Pleural fluid tests to diagnose tuberculous pleuritis

Application of Adenosine Deaminase and γ-Interferon Release Assay in Pleural Fluid for the Diagnosis of Tuberculous Pleural Effusion in Patients Over 40 Years Old

Background

In patients with tuberculous pleural effusion (TPE) of various ages, the diagnostic accuracy of pleural biomarkers varies, and there are insufficient studies specifically in different age groups. Therefore, we investigated the adenosine deaminase cut-off value and its combination with the gamma interferon release assay for the diagnosis of TPE among patients aged ≥40 years.

Methods

A retrospective analysis of 198 patients who underwent medical thoracoscopy and were admitted to the hospital between 2015 and 2020 with exudative pleural effusion and either fever, night sweats, fatigue, cough, or other clinical manifestations was performed. The medical thoracoscopy, ADA, and T-SPOT results were analysed in the pleural fluid. The patients were divided into groups based on age: 18-39, 40-59, and 60-87.

Results

The best cut-off values of ADA were 29.5, 31.5 and 19.5 U/L, respectively, for the aged 18-39, aged 40-87 and aged 60-87 groups. The accuracy of 31.5 U/L was higher than 40 U/L for aged ≥40 years (86 vs 83%). The ADA diagnostic accuracy was higher than that of people under 40 years (83 vs 77%) when cut-off value of ADA was 40 U/L, but the IGRA accuracy was lower than that of people under 40 (87 vs 91%). The sensitivity of ADA or IGRA detection in patients over 40 years was 99%, and the specificity was 78%. The ADA specificity combined with IGRA for TPE was the highest (100%) in the ≥40 age group, and the sensitivity was 69%.

Conclusion

Our study revealed the best cut-off values of ADA for TBE in different age groups. Combining ADA and IGRA in pleural fluid improves the detection rate of TPE in patients over 40 years of age with exudative pleural effusion. ADA combined with IGRA increases specificity, and ADA or IGRA increases sensitivity substantially.

Diagnosis and Treatment of Pleural Effusion. Recommendations of the Spanish Society of Pulmonology and Thoracic Surgery. Update 2022

Pleural effusion (PE) is a common yet complex disease that requires specialized, multidisciplinary management. Recent advances, novel diagnostic techniques, and innovative patient-centered therapeutic proposals have prompted an update of the current guidelines. This document provides recommendations and protocols based on a critical review of the literature on the epidemiology, etiology, diagnosis, prognosis, and new therapeutic options in PE, and addresses some cost-effectiveness issues related to the main types of PE.

Interleukin 32 as a Potential Marker for Diagnosis of Tuberculous Pleural Effusion

Accurate differential diagnosis is the key to choosing the correct treatment for pleural effusion. The present study aimed to assess whether interleukin 32 (IL-32) could be a new biomarker of tuberculous pleural effusion (TPE) and to explore the biological role of IL-32 in TPE. IL-32 levels were evaluated in the pleural effusions of 131 patients with undetermined pleural effusion from Wuhan and Beijing cohorts using an enzyme-linked immunosorbent assay method. Macrophages from TPE patients were transfected with IL-32-specific small interfering RNA (siRNA), and adenosine deaminase (ADA) expression was determined by real-time PCR and colorimetric methods. With a cutoff value of 247.9 ng/mL, the area under the curve of the receiver operating characteristic (ROC) curve for IL-32 was 0.933 for TPE, and the sensitivity and specificity were 88.4% and 93.4%, respectively. A multivariate logistic regression model with relatively good diagnostic performance was established. IL-32-specific siRNA downregulated ADA expression in macrophages, and IL-32γ treatment significantly induced ADA expression. Our results indicate that IL-32 in pleural effusion may be a novel biomarker for identifying patients with TPE. In addition, our multivariate model is acceptable to rule in or rule out TPE across diverse prevalence settings. Furthermore, IL-32 may modulate ADA expression in the tuberculosis microenvironment. (This study has been registered at ChiCTR under registration number ChiCTR2100051112 [https://www.chictr.org.cn/index.aspx].) IMPORTANCE Tuberculous pleural effusion (TPE) is a common form of extrapulmonary tuberculosis, with manifestations ranging from benign effusion with spontaneous absorption to effusion with pleural thickening, empyema, and even fibrosis, which can lead to a lasting impairment of lung function. Therefore, it is of great significance to find a rapid method to establish early diagnosis and apply antituberculosis therapy in the early stage. This study indicates that interleukin 32 (IL-32) in pleural effusion is a new high-potency marker to distinguish TPE from pleural effusions with other etiologies. A multivariate model combining age, adenosine deaminase (ADA), lactic dehydrogenase, and IL-32 may reliably rule in TPE in intermediate- or high-prevalence areas. Additionally, we observed that IL-32 might regulate ADA expression in macrophages in the tuberculosis microenvironment. Therefore, this study provides new insights into the role of IL-32 in the tuberculosis microenvironment.

