Clinical characteristics and potential indicators for definite diagnosis of tuberculous pleural effusion

Clinical significance of pleural fluid lactate dehydrogenase/adenosine deaminase ratio in the diagnosis of tuberculous pleural effusion

BACKGROUND

Pleural fluid is one of the common complications of thoracic diseases, and tuberculous pleural effusion (TPE) is the most common cause of pleural effusion in TB-endemic areas and the most common type of exudative pleural effusion in China. In clinical practice, distinguishing TPE from pleural effusion caused by other reasons remains a relatively challenging issue. The objective of present study was to explore the clinical significance of the pleural fluid lactate dehydrogenase/adenosine deaminase ratio (pfLDH/pfADA) in the diagnosis of TPE.

METHODS

The clinical data of 618 patients with pleural effusion were retrospectively collected, and the patients were divided into 3 groups: the TPE group (412 patients), the parapneumonic pleural effusion (PPE) group (106 patients), and the malignant pleural effusion (MPE) group (100 patients). The differences in the ratios of pleural effusion-related and serology-related indicators were compared among the three groups, and receiver operating characteristic curves were drawn to analyze the sensitivity and specificity of the parameter ratios of different indicators for the diagnosis of TPE.

RESULTS

The median serum ADA level was higher in the TPE group (13 U/L) than in the PPE group (10 U/L, P < 0.01) and MPE group (10 U/L, P < 0.001). The median pfADA level in the TPE group was 41 (32, 52) U/L; it was lowest in the MPE group at 9 (7, 12) U/L and highest in the PPE group at 43 (23, 145) U/L. The pfLDH level in the PPE group was 2542 (1109, 6219) U/L, which was significantly higher than that in the TPE group 449 (293, 664) U/L. In the differential diagnosis between TPE and non-TPE, the AUC of pfLDH/pfADA for diagnosing TPE was the highest at 0.946 (0.925, 0.966), with an optimal cutoff value of 23.20, sensitivity of 93.9%, specificity of 87.0%, and Youden index of 0.809. In the differential diagnosis of TPE and PPE, the AUC of pfLDH/pfADA was the highest at 0.964 (0.939, 0.989), with an optimal cutoff value of 24.32, sensitivity of 94.6%, and specificity of 94.4%; this indicated significantly better diagnostic efficacy than that of the single index of pfLDH. In the differential diagnosis between TPE and MPE, the AUC of pfLDH/pfADA was 0.926 (0.896, 0.956), with a sensitivity of 93.4% and specificity of 80.0%; this was not significantly different from the diagnostic efficacy of pfADA.

CONCLUSIONS

Compared with single biomarkers, pfLDH/pfADA has higher diagnostic value for TPE and can identify patients with TPE early, easily, and economically.

Diagnostic value and safety of medical thoracoscopy for pleural effusion of different causes

BACKGROUND

Pleural effusions occur for various reasons, and their diagnosis remains challenging despite the availability of different diagnostic modalities. Medical thoracoscopy (MT) can be used for both diagnostic and therapeutic purposes, especially in patients with undiagnosed pleural effusion.

AIM

To assess the diagnostic efficacy and safety of MT in patients with pleural effusion of different causes.

METHODS

Between January 1, 2012 and April 30, 2021, patients with pleural effusion underwent MT in the Department of Respiratory Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University (Shaanxi, China). According to the discharge diagnosis, patients were divided into malignant pleural effusion (MPE), tuberculous pleural effusion (TBPE), and inflammatory pleural effusion (IPE) groups. General information, and tuberculosis- and effusion-related indices of the three groups were analyzed. The diagnostic yield, diagnostic accuracy, performance under thoracoscopy, and complications of patients were compared among the three groups. Then, the significant predictive factors for diagnosis between the MPE and TBPE groups were analyzed.

RESULTS

Of the 106 patients enrolled in this 10-year study, 67 were male and 39 female, with mean age of 57.1 ± 14.184 years. Among the 74 thoracoscopy-confirmed patients, 41 (38.7%) had MPE, 21 had (19.8%) TBPE, and 32 (30.2%) were undiagnosed. Overall diagnostic yield of MT was 69.8% (MPE: 75.9%, TBPE: 48.8%, and IPE: 75.0%, with diagnostic accuracies of 100%, 87.5%, and 75.0%, respectively). Under thoracoscopy, single or multiple pleural nodules were observed in 81.1% and pleural adhesions in 34.0% with pleural effusions. The most common complication was chest pain (41.5%), followed by chest tightness (11.3%) and fever (10.4%). Multivariate logistic regression analyses showed effusion appearance [odds ratio (OR): 0.001, 95%CI: 0.000-0.204; P = 0.010] and carcinoembryonic antigen (OR: 0.243, 95%CI: 0.081-0.728; P = 0.011) as significant for differentiating MPE and TBPE, with area under the receiver operating characteristic curve of 0.977 (95%CI: 0.953-1.000; P < 0.001).

CONCLUSION

MT is an effective, safe, and minimally invasive procedure with high diagnostic yield for pleural effusion of different causes.

Use of T-SPOT.TB for the diagnosis of unconventional pleural tuberculosis is superior to ADA in high prevalence areas: a prospective analysis of 601 cases

BACKGROUND

Tuberculous pleural effusion (TPE) is the most common extrapulmonary manifestation and may have lasting effect on lung function. However conventional diagnostic tests for TPE register multiple limitations. This study estimates diagnostic efficacy of the interferon gamma release assay (IGRA: T-SPOT.TB) in TPE patients of different characteristics.

METHODS

We performed a prospective, single-centre study including all suspected pleural effusion patients consecutively enrolled from June 2015 to October 2018. Through receiver operating characteristic (ROC) curves, technical cut-offs and the utility of T-SPOT on pleural fluid (PF) were determined and analysed. Logistic regression analysis was performed to obtain the independent risk factors for TPE, and evaluated the performance of the T-SPOT assay stratified by risk factors in comparison to ADA.

RESULTS

A total of 601 individuals were consecutively recruited. The maximum spot-forming cells (SFCs) of early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) in the PF T-SPOT assay had the best diagnostic efficiency in our study, which was equal to ADA (0.885 vs 0.887, P = 0.957) and superior to peripheral blood (PB), with a sensitivity of 83.0% and a specificity of 83.1% (The cut-off value was 466 SFCs/10⁶ mononuclear cells). Among the TPE patients with low ADA (< 40 IU/L), the sensitivity and specificity of PF T-SPOT were still 87.9 and 90.5%, respectively. The utility of ADA was negatively related to increasing age, but the PF T-SPOT test had a steady performance at all ages. Age (< 45 yrs.; odds ratio (OR) = 5.61, 95% confidence interval (CI) 3.59-8.78; P < 0.001), gender (male; OR = 2.68, 95% CI 1.75-2.88; P < 0.001) and body mass index (BMI) (< 22; OR = 1.93, 95% CI 1.30-2.88; P = 0.001) were independently associated with the risk of TB by multivariate logistic regression analysis. Notably, when stratified by risk factor, the sensitivity of PF T-SPOT was superior to the sensitivity for ADA (76.5% vs. 23.5%, P = 0.016) and had noninferior specificity (84.4% vs. 96.9%, P = 0.370).

CONCLUSIONS

In conclusion, the PF T-SPOT assay can effectively discriminate TPE patients whose ADA is lower than 40 IU/L and is superior to ADA in unconventional TPE patients (age ≥ 45 yrs., female or BMI ≥ 22). The PF T-SPOT assay is an excellent choice to supplement ADA to diagnose TPE.