The Value of the Galactomannan Test in Diagnosing COVID-19-Associated Pulmonary Aspergillosis: A Review

COVID-19-associated pulmonary aspergillosis (CAPA) is a complication of COVID-19. Galactomannan (GM) is a non-invasive test used to diagnose invasive aspergillosis. We collected the existing studies on the diagnostic value of GM to determine a GM level for predicting CAPA. All articles on the value of GM in CAPA diagnosis published until November 2023 were reviewed. The main databases were searched using the following keywords: "aspergillus", "aspergillosis", "SARS-CoV-2", "COVID", "2019 ncovnCOV", "novel coronavirus", "COVID-19", "galactomannan", and "CAPA". Studies with reported levels of serum or BAL GM were included. Patients were classified into two groups: non-confirmed and proven aspergillosis. Finally, the receiver operating characteristic (ROC) curve analysis was used to determine a GM level to predict the likelihood of CAPA. A total of 26 articles were selected, of which 239 patients were included. A count of 123 patients (50%) were in the non-confirmed group and 124 (50%) patients were proven. The median serum GM was 0.51 in the non-confirmed group and 0.47 in the proven group (p= 0.73). The level of GM in BAL fluid was 0.10 in the non-confirmed and 2.80 in the proven group, which was statistically different (p<0.001). With 81.3 % sensitivity and 79.5% specificity, the BAL GM cut-off was 1.01 ODI. The results showed that BAL GM ≥1.01 can be used to predict CAPA. Serum GM did not show any predictive value in diagnosing CAPA. However, BAL GM level can be a reliable diagnostic test in patients with CAPA.