUSIONS: The Karius Test may offer a valuable and timely option for the diagnosis of invasive fungal infection through its non-invasive approach and subsequent cost savings.

Invasive fungal disease in humans: are we aware of the real impact?

Despite the medical advances and interventions to improve the quality of life of those in intensive care, people with cancer or severely immunocompromised or other susceptible hosts, invasive fungal diseases (IFD) remain severe and underappreciated causes of illness and death worldwide. Therefore, IFD continue to be a public health threat and a major hindrance to the success of otherwise life-saving treatments and procedures. Globally, hundreds of thousands of people are affected every year with Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, Pneumocystis jirovecii, endemic dimorphic fungi and Mucormycetes, the most common fungal species causing invasive diseases in humans. These infections result in morbidity and mortality rates that are unacceptable and represent a considerable socioeconomic burden. Raising the general awareness of the significance and impact of IFD in human health, in both the hospital and the community, is hence critical to understand the scale of the problem and to raise interest to help fighting these devastating diseases.

Knowledge at what cost? An audit of the utility of panfungal PCR performed on bronchoalveolar lavage fluid specimens at a tertiary mycology laboratory.

The diagnostic utility and costs of panfungal PCR assays for invasive fungal disease (IFD) from bronchoalveolar lavage fluid (BALF) specimens are incompletely defined. In a retrospective audit, panfungal PCR results from 2014-2018 were matched with information on request forms and the registrar/microbiologist diary of clinical liaison. Identification of a single fungus other than a commensal was considered potentially clinically significant, and assessed for clinical relevance. Of 1002 specimens tested, an estimated 90% were requested in patients without clinical suspicion of IFD. There were 530 (52.9%) PCR-positive results of which 485/530 (91.5%) identified multiple fungal species or commensal fungi; 45 (8.5%) were clinically significant but only in 12 (1.2%) was panfungal PCR the sole diagnostic test leading to IFD diagnosis, all in immunocompromised patients with clinical suspicion of IFD. Costs of panfungal PCR tests averaged AUD 133 per test, or AUD 26,767/annum. However, the average cost-per-diagnosis achieved was AUD 15,978/annum. Limiting testing to patients at risk and with clinical suspicion of IFD, may save over AUD 13,383/annum (assuming 50-90% reduction in testing). The value-added utility of panfungal PCR on BALF is 1.2% (12/1002). We have since introduced pre-analytical stewardship limiting routine panfungal PCR testing of BALF to high-risk patients in our hospital.

Deep fungal infections diagnosed by histology in Uganda: a 70-year retrospective study.

Fungal infections cause substantial morbidity and mortality. However, the burden of deep fungal infections is not well described in Uganda. We aimed to estimate the burden and etiology of histologically diagnosed deep fungal infections in Uganda. We retrospectively reviewed histology reports at the Pathology Reference Laboratory, Department of Pathology, Makerere University, Kampala, Uganda from January 1950 to September 2019 to identify any reports that had a fungal infection as the diagnosis. Over the study period, 697 cases of deep fungal infections were identified with an average incidence of 0.73/100,000 persons per decade. There was a general decline in the number of cases detected. Median age of the cases was 28 years (IQR: 11-40) and majority (59%) were male. The age group of 0-10 years were the most affected. The foot was the most affected part of the body (26%). Deep mycoses identified include eumycetoma (32%), subcutaneous phycomycosis (26%), histoplasmosis (9.2%), chromoblastomycosis (4.6%), aspergillosis (3.3%), cryptococcosis (3.3%), blastomycosis (1.6%), subcutaneous mycosis (1.4%), dermatomycosis (1.3%), coccidioidomycosis (0.6%), mucormycosis (0.6%), and sporotrichosis (0.1%). Histoplasma was the commonest causative agent (9.2%) followed by Aspergillus (3.4%) and Cryptococcus (3.3%), while 81% of the fungal pathogens were not identified to genus/species level. Only 31% of the cases were diagnosed clinically as deep fungal infections. There is a substantial burden of deep fungal infections caused by multiple fungal pathogens in Uganda. There is need to build local capacity for mycology so as to improve on the index of clinical suspicion and diagnostic capabilities.

The cost-effectiveness of isavuconazole compared to the standard of care in the treatment of patients with invasive fungal infection prior to differential pathogen diagnosis in the United Kingdom.

