Two Strategies for Managing Invasive Aspergillosis: A Decision Analysis

We devised a diagnostic approach based on screening plasma for an Aspergillus antigen with use of a sandwich enzyme-linked immunosorbent assay (ELISA), thoracic computed tomographic scanning, and radionuclide imaging for managing patients at risk for invasive aspergillosis. We used a decision analytic model to compare this alternative strategy with the conventional strategy, which relies only on the presence of clinical symptoms, persistent fever, and chest roentgenographic findings. Use of the alternative strategy reduced the number of patients who would receive antifungal treatment empirically, but this strategy was more expensive. The specificity of the sandwich ELISA had a significant impact on cost, but the sensitivity did not. A 13% prevalence of infection resulted in equal costs for both strategies. As much as 43.3% of the patients treated empirically could be given liposomal amphotericin B (L-AmB) before the conventional strategy became the most expensive. The costs of the alternative strategy were less than those of the conventional strategy when >5.3% of all patients, irrespective of strategy, were treated with L-AmB.