Evaluation of non-invasive diagnostic tests for

Background: Accurate and timely identification of Methods: We conducted a retrospective study of adult patients hospitalized for community-acquired pneumonia (CAP) from January 2024 to October 2024. All enrolled patients underwent bronchoalveolar lavage fluid metagenomic next-generation sequencing (BALF-mNGS) and had received at least one of two non-invasive tests (NAAT or serum IgM antibody assays). The sensitivity and specificity of NAAT and serum IgM antibody assays were calculated against the final diagnosis. A non-inferiority test was used to determine whether the sensitivity of NAAT or serum IgM antibody assays was not inferior to that of mNGS. Results: Among 594 patients included in the analysis, 60 were diagnosed with MPP based on a composite reference standard that included laboratory testing results and adjudication by two senior clinicians in accordance with clinical and radiological findings. The sensitivity and specificity of NAAT were 74.1% and 99.3%, respectively, while those of serum IgM antibody assays were 23.6% and 98.0%. McNemar's test revealed a statistically significant difference in sensitivity between mNGS and the two non-invasive tests (NAAT and serum IgM antibody assays) ( Conclusion: In clinical practice, a positive result from either NAAT or serum IgM antibody assays can serve as reliable adjunct evidence for diagnosing MPP. However, in cases with a high clinical suspicion of MPP, negative results from both methods are not sufficient to rule out the diagnosis. For MPP, mNGS remains the most effective diagnostic method compared to non-invasive testing alternatives.