A Survey on the Practice and Interpretation of Various Diagnostic Tests for Tuberculous Pleuritis Among Respiratory Physicians

Tuberculosis (TB) is one of the major global health threats, with an estimated 10.6 million people infected with TB in 2021, with 1.6 million dying from the disease. Apart from pulmonary involvement as the major manifestation of TB, there is an increasing trend of extrapulmonary TB (EPTB) reported in different continents. Among EPTB, TB pleuritis (TBP) was the most prevalent form in several large Chinese retrospective studies.

Diagnosing TBP is challenging due to paucibacillary involvement (TB disease caused by a small number of bacteria) of the pleural space. A diagnosis of definite TBP can be secured if the acid-fast bacilli (AFB), Mycobacterium tuberculosis (MTB) culture of pleural fluid reveals positive results. However, these conventional diagnostic tests for TBP are insufficiently sensitive, and the long turnaround time of culture would also delay the initial clinical management. The diagnosis of definite TBP may also be based on compatible histological findings of the pleural tissue obtained by biopsy procedures (bedside biopsy by Abram's needle, real-time image-guided biopsy by radiologists or experienced respiratory physicians, or pleuroscopy). The availability and waiting time of these procedures vary in different regions. Due to these reasons, a diagnosis of probable TBP may be pursued instead. This diagnostic entity is based on compatible clinical presentations with exudative, lymphocytic pleural effusion and raised pleural fluid biomarkers, commonly adenosine deaminase (ADA), without diagnostic microbiological results and alternative clinical explanation [10]. Other than pleural fluid ADA, several pleural fluid biomarkers have been explored to assist in diagnosing probable TBP. Therefore, a significant proportion of patients suspected to have TBP may have empirical anti-TB treatment initiated in the absence of a confirmatory diagnosis. In addition, these diagnostic clinical challenges are magnified among Asia-Pacific developing countries where contemporary diagnostic tools may be unavailable and hinder local TB control.

There is a lack of regional Asia-Pacific real-world evidence of how TBP is diagnosed and how pleural fluid biomarkers are used. We hypothesise that heterogeneous practice towards new-onset unilateral pleural effusion and understanding different diagnostic tests for diagnosing TBP across different countries depends on the TB burden and availability of advanced pleural services. Therefore, a multinational survey study is designed to understand the real-world practice of managing new-onset unilateral pleural effusion, the availability and utilisation of different diagnostic tests for TBP, and the factors determining the timing of initiating empirical anti-TB treatment for TBP among respiratory physicians in the Asia-Pacific region.