Diagnostic accuracy of lung ultrasound for pulmonary tuberculosis in outpatients from Papua New Guinea, a resource-limited setting

Objectives to evaluate the diagnostic accuracy of lung ultrasound (LUS) for pulmonary tuberculosis (PTB) in Papua New Guinea (PNG). Methods Prospective observational study including outpatients with presumptive PTB (cough ≥2 weeks) attending a TB clinic in Port Moresby, PNG. Participants underwent clinical assessment, GeneXpert Ultra-MTB/RIF, chest X-ray (CXR), and LUS. Diagnostic accuracy of LUS findings was assessed using GeneXpert as reference standard. Accuracy of CXR and agreement with LUS were also evaluated. A LUS scoring system was developed using LASSO logistic regression. Results Between May 2022 and May 2023, 512 participants were enrolled, and 488 with GeneXpert were included in the analyses. Median age was 30 [inter-quartile range 23-44], and 55% were male. GeneXpert was positive in 149 (30.5%). Combined LUS findings sensitivity was 92.6% (95% confidence intervals [CI] 90.1-95.1) and specificity 46.8% (95% CI: 42.1-51.5). CXR sensitivity was 91.3% (95% CI: 86.6-93.9) and specificity 65.1% (95% CI: 60.7-69.6). Agreement between LUS and CXR was moderate (kappa = 0.48). The LUS score achieved 82.8% sensitivity and 84.2% specificity. Conclusion LUS demonstrates high sensitivity for detecting PTB, equivalent to CXR, but low specificity. LUS may have diagnostic value, particularly where radiography is unavailable. The scoring system that showed higher specificity should be validated in future studies.