Aims: To estimate the cost-effectiveness of isavuconazole compared with the standard of care, voriconazole, for the treatment of patients with invasive fungal infection disease when differential diagnosis of the causative pathogen has not yet been achieved at treatment initiation.Materials and methods: The economic model was developed from the perspective of the UK National Health Service (NHS) and used a decision-tree approach to reflect real-world treatment of patients with invasive fungal infection (IFI) prior to differential pathogen diagnosis. It was assumed that 7.8% of patients with IFI prior to differential pathogen diagnosis at treatment initiation actually had mucormycosis, and confirmation of pathogen identification was achieved for 50% of all patients during treatment. To extrapolate to a lifetime horizon, the model considered expected survival based on the patients' underlying condition. The model estimated the incremental costs (costs of drugs, laboratory analysis, hospitalization, and management of adverse events) and clinical outcomes (life-years (LYs) and quality-adjusted life-years (QALYs)) of first-line treatment with isavuconazole compared with voriconazole. The robustness of the results was assessed by conducting deterministic and probabilistic sensitivity analyses.Results: Isavuconazole delivered 0.48 more LYs and 0.39 more QALYs per patient at an incremental cost of £3,228, compared with voriconazole in the treatment of patients with IFI prior to differential pathogen diagnosis. This equates to an incremental cost-effectiveness ratio (ICER) of £8,242 per additional QALY gained and £6,759 per LY gained. These results were driven by a lack of efficacy of voriconazole in mucormycosis. Results were most sensitive to the mortality of IA patients and treatment durations.Conclusions: At a willingness to pay (WTP) threshold of £30,000 per additional QALY, the use of isavuconazole for the treatment of patients with IFI prior to differential pathogen diagnosis in the UK can be considered a cost-effective allocation of healthcare resources compared with voriconazole.

Invasive fungal disease in humans: are we aware of the real impact?

Despite the medical advances and interventions to improve the quality of life of those in intensive care, people with cancer or severely immunocompromised or other susceptible hosts, invasive fungal diseases (IFD) remain severe and underappreciated causes of illness and death worldwide. Therefore, IFD continue to be a public health threat and a major hindrance to the success of otherwise life-saving treatments and procedures. Globally, hundreds of thousands of people are affected every year with Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, Pneumocystis jirovecii, endemic dimorphic fungi and Mucormycetes, the most common fungal species causing invasive diseases in humans. These infections result in morbidity and mortality rates that are unacceptable and represent a considerable socioeconomic burden. Raising the general awareness of the significance and impact of IFD in human health, in both the hospital and the community, is hence critical to understand the scale of the problem and to raise interest to help fighting these devastating diseases.

Epidemiology and management burden of invasive fungal infections after autologous hematopoietic stem cell transplantation: 10-year experience at a European Pediatric Cancer Center.

BACKGROUND: Autologous hematopoietic stem cell transplantation (HSCT) carries risks of infectious morbidity. We analysed epidemiology and management burden associated with invasive fungal diseases (IFDs) in children and adolescents undergoing autologous HSCT. METHODS: In a retrospective, single-centre observational study, epidemiology and management burden associated with IFDs were analysed in all paediatric cancer patients who underwent autologous HSCT between 2005 and 2014. Clinical, radiographic and microbiological data were assessed up to 100 days post-transplant. The primary endpoint was the incidence of proven, probable and possible IFDs. Further endpoints included the use of systemic antifungal agents for prevention and management of IFDs; infectious and non-infectious comorbidities; and survival until day + 100. RESULTS: Of 95 patients (median age: 8 years; r, 0.75-20) underwent 103 HSCT procedures for solid tumours (92) or lymphoma (11). Primary antifungal prophylaxis was administered in 49 procedures (47.5%). No single case of proven/probable IFD was diagnosed. Nine cases (8.7%) fulfilled criteria of possible pulmonary mould infection and received treatment for a median of 14 days (r, 7-35). In an additional 12 procedures, empiric antifungal therapy with mould active agents was given for a median of 8 days (r, 3-105). Microbiologically documented non-fungal infections were observed in 17 procedures, and five patients were transferred to the ICU. There was one death from biopsy documented toxic endothelial damage at day 83 post-transplant. CONCLUSIONS: Autologous HSCT for solid tumours or lymphoma was associated with low morbidity from IFDs. However, utilisation of systemic antifungal agents for prevention and management of suspected IFDs was considerable.

Treatment of immunocompromised patients with suspected invasive fungal infections: economic analysis of diagnostic-driven versus empirical strategies in Algeria and Egypt.

Background: Invasive fungal infections (IFIs) in immunocompromised patients are associated with high mortality and treatment costs. Identifying appropriate, cost-effective treatment strategies is crucial to reduce the burden of IFIs. This economic assessment compared strategies for treating immunocompromised patients in Algeria and Egypt.Methods: We developed a decision analytic model incorporating clinical and cost inputs associated with a diagnostic-driven (DD) and standard empirical (SE) strategy. Costs and clinical outcomes were used to calculate incremental cost-effectiveness ratios (ICERs) per death avoided.Results: In both countries, 73.8 (DD) and 125.3 (SE) hypothetical patients per 1,000 received antifungal therapy; 73.8 (DD) and 32.7 (SE) had diagnosed IFIs. Survival at 180 days was similar between DD and SE strategies in Algeria (92.0% vs 91.6%) and Egypt (90.2% vs 90.0%). Total costs per patient were lower with the DD than SE strategy (Algeria: $839 vs $1,591; Egypt: $4,077 vs $4,717). ICERs indicated that the DD compared with SE strategy was associated with better clinical outcomes at a lower overall cost in both countries.Conclusion: Diagnostic-driven compared to empirical therapy may be cost-saving in Algeria and Egypt for the management of immunocompromised patients with persistent neutropenic fever, with no increase in mortality.