Use of Platelet Parameters in the Differential Diagnosis of Lung Adenocarcinoma-Associated Malignant Pleural Effusion and Tuberculous Pleural Effusion

Background

Both malignant pleural effusion (MPE) and tuberculous pleural effusion (TPE) are common etiologies of pleural effusion; the present study was conducted to establish the diagnostic value of platelet parameters in the differential diagnosis of MPE and TPE.

Methods

This retrospective study enrolled patients with lung adenocarcinoma-associated MPE and TPE. Platelet parameter data, including platelet count (PLT), mean platelet volume (MPV), plateletcrit (PCT), platelet distribution width (PDW), and platelet-larger cell ratio (P-LCR), were collected. Principal component analysis and multiple logistic regression modelling were carried out to assess the diagnostic value of these platelet parameters.

Results

The MPE group and the TPE group enrolled 270 and 433 patients, respectively. Demographic characteristics of patients were more female and higher age in the MPE group. MPV, PDW, and P-LCR were significantly higher in MPE patients, while PLT and PCT were significantly higher in TPE patients. Principal component analysis generated two principal components (PCs) based on above platelet parameters. After adjusting for confounding factors including gender and age, multiple logistic regression showed positive association between PC1 and MPE.

Conclusion

Platelet parameters were potential biomarkers in distinguishing lung adenocarcinoma-associated MPE from TPE. A patient with lower PLT and PCT and higher MPV, PDW, and P-LCR was more likely to be diagnosed as the former. Principal component analysis and multiple logistic regression performed well in improving multicollinearity, adjusting confounding factors, and identifying important risk factors for MPE.

Pleural Tuberculosis

Pleural tuberculosis (TB) is common and often follows a benign course but may result in serious long-term morbidity. Diagnosis is challenging because of the paucibacillary nature of the condition. Advances in Mycobacterium culture media and PCR-based techniques have increased the yield from mycobacteriologic tests. Surrogate biomarkers perform well in diagnostic accuracy studies but must be interpreted in the context of the pretest probability in the individual patient. Confirming the diagnosis often requires biopsy, which may be acquired through thoracoscopy or image-guided closed pleural biopsy. Treatment is standard anti-TB therapy, with optional drainage and intrapleural fibrinolytics or surgery in complicated cases.

Diagnostic accuracy of adenosine deaminase for pleural tuberculosis in a low prevalence setting: A machine learning approach within a 7-year prospective multi-center study

OBJECTIVE

To analyze the performance of adenosine deaminase in pleural fluid combined with other parameters routinely measured in clinical practice and assisted by machine learning algorithms for the diagnosis of pleural tuberculosis in a low prevalence setting, and secondly, to identify effusions that are non-tuberculous and most likely malignant.

PATIENTS AND METHODS

We prospectively analyzed 230 consecutive patients diagnosed with lymphocytic exudative pleural effusion from March 2013 to June 2020. Diagnosis according to the composite reference standard was achieved in all cases. Pre-test probability of pleural tuberculosis was 3.8% throughout the study period. Parameters included were: levels of adenosine deaminase, pH, glucose, proteins, and lactate dehydrogenase, red and white cell counts and lymphocyte percentage in pleural fluid, as well as age. We tested six different machine learning-based classifiers to categorize the patients. Two different classifications were performed: a) tuberculous/non-tuberculous and b) tuberculous/malignant/other.

