Validation of an Index of Neutropenia (D-index) in Febrile Neutropenic Cancer Patients
Validation of an Index of Neutropenia (D-index) in Febrile Neutropenic Cancer Patients
The main objective of this study is to test prospectively the performance of an algorithm
 stratified by an index based on neutrophil counts in association with galactomannan assay and
 image tests to start an antifungal early therapy (empirical/preemptive) in neutropenic
 patients. Ths specific objectives are to determine the overall incidence of invasive fungal
 infections, use of antifungal agents, duration of hospitalization and mortality in this
 cohort, and to evaluate if this strategy is associated with a reduction in the expected use
 of antifungal agents if a classical empiric antifungal strategy was used, without an increase
 in the incidence of invasive fungal infections.

 This is a prospective, non randomized, non comparative study. Patients aged ≥ 18 years are
 eligible if they have acute leukemia, myelodysplasia or other baseline disease submitted to
 chemotherapy or to allogeneic stem cell transplantation with an expected duration of
 neutropenia (neutrophil count <500cells/mm³) of at least 10 days. Exclusion criteria are
 patients with and a past history of or invasive mold infection and those who do not want to
 participate. The study has no comparator arm. However, the investigators intend to determine
 if the algorithm based on the D-index would result in a 50% reduction in the use of
 antifungal agents, if all patients with persistent fever and neutropenia received empiric
 antifungal therapy. Based on our database of ~2,000 episodes of febrile neutropenia, 36% of
 patients had persistent fever between days 4 and 7 of antibiotics and would receive empiric
 antifungal therapy. A total of 105 patients will be needed to demonstrate a 50% reduction in
 antifungal use if the investigators compared this cohort with a matched control historical
 cohort (alpha = 5%, beta = 20%).
Neutropenia is a major risk factor for invasive fungal infections, particularly those caused
 by moulds, such as Aspergillus spp., Fusarium spp. and the Zygomycetes. Among neutropenic
 patients, these invasive mould infections (IMI) occur almost exclusively in patients with
 profound neutropenia (<100 neutrophils/mm3) lasting more than 10-15 days [1-3]. Empiric
 antifungal therapy is considered standard of care in patients with persistent or recurrent
 fever and neutropenia. However using fever as the sole criterion for starting empiric
 therapy, a significant number of patients will receive antifungal therapy unnecessarily,
 particularly among recipients of fluconazole prophylaxis, because persistent fever in these
 patients is commonly due to various factors, such as uncontrolled occult bacterial infection,
 viral infection, drug fever and others [4].

 An alternative to empiric antifungal therapy is the preemptive treatment. In this strategy,
 other markers (such as serology, radiology and clinical data) are added to persistent fever
 [5,6]. One problem of such strategy is that the biomarkers currently in use (galactomannan
 [GM], 1,3-beta-D-glucan and PCR) have high sensitivity. If one of these markers is used to
 trigger the start of antifungal therapy, still a considerable number of patients will use
 antifungal agents unnecessarily. However, a positive biomarker early in the course of
 neutropenia most likely represents a false-positive result. By contrast, a positive biomarker
 test late in the course of neutropenia is more likely to be a true positive. A problem is
 that no cutoff value of duration of neutropenia is validated to help clinicians to identify
 these 2 possibilities.

 A clinical parameter that evaluated the dynamics of neutropenia, combining intensity and
 duration, could be a good tool to identify patients at high risk for IMI. This tool could be
 used to stratify patients, helping clinicians to select appropriate candidates for early
 antifungal therapy (empiric or preemptive) in persistently febrile neutropenic patients. We
 developed an index (called D-index) that uses data from white blood cell counts (WBC), and
 combines intensity and duration of neutropenia. This index was tested in patients with acute
 myeloid leukemia, and showed a good discriminatory performance in identifying patients with
 IMI and without IMI. A cutoff was derived, and showed good sensitivity, specificity and a
 very high negative predictive value (97 to 99%) [7]. The high negative predictive value of
 this index is very similar to that obtained with GM and 1,3-beta-D-glucan in febrile
 neutropenic patients [8,9]. With this regard, the D-index could be of help to assess the
 pre-test probability of IMI and help to interpret the results of positive serum GM and / or
 1,3-beta-D-glucan: patients with low values of D-index would be best interpreted as having
 false-positive results of these tests. Similarly, positive biomarkers in the presence of a
 high D-index would be more likely to be true positives, since the combination of different
 tests may increase their positive predictive value.

 This is a prospective cohort study. The study will be submitted to the IRB and written
 informed consent will be obtained from all participants.

