The Role of Post-Bronchoscopy Sputum Examination in Screening for Active Tuberculosis

Area of Science:

• Pulmonary Medicine
• Infectious Diseases
• Diagnostic Microbiology

Background:

• Early tuberculosis (TB) diagnosis is crucial for global control efforts.
• Current TB screening in Qatar involves chest radiology and initial sputum tests.
• Bronchoscopy with bronchoalveolar lavage (BAL) is used for TB diagnosis in select cases.

Purpose of the Study:

• To evaluate the diagnostic yield of post-bronchoscopy sputum (PBS) testing.
• To determine if PBS enhances tuberculosis detection when added to BAL.
• To assess the impact of PBS on diagnostic accuracy metrics.

Main Methods:

• Prospective enrollment of 495 individuals undergoing bronchoscopy for TB evaluation.
• Collection of two PBS samples for acid-fast bacilli (AFB) smears and mycobacterial cultures.
• Comparison of diagnostic yield with and without the addition of PBS to BAL results.

Main Results:

• PBS testing confirmed tuberculosis in an additional 13 patients (3.9% yield).
• Inclusion of PBS improved diagnostic sensitivity from 77.9% to 81.9%.
• Negative predictive value increased from 69.2% to 73.2%, and negative likelihood ratio decreased to 0.18.

Conclusions:

• Routine post-bronchoscopy sputum examination can enhance the diagnostic yield for tuberculosis.
• PBS testing offers a valuable adjunct to bronchoalveolar lavage in TB work-up.
• This approach can improve microbiological confirmation where resources permit.