Diagnostic Performance and Cost-Effectiveness of BALF mNGS in Older Adults with Pulmonary Infections

Pulmonary infections in elderly patients cause high morbidity and mortality. Conventional culture has low sensitivity and slow turnaround, delaying targeted therapy. Metagenomic next-generation sequencing (mNGS) is an emerging technology, but its diagnostic performance and cost-effectiveness are unclear. This study therefore aims to evaluate its diagnostic performance compared to conventional culture in older adults with pulmonary infections and to assess its cost-effectiveness.

From March 2020 to March 2023, 522 patients (aged 55-69 years) diagnosed with pulmonary infections were enrolled at Peking University Shenzhen Hospital. Of these, 168 patients underwent simultaneous mNGS and conventional culture testing using bronchoalveolar lavage fluid (BALF) samples, while the remaining 354 patients received culture testing alone. Pathogen detection results were compared to assess the diagnostic performance of mNGS versus traditional culture methods. Additionally, cost-effectiveness analyses of the two diagnostic strategies-as well as the impact of mNGS testing timing post-admission-were conducted in the overall cohort and across stratified subgroups.

Among the 168 patients who underwent both tests, mNGS identified a greater diversity and abundance of microorganisms than culture (overall detection: 89.88% vs. 26.79%; pathogen detection: 67.86% vs. 18.45%, p < 0.001). mNGS testing yielded a net economic benefit of 1202.70 CNY per patient overall and 3831.15 CNY among pathogen-positive cases. Delaying mNGS testing tended to be associated with increased hospitalization length of stay (LOS) and costs, with the most pronounced difference observed around 6 days after admission (p < 0.001). Early mNGS testing (within 6 days of admission) provided a net benefit of 6346.00 CNY.

BALF-based mNGS showed higher positivity rates and a broader pathogen detection spectrum compared to conventional culture methods in this study. Early implementation of mNGS shows strong potential to guide the treatment of pulmonary infections and reduce healthcare costs for elderly and aging patients.