E. Geoffrey Playford, Jeffrey Lipman, Michael Jones, Anna F. Lau, Masrura Kabir, Sharon C.-A. Chen, Deborah J. Marriott, Ian Seppelt, Thomas Gottlieb, Winston Cheung, Jonathan R. Iredell, Emma S. McBryde, Tania C. Sorrell

 Delayed antifungal therapy for invasive candidiasis (IC) contributes to poor outcomes. Predictive risk models may allow targeted antifungal prophylaxis to those at greatest risk.  A prospective cohort study of 6,685 consecutive non-neutropenic patients admitted to seven Australian ICUs ≥72 hours was performed. Clinical risk factors for IC occurring prior to and following ICU admission, colonisation with Candida spp on surveillance cultures from three sites assessed twice-weekly, and the occurrence of IC ≥72 hours following ICU admission or ≤72 hours following ICU discharge were measured. From these parameters, a risk predictive model for the development of ICU-acquired IC was then derived.  Ninety-six patients (1.43%) developed ICU-acquired IC. A simple summation risk predictive model using the ten independently significant variables associated with IC demonstrated overall moderate accuracy (area under receiver operator curve, 0.81). No single threshold score could categorise patients into clinically useful high- and low-risk groups. However, using two threshold scores, three patient cohorts could be identified; those at high risk (score ≥6, 4.8% of total cohort, positive predictive value, 11.7%), those at low risk (score ≤2, 43.1%, 0.24%), and those at intermediate risk (score 3-5, 52.1%, 1.46%).  Dichotomisation of ICU patients into high- and low-risk groups for IC risk is problematic. Categorising patients into high, intermediate, and low risk groups may more efficiently target early antifungal strategies and utilisation of newer diagnostic tests.