The incremental value of bronchoalveolar lavage for the diagnosis of pulmonary tuberculosis in a high-burden urban setting

Objectives We prospectively evaluated the use of bronchoalveolar lavage fluid (BALF) specimens to assess their added incremental value to pulmonary tuberculosis (TB) diagnostic strategies used currently in a high-burden urban setting in China. Methods A prospective study was conducted of patients with presumptive pulmonary TB registered at the Fifth Hospital of Suzhou between March 2018 and July 2018. BALF samples from patients with initial Xpert-negative sputum results were tested to diagnose TB. Results Of 440 participants, 316 (71.8%) were initially diagnosed with TB from sputum, including 245 (55.7%) definitive TB cases based on a positive culture and/or Xpert result(s) and 71 (16.1%) positive cases based on clinical diagnosis. Of 153 patients with initial positive cultures, a significantly higher proportion were confirmed as TB-positive using Xpert (94.1%) versus smear microscopy (45.8%, P < 0.01). Xpert testing of BALF from 182 Xpert-negative cases exhibited greater detection sensitivity (97.4%) than did smear microscopy (23.4%, P < 0.01). Meanwhile, 74.1% of TB patients initially diagnosed as TB-negative via smear microscopy were identified using Xpert testing of BALF at reduced diagnostic cost/patient (from USD 266.9 to 171.5). Conclusions BALF samples added incremental value to pulmonary TB diagnostic strategies for patients with Xpert-negative sputum. Xpert outperformed smear microscopy for tubercle bacilli detection in both sputum and BALF.