RESULTS

Out of a total of 230 patients with pleural effusion included in the study, 124 were diagnosed with malignant effusion and 44 with pleural tuberculosis, while 62 were given other diagnoses. In the tuberculous/non-tuberculous classification, and taking into account the validation predictions, the support vector machine yielded the best result: an AUC of 0.98, accuracy of 97%, sensitivity of 91%, and specificity of 98%, whilst in the tuberculous/malignant/other classification, this type of classifier yielded an overall accuracy of 80%. With this three-class classifier, the same sensitivity and specificity was achieved in the tuberculous/other classification, but it also allowed the correct classification of 90% of malignant cases.

CONCLUSION

The level of adenosine deaminase in pleural fluid together with cell count, other routine biochemical parameters and age, combined with a machine-learning approach, is suitable for the diagnosis of pleural tuberculosis in a low prevalence scenario. Secondly, non-tuberculous effusions that are suspected to be malignant may also be identified with adequate accuracy.

Comparative accuracy of pleural fluid unstimulated interferon-gamma and adenosine deaminase for diagnosing pleural tuberculosis: A systematic review and meta-analysis

Objective

We compared diagnostic accuracy of pleural fluid adenosine deaminase (ADA) and interferon-gamma (IFN-γ) in diagnosing tuberculous pleural effusion (TPE) through systematic review and comparative meta-analysis.

Methods

We queried PubMed and Embase databases to identify studies providing paired data for sensitivity and specificity of both pleural fluid ADA and IFN-γ for diagnosing TPE. We used hierarchical summary receiver operating characteristic (HSROC) plots and HSROC meta-regression to model individual and comparative diagnostic performance of the two tests.

Results

We retrieved 376 citations and included 45 datasets from 44 publications (4974 patients) in our review. Summary estimates for sensitivity and specificity for ADA were 0.88 (95% CI 0.85–0.91) and 0.91 (95% CI 0.89–0.92), while for IFN-γ they were 0.91 (95% CI 0.89–0.94) and 0.96 (95% CI 0.94–0.97), respectively. HSROC plots showed consistently greater diagnostic accuracy for IFN-γ over ADA across the entire range of observations. HSROC meta-regression using test-type as covariate yielded a relative diagnostic odds ratio of 2.22 (95% CI 1.68–2.94) in favour of IFN-γ, along with better summary sensitivity and specificity figures. No prespecified subgroup variable significantly influenced the summary diagnostic accuracy estimates.

Conclusion

Pleural fluid IFN-γ estimation has better diagnostic accuracy than ADA estimation for diagnosis of TPE.

GC-MS metabolomics identifies novel biomarkers to distinguish tuberculosis pleural effusion from malignant pleural effusion

Background

Tuberculous pleural effusions (TBPEs) and malignant pleural effusions (MPEs) are two of the most common and severe forms of exudative effusions. Clinical differentiation is challenging; however, metabolomics is a collection of powerful tools currently being used to screen for disease‐specific biomarkers.

Methods

17 TBPE and 17 MPE patients were enrolled according to the inclusion criteria. The normalization gas chromatography‐mass spectrometry (GC‐MS) data were imported into the SIMCA‐P + 14.1 software for multivariate analysis. The principal component analysis (PCA) and orthogonal partial least‐squares discriminant analysis (OPLS‐DA) were used to analyze the data, and the top 50 metabolites of variable importance projection (VIP) were obtained. Metabolites were qualitatively analyzed using the National Institute of Standards and Technology (NIST) databases. Pathway analysis was performed by MetaboAnalyst 4.0. The detection of biochemical indexes such as urea and free fatty acids in these pleural effusions was also verified, and significant differences were found between these two groups.

Results

1319 metabolites were screened by non‐targeted metabonomics of GC‐MS. 9 small molecules (urea, L‐5‐oxoproline, L‐valine, DL‐ornithine, glycine, L‐cystine, citric acid, stearic acid, and oleamide) were found to be significantly different (p < 0.05 for all). In OPLS‐DA, 9 variables were considered significant for biological interpretation (VIP≥1). However, after the ROC curve was performed, it was found that the metabolites with better diagnostic value were stearic acid, L‐cystine, citric acid, free fatty acid, and creatinine (AUC > 0.8), with good sensitivity and specificity.

Conclusion

Stearic acid, L‐cystine, and citric acid may be potential biomarkers, which can be used to distinguish between the TBPE and the MPE.