 Patients aged ≥ 18 years are eligible if they have acute leukemia, myelodysplasia or other
 underlying hematologic malignancy receiving chemotherapy with an expected duration of
 neutropenia (<500/mm3) >10 days. This includes allogeneic (but not autologous) hematopoietic
 stem cell transplantation. Patients with past history of IMI will be excluded, since for
 these patients secondary prophylaxis is advised.

 Patients will be enrolled at initiation of chemotherapy and no later than 48h from the first
 day of neutropenia. The same patient will be able to be enrolled more than once, but if he
 develops IMI, he will be no longer eligible for a subsequent inclusion. All patients will
 receive antimicrobial prophylaxis with fluconazole (400mg daily). Chest imaging (X-ray or CT
 scan) will be performed at the enrollment. During the period of neutropenia induced by
 chemotherapy/ conditioning regimen, patients will be surveyed for the development of fever
 and will have the D-index calculated day by day. At the time of febrile neutropenia, at least
 2 blood cultures will be collected. Other microbiologic exams will be obtained if clinically
 indicated. The patients will then receive a broad-spectrum β-lactam antibiotic (cefepime).
 Vancomycin will be added for patients who have clinically suspicion of catheter-related
 infection or a blood culture yielding Gram-positive bacteria not yet identified. Serum will
 be obtained 3 times a week for Aspergillus GM assay (Platelia Aspergillus; Bio-Rad) and
 Aspergillus sp. PCR (in-house real time qualitative and quantitative PCR). A positive GM will
 be defined as an index ≥ 0.5.

 In case of persistent fever or a new fever, blood cultures will be collected and CT scans of
 the chest and the sinuses will be performed. Results of GM will be checked and the patients
 will be stratified according to the D-index as high, moderate or low risk for IMI. Based on
 this analysis, antifungal therapy (caspofungin 70 mg day 1 and 50 mg/d thereafter) will be
 started. In high risk patients (D index ≥ 5,800), the trigger for anti mold treatment will be
 the presence of any image on CT scan or any positive GM. In the moderate risk (D-index
 between 3,000 and 5,800), the trigger will be the presence of persistence of a positive GM in
 consecutive tests. In this stratum, chest CT scan will be defined as indicative of antifungal
 initiation only in the presence of one of the following: nodules > 1 cm, with or without halo
 sign, wedge-shaped images, or cavitation. For low-risk patients (D-index <3,000), antifungal
 treatment will be started only in the persistence of positive GM result in consecutive tests.
 In situations in which antifungal treatment is not started, reassessment of these parameters
 will be made at least twice a week with the evaluation of the D-index and biomarkers, and
 once a week with CT scans. In patients with lung infiltrates, a bronchoalveolar lavage (BAL)
 will be taken, provided the patient is not hypoxemic or severely thrombocytopenic and
 refractory to platelet transfusions. In the presence of findings in sinuses CT scans
 suggestive of sinusitis, nasal endoscopy will be performed. BAL and sinus aspiration samples
 will be processed for direct examination, culture, GM and Aspergillus PCR. Other diagnostic
 procedures will be performed when clinically indicated. Autopsy will be performed in all
 fatal cases after family authorization. Invasive fungal infection will be classified
 according to the Revised Definitions from the European Organization for Research and
 Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute
 of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group [10].

 To assess the performance of risk stratification based on the D-index, the overall use of
 antifungal treatment (al well as stratified by D-index) will be recorded, and reported by
 descriptive statistics. The outcome of each risk stratus (low, moderate and high) will be
 compared regarding: incidence of suspected and documented mold infection, use of anti mold
 therapy, duration of hospitalization and death rate. In addition, the proportion of patients
 receiving early antifungal treatment will be compared with empiric antifungal use in a
 historical matched-control cohort. Patients from the 2 cohorts will be compared using
 propensity score procedure. Propensity score analysis attempts to identify patients who are
 similar except for their treatment. The analysis will be performed as follows: first, the
 probability of any patient in the database to receive empiric antifungal therapy will be
 estimated using a multivariate logistic regression model that incorporates baseline
 characteristics, underlying diseases and co-morbidities. Next, we will match from the 2
 cohorts patients with the nearest propensity score (the score generated by the multivariate
 equation)[10].

 Based on our database of ~2,000 episodes of febrile neutropenia, 36% of patients had
 persistent fever between days 4 and 7 of antibiotics and would receive empiric antifungal
 therapy. A total of 105 patients would be needed to demonstrate a 50% reduction in antifungal
 use if we compared this cohort with a matched control historical cohort (alpha = 5%, beta =
 20%).
Inclusion Criteria:

 -  age 18 years or more

 -  acute myeloid leukemia or myelosysplasia undergoing induction remission or
 consolidation therapy

 -  allogeneic stem cell transplant recipients

 Exclusion Criteria:

 -  prior invasive mould infection