A Risk Prediction Score for Invasive Mold Disease in Patients with Hematological Malignancies

BACKGROUND: A risk score for invasive mold disease (IMD) in patients with hematological malignancies could facilitate patient screening and improve the targeted use of antifungal prophylaxis. METHODS: We retrospectively analyzed 1,709 hospital admissions of 840 patients with hematological malignancies (2005-2008) to collect data on 17 epidemiological and treatment-related risk factors for IMD. Multivariate regression was used to develop a weighted risk score based on independent risk factors associated with proven or probable IMD, which was prospectively validated during 1,746 hospital admissions of 855 patients from 2009-2012. RESULTS: Of the 17 candidate variables analyzed, 11 correlated with IMD by univariate analysis, but only 4 risk factors (neutropenia, lymphocytopenia or lymphocyte dysfunction in allogeneic hematopoietic stem cell transplant recipients, malignancy status, and prior IMD) were retained in the final multivariate model, resulting in a weighted risk score 0-13. A risk score of < 6 discriminated patients with low (< 1%) versus higher incidence rates (> 5%) of IMD, with a negative predictive value (NPV) of 0.99, (95% CI 0.98-0.99). During 2009-2012, patients with a calculated risk score at admission of < 6 had significantly lower 90-day incidence rates of IMD compared to patients with scores > 6 (0.9% vs. 10.6%, P <0.001). CONCLUSION: An objective, weighted risk score for IMD can accurately discriminate patients with hematological malignancies at low risk for developing mold disease, and could possibly facilitate “screening-out” of low risk patients less likely to benefit from intensive diagnostic monitoring or mold-directed antifungal prophylaxis.