Classification of invasive fungal disease in patients with acute myeloid leukaemia

Invasive fungal diseases (IFD) are a major cause of morbidity and mortality in patients with acute myeloid leukaemia (AML). Their incidence has risen dramatically in recent years. The diagnosis of IFDs remains difficult, even if the European Organisation for the Research and Treatment of Cancer (EORTC)/Mycosis Study Group (MSG) criteria are applied for study purposes to classify the likelihood of these infections. These criteria have been developed for clinical trials, and their relevance in clinical settings outside a clinical trial remains unknown. We evaluated the impact of the EORTC/MSG criteria and a modification thereof for clinical purposes in patients with AML. We retrospectively analysed 100 AML patients for the occurrence of IFD. First, EORTC/MSG criteria were applied to classify the patients. Second, a modified version of these criteria already used in clinical trials was used to re-classify the patients. Fifty-seven patients developed an invasive fungal infection. Following the original criteria, 43% were classified as 'possible' IFD, whereas 7% each were classified as 'probable' and 'proven' IFD. After application of the modified criteria, only 9% of the patients remained 'possible' IFD, whereas 41% were 'probable'. The occurrence of 'proven' cases was not altered by the modification and thus remained 7%. The application of modified criteria for the classification of IFD in AML patients leads to a considerable shift from 'possible' IFD (according to conventional EORTC criteria) towards 'probable' IFD. Nevertheless, neither the old EORTC criteria nor their modification was designed for use in clinical practice. As this study underscores the uncertainty in the diagnosis of IFD, the need for a clinically applicable classification is obvious.