The misleading effect of serum galactomannan testing in high-risk haematology patients receiving prophylaxis with micafungin

OBJECTIVES

To investigate the performance of the routine serum galactomannan (sGM) assay in the diagnosis of invasive aspergillosis (IA) in high-risk haematology patients receiving prophylaxis with micafungin.

METHODS

Retrospective study including all haematological patients who received prophylaxis with micafungin during high-risk IA episodes (neutropenic patients after chemotherapy for acute myeloid leukaemia/myelodysplastic syndrome; allogeneic haematopoietic stem-cell transplantation during early neutropenic phase or graft-versus-host disease requiring high prednisone doses) and for whom at least one sGM result was available. Episodes were classified as follows: true-positive (positive GM in the context of IA), false-positive (positive GM result in patients who had no evidence of IA), true-negative (negative GM test results and no IA), or false-negative (negative GM test in the context of IA). Non-evaluable patients were excluded.

RESULTS

Among 146 evaluable episodes, four were true-positive in the context of probable breakthrough IA (incidence of breakthrough IA, 2.7%); 111/146 high-risk episodes (76%) were considered true-negative and 31/146 (21.2%) were considered false-positive. No false-negative episodes were detected. All but one of the false-positive episodes were detected in surveillance GM tests, leading to high-resolution CT scans in eight cases (8/31; 25.8%), all of which were negative. The positive predictive and negative predictive values of sGM for surveillance and diagnostic approaches were 3.2% (1/31) and 100% (110/110) and 75% (3/4) and 100% (1/1), respectively.

CONCLUSIONS

Surveillance of asymptomatic patients receiving prophylaxis with micafungin using sGM is unnecessary, because the results are either negative or false-positive. However, sGM remains useful in the diagnosis of breakthrough IA in symptomatic patients during prophylaxis.

Delphi-based study and analysis of key risk factors for invasive fungal infection in haematological patients

OBJECTIVE

Mortality caused by invasive fungal infections due to filamentous fungi (IFI-FF) is high. Predisposing factors to IFI-FF are multiple and should be stratified. The objective of this study was to identify key risk factors for IFI-FF in onco-haematological patients in different clinical settings.

METHODS

Prospective national Delphi study. Risk factors for IFI-FF in patients with onco-haematological diseases were identified by a systematic review of the literature. An anonymous survey was sent by e-mail to a panel of experts. A key risk factor was defined when at least 70% of the surveyed participants assigned a "maximal" or "high" risk.

RESULTS

In allogenic stem cell transplantation, 18 of the 42 risk factors analyzed were classified as key risk factors, including neutropenia, previous IFI-FF, grade III/IV acute or extensive chronic graft-versus-host disease (GVHD), umbilical cord blood transplantation, HLA mismatching transplantation, graft failure, absence of HEPA filters, absence of laminar air flow, diagnosis of acute myeloid leukaemia, haploidentical transplantation, anti-TNF-α drugs, alemtuzumab, anti-thymocyte globulin, immunosuppressive prophylaxis for GVHD, lymphocytopenia, cytomegalovirus infection, and proximity to construction areas. In acute leukaemia/myelodysplastic syndrome (AL/MDS), 7 of 25 risk factors were defined as key risk factors, including neutropenia, consolidation therapy without response, induction therapy, antifungal prophylaxis with azoles, proximity to construction areas, and absence of HEPA filters. In lymphoma/multiple myeloma (MM), the five key risk factors among 21 analyzed were use of steroids, neutropenia, progressive disease, anti-CD52 therapies, and proximity to construction areas.

CONCLUSIONS

The Delphi method was useful for the classification and stratification of risk factors for IFI-FF in patients with onco-haematological diseases. Identifying key risk factors will contribute to a better management of IFI-FF in this group of patients at high or changing risk.

Antifungal stewardship in a tertiary-care institution: a bedside intervention

Antifungal stewardship (AFS) programmes are needed in tertiary-care hospitals. Our aim is to describe a bedside non-restrictive AFS programme, and to evaluate its economic impact. During the first year of the AFS a bundle of non-interventional measures were implemented. During the second year an infectious diseases specialist visited 453 patients receiving candins, liposomal amphotericin B, voriconazole or posaconazole. Monthly costs were studied with an interrupted time series (ITS) analysis. The main prescribing departments were haematology (35%), medical departments (23%), and intensive care units (20%). Reasons to start antifungal therapy were: targeted therapy (36%), prophylaxis (32%), empirical therapy (20%) and pre-emptive therapy (12%). At the initial visit, diagnostic advice was provided in 40% of cases. The most common therapeutic recommendations were to de-escalate the antifungal drug (17%) or to suspend it (7%). Annual total antifungal expenditure was reduced from US$3.8 million to US$2.9 million over the first 2 years, generating net savings of US$407,663 and US$824,458 per year after considering the cost of additional staff required. The ITS analyses showed a significant economic impact after the first 12 months of the intervention (p 0.042 at month 13), which was enhanced in the following 24 months (p 0.006 at month 35). The number of defined daily doses decreased from 66.4 to 54.8 per 1000 patient-days. Incidence of candidaemia was reduced from 1.49 to 1.14 (p 0.08) and related mortality was reduced from 28% to 16% (p 0.1). A collaborative and non-compulsory AFS program based on bedside intervention is an efficacious and cost-effective approach that optimizes the use of AF drugs.

Early peripheral blood and T-cell chimerism dynamics after umbilical cord blood transplantation supported with haploidentical cells

Single-unit umbilical cord blood (CB) SCT is limited by low total nucleated cell (TNC) dose. Co-infusion of CD34+ cells from a third party HLA-mismatched donor, known as dual or haplo-cord transplant, reduces the period of post-transplant neutropenia and related complications. The aim of this study was to analyze the value of early post-transplant peripheral blood (PB) and T cell chimerism after 28 dual transplants regarding CB engraftment. Cumulative incidence of myeloid engraftment at 30 days was 93% with a median time to engraftment of 14 days (10-29). Patients who developed CB graft failure (n=5) showed very low percentages of CB cells on days +14, +21 and +28 with decreasing dynamics. On the other hand, percentages of CB cells in patients who achieved CB engraftment increased over time. Interestingly, such patients showed two distinct chimerism dynamics in PB, but all of them showed a predominance of CB T cells early after SCT with increasing dynamics over time. Early post-transplant chimerism dynamics in PB and T cells predicts CB graft failure enabling rapid therapeutic measures to be applied. On the other hand, early increasing percentages of CB T cells correlates with ultimate CB engraftment.