Next-generation sequencing for hypothesis-free genomic detection of invasive tropical infections in poly-microbially contaminated, formalin-fixed, paraffin-embedded tissue samples - a proof-of-principle assessment.

BACKGROUND: The potential of next-generation sequencing (NGS) for hypothesis-free pathogen diagnosis from (poly-)microbially contaminated, formalin-fixed, paraffin embedded tissue samples from patients with invasive fungal infections and amebiasis was investigated. Samples from patients with chromoblastomycosis (n = 3), coccidioidomycosis (n = 2), histoplasmosis (n = 4), histoplasmosis or cryptococcosis with poor histological discriminability (n = 1), mucormycosis (n = 2), mycetoma (n = 3), rhinosporidiosis (n = 2), and invasive Entamoeba histolytica infections (n = 6) were analyzed by NGS (each one Illumina v3 run per sample). To discriminate contamination from putative infections in NGS analysis, mean and standard deviation of the number of specific sequence fragments (paired reads) were determined and compared in all samples examined for the pathogens in question. RESULTS: For matches between NGS results and histological diagnoses, a percentage of species-specific reads greater than the 4th standard deviation above the mean value of all 23 assessed sample materials was required. Potentially etiologically relevant pathogens could be identified by NGS in 5 out of 17 samples of patients with invasive mycoses and in 1 out of 6 samples of patients with amebiasis. CONCLUSIONS: The use of NGS for hypothesis-free pathogen diagnosis from contamination-prone formalin-fixed, paraffin-embedded tissue requires further standardization.

Cost analysis of bronchoalveolar lavage and respiratory tract biopsies in the diagnosis and management of suspected invasive fungal infection in children with cancer or who have undergone stem cell transplant.

BACKGROUND: Identification of an organism is the gold standard for the diagnosis of fungal infection; however, we have previously shown that invasive procedures infrequently lead to a change in management in children with cancer or who have undergone stem cell transplant with suspected respiratory tract invasive fungal infection (RT-IFI). There is also a paucity of data on the cost of RT-IFI in this population. We therefore compared the costs of RT-IFI diagnosed based on CT scan alone versus those who underwent a bronchoalveolar lavage (BAL) or respiratory tract biopsy (RTB). PROCEDURE: We collected cost data on patients at a single center undergoing chemotherapy or who were post-hematopoietic stem cell transplant (HSCT) and were suspected of having RT-IFI between 2007 and 2012. Cost data were included for 14 days from the day of their diagnostic CT scan or procedure. RESULTS: Cost data were available for 76 patients. Thirty-six patients were diagnosed with suspected RT-IFI based on CT only, and 40 patients underwent BAL or RTB. Costs related to chest X-rays (CXRs), inpatient/intensive care unit (ICU) beds, anesthesia, operating room (OR) time, and procedures were significantly higher in the BAL/RTB group versus CT scan group (all P < 0.01). Costs related to CT scans were significantly higher in the CT scan group (P = 0.0002). Overall costs were significantly higher for patients who underwent BAL or RTB versus CT scan only (P < 0.0001). CONCLUSION: Our previous data showed that BAL and RTB infrequently led to a change in management in this population. We now demonstrate that this strategy is costly as well.

Host-Derived Biomarkers for Risk Assessment of Invasive Fungal Diseases.

Invasive fungal diseases are major complications associated with the treatment of hematologic malignancies. The integration of host-derived biomarkers into clinical processes to predict the risk and progression of fungal disease is a promising approach in immunocompromised patients. Recent insights into human antifungal immunity have highlighted the remarkable influence of host genetics in modulating susceptibility to infection. In this chapter, we describe protocols to examine human genetic variation and to assess its functional consequences using the pattern recognition receptor PTX3 as an example.

Optimization of voriconazole dosage regimen to improve the efficacy in patients with invasive fungal disease by pharmacokinetic/pharmacodynamic analysis.

Invasive fungal disease (IFD) is a significant cause of morbidity and mortality in hospitalized patients. To maximize the efficacy of voriconazole treatment, the study established the relationship between voriconazole pharmacokinetic/pharmacodynamic (PK/PD) and probability of response and optimized voriconazole dosage regimen in patients with IFD based on Monte Carlo simulation. Forty-four patients proven with IFD were involved in this study. Among them, the overall cure rate was 75% (33/44) and there was a significant difference between Cmin /MIC values in patients with lack of response (n = 11) and those with successful response (n = 33) (mean value: 1.91 vs. 11.33; P < 0.05). Logistic regression model showed a high correlation between voriconazole Cmin /MIC ratio and clinical response (P = 0.044, OR = 1.349). According to Monte Carlo simulation results under different voriconazole dosing regimens, we could draw a conclusion that 200 mg voriconazole administered intravenously or orally twice daily for Candida infections and 300 mg administered orally or with 200 mg administered intravenously twice daily for Aspergillus infections were rational, which could achieve a value of the cumulative fraction of response >90%. This study built the relationship between voriconazole PK/PD and clinical response and obtained the reasonable empirical dosage regimen, which can be used to customize individual dosage regimen and improve the efficacy of voriconazole treatment.