Usefulness of sequential Aspergillus galactomannan antigen detection combined with early radiologic evaluation for diagnosis of invasive pulmonary aspergillosis in patients undergoing allogeneic stem cell transplantation

Background. Early diagnosis of invasive pulmonary aspergillosis (IPA) is important as prompt treatment with antifungal drugs may increase patient survival. Our study investigated the efficiency of routine testing of the Aspergillus galactomannan antigen (AGA) test in combination with chest CT scans for IPA diagnosis. Patients and Methods. From February 2002 to June 2004, 74 hemato-oncologic patients undergoing allogeneic stem cell transplantation were prospectively studied with serum AGA twice weekly from admission until death or discharge and weekly afterward when possible. Chest CT scans were performed when fever of unknown origin had lasted beyond 3 days of antibacterial therapy. Results. Seven patients were classified with possible IPA and two patients, proven IPA. Fourteen patients showed positive results for AGA (OD index >= 1.0 on two subsequent sera). The sensitivity and specificity of the test were 100% and 93%, respectively; the positive and negative predictive values were 64% and 100%, respectively. All patients with possible/proven IPA showed abnormal CT signs; in four cases, imaging signs followed AGA positivity (median 5 days), whereas in five cases they preceded serologic positivity (median, 8 days). In the nine patients with IPA, antifungal therapy was promptly instituted, including lipid formulations of amphotericin B (n = 5) or caspofungin (n = 4). In only two of the nine patients (22%) with IPA, the primary cause of death was fungal infection. Conclusions. The combination of AGA detection and early chest CT scans might be considered useful tools to detect minimal changes of IPA. Based on these findings, aggressive antifungal therapy should be initiated.