Diagnostic Value Of Bronchoalveolar Lavage Fluid Galactomannan Standardized By Internal Reference For Invasive Pulmonary Aspergillosis

Background: To establish the optimal cut-off value of galactomannan in bronchoalveolar lavage fluid(BALF GM)for invasive pulmonary aspergillosis(IPA)diagnosis.To investigate which substance to choose as internal reference of BALF GM and how to standard,and whether the BALF GM results after standardizing can improve the clinical diagnostic efficiency for invasive pulmonary aspergillosis(IPA).Methods: A total of 256 inpatients' BALF specimens were collected from the first Affiliated Hospital of Chongqing Medical University between May 2018 and August 2019,who were suspected aspergillosis infection.Galactomannan,potassium,urea and albumin tests were performed in their BALF samples.According to histopathology,microbiological results,clinical symptoms and characteristics,host factors and other data,56 cases and 200 cases were divided into IPA group and non-IPA group,respectively.ROC curve was generated to determine the cut-off value,and compared the clinical diagnostic efficiencies ofstandardized and non-standardized BALF GM tests for IPA.Results: The standardized and non-standardized BALF GM results were both significantly different between two groups(P<0.05).ROC curve showed that,an optimal cut-off value of non-standardized BALF GM is0.645 yielded a sensitivity of 71.4% and a specificity of 73.0%,and the area under the curve(AUC)was 0.757(P<0.001).After standardizing by K+,UREA,and ALB,the cut-off values are 0.605,1.615,0.68,and the areas under the curve were 0.768,0.709,0.744,respectively(All P<0.001).The sensitivities were 73.2%,73.2%,74.2%,and the specificities were74.5%,62.5%,74.8%,respectively.Serum GM used the unified cut-off value 0.5,with a sensitivity of 10.7% and a specificity of 95.5%.Conclusion: With a cut-off value of 0.645,the non-standardized BALF GM test has the best diagnostic efficiency for IPA and was higher than serum GM test.And the diagnostic efficiency of BALF GM after being standardized by K+ was better than that of non-standardized BALF GM(P<0.001).