Characteristics of pleural effusion due to paradoxical response in patients with pulmonary tuberculosis

Background: Patients with pulmonary tuberculosis may present with deterioration of pleural effusion during antituberculosis therapy, referred to as a paradoxical response (PR), with some patients requiring additional intervention. However, PR may be confused with other differential diagnoses, and the predictive factors for recommending additional therapies are unknown. Therefore, this study aimed to reveal useful information for the diagnosis and intervention of PR.Methods: Data from human immunodeficiency virus-negative patients with tuberculous pleurisy (n = 210), including 184 patients with pre-existing pleural effusion and 26 patients with PR at Fukujuji Hospital, were retrospectively collected from January 2012 to December 2022 and compared. Furthermore, patients with PR were divided into the intervention group (n = 9) and the no intervention group (n = 17) and were compared.Results: Patients in the PR group had lower pleural lactate dehydrogenase (LDH) (median 177 IU/L vs. 383 IU/L, p < 0.001) and higher pleural glucose (median 122 mg/dL vs. 93 mg/dL, p < 0.001) levels than those in the preexisting pleural effusion group. Other pleural fluid data were not significantly different. Patients in the intervention group had a shorter duration from the initiation of anti-tuberculosis therapy to the development of PR than patients in the no intervention group (median 19.0 days [interquartile range (IQR): 18.0-22.0] vs. median 37.0 days [IQR: 28.0-58.0], p = 0.012).Conclusion: This study demonstrates that, apart from lower pleural LDH and elevated pleural glucose levels, PR presents with similar features to preexisting pleural effusion and that patients who develop PR faster tend to require intervention.