Abstract:

Objective To evaluate the diagnostic value of several tests in Mycobacterium tuberculosis (MTB) detection by the combination of pleural fluid and sputum in tuberculous pleurisy.Methods Of 1955 cases with tuberculous pleurisy admitted in Beijing Chest Hospital from January 2014 to March 2017 were retrospectively analyzed. There were 1232 cases (63.02%) with pulmonary parenchyma and 723 cases (36.98%) without pulmonary parenchyma. According to the positive detection rate of MTB in single and combined detection of sputum and pleural effusion by AFB, modified roche solid culture, BACTEC 960 and Xpert, the effect of pulmonary parenchyma lesion on the positive rate of MTB need to be analyzed.Results Of 1955 cases with tuberculous pleurisy, 535 cases (27.37%) of sputum and pleural effusion were examined by AFB and 353 cases (18.06%) by culture and 294 cases (15.04%) by Xpert. Among them, 188 cases (9.62%) were examined simultaneously by AFB, culture and Xpert. The positive rate of AFB, culture and Xpert (3.18% (17/535), 15.30% (54/353), 19.05% (56/294)) in detecting MTB in pleural effusion was significantly lower than that in sputum combination with pleural effusion (21.87% (117/535), 43.63% (154/353), 47.62% (140/294); χ ² were 85.31, 68.16 and 54.00, respectively. All P values were less than 0.01). In patients with pulmonary parenchyma disease, the positive rate of detection for MTB in pleural effusion by AFB, culture and Xpert alone (3.82% (13/340), 16.30% (37/227) and 23.91% (44/184)) was significantly lower than that in sputum (30.29% (103/340), 51.10% (116/227) and 60.33% (111/184); χ ² were 84.19, 61.53 and 50.04, respectively. All P values were less than 0.01), and also lower than that in sputum combination with pleural effusion (32.06% (109/340), 55.95% (127/227) and 67.93% (125/184); χ ² were 92.06, 77.32 and 71.79 respectively. All P values were less than 0.01). When using culture as gold standard, the sensitivity of AFB, culture and Xpert (48.36% (59/122), 79.38% (77/97), 80.49% (66/82)) in detecting sputum combination with pleural effusion was significantly higher than that in single pleural effusion (8.20% (10/122), 26.80% (26/97), 26.83% (22/82); χ ² were 48.52, 53.84 and 47.47 respectively. All P values were less than 0.01). The specificity of three tests in detecting sputum combination with pleural effusion was lower than that in single pleural effusion. There was no significant difference in AFB (χ ²=3.65,P=0.056), but significant difference in Xpert (χ ²=4.71, P=0.030) and AFB combination with Xpert (χ ²=5.67, P=0.017). Conclusion Due to the positive rate of MTB in sputum and pleural effusion was higher than that in single test, the combined detection of sputum and pleural effusion should be carried out in patients suspected of tuberculous pleurisy in order to improve the diagnostic value.

Key words: Tuberculosis,pleural, Sputum, Pleural effusion, Diagnostic techniques and procedures, Evaluation studies