Diagnostics in Pleural Disease

Pleural disease diagnostics represent a sprawling topic that has enjoyed a renaissance in recent years from humble beginnings. Whilst pleural patients are heterogeneous as a population and in the aetiology of the disease with which they present, we provide an overview of the typical diagnostic approach. Pleural fluid analysis is the cornerstone of the diagnostic pathway; however, it has many shortcomings. Strong cases have been made for more invasive upfront investigations, including image-guided biopsies or local anaesthetic thoracoscopy, in selected populations. Imaging can guide the diagnostic process as well as act as a vehicle to facilitate therapies, and this is never truer than with the recent advances in thoracic ultrasound.

Influence of age on the diagnostic accuracy of soluble biomarkers for tuberculous pleural effusion: a post hoc analysis

BACKGROUND

Accurately diagnosing pleural effusion is a frequent and significant problem in clinical practice. Combining pleural biomarkers with patients' age may be a valuable method for diagnosing TPE. We sought to evaluate the influence of age on diagnostic values of pleural adenosine deaminase (ADA), interferon-gamma (IFN-γ), and interleukin 27 (IL-27) for tuberculous pleural effusion (TPE).

METHODS

Two hundred seventy-four consecutive adult patients with pleural effusion were selected from Beijing and Wuhan between January 1, 2014 and June 30, 2015, and their pleural fluid concentrations of ADA, IFN-γ, and IL-27 were tested. Biomarker performance was analyzed by standard receiver operating characteristic (ROC) curves according to different ages.

RESULTS

Data from the Beijing cohort showed that ADA, IFN-γ, and IL-27 could all accurately diagnose TPE in young patients (≤ 40 years of age). With a cutoff of 21.4 U/L, the area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ADA for diagnosing TPE were 1.000 (95% confidence interval: 0.884-1.000), 100.0, 100.0%, 100.0, and 100.0, respectively. In older patients (> 40 years of age), IL-27 and IFN-γ were excellent biomarkers for discriminating TPE versus non-TPE cases. With a cutoff of 591.4 ng/L, the AUC, sensitivity, specificity, PPV, and NPV of IL-27 for diagnosing TPE were 0.976 (95% confidence interval: 0.932-0.995), 96.3, 99.0%, 96.3, and 99.0, respectively. Similar diagnostic accuracy among the three pleural biomarkers was validated in the Wuhan cohort.

CONCLUSIONS

Among young patients, ADA is reliable for diagnosing TPE. Conversely, in older patients, IL-27 and IFN-γ are excellent biomarkers to differentiate TPE versus non-TPE cases.

Cell-free Mycobacterium tuberculosis DNA test in pleural effusion for tuberculous pleurisy: a diagnostic accuracy study

OBJECTIVES

Tuberculous pleurisy (TP) diagnosis remains difficult, with the sensitivity of Xpert MTB/RIF (Xpert) and mycobacterial culture (culture) only about 30-50%. We aimed to assess the diagnostic performance of a cell-free Mycobacterium tuberculosis DNA test (cf-TB) in pleural effusion for TP.

METHODS

Adults (≥18 years) with suspected TP presenting with pleural effusion were consecutively recruited, and pleural effusion specimens were prospectively collected in Beijing Chest Hospital, Beijing, China. After centrifuging pleural effusion, sediments were used for culture, Xpert and T-SPOT.TB assay, whereas supernatants were used for cf-TB and adenosine deaminase assay. The diagnostic performance was assessed against a composite reference standard.

RESULTS

From June 2015 to December 2018, we prospectively evaluated 286 adults with suspected TP. One hundred twenty-two participants were classified as definite TP based on the prespecified composite reference standard. The cf-TB produced a sensitivity of 79.5% (97/122, 95% confidence interval (CI) 72.4- 86.7) for definite TP, which was superior to Xpert (38.5% (29.9-47.2); 47/122; p < 0.001) and culture (27.1% (19.2-34.9); 33/122; p < 0.001). With pleural effusion Xpert and/or culture as the reference standard, cf-TB showed 96.6% (57/59, 95% CI 92.0-100.0) sensitivity, which was also significantly higher than Xpert (79.7%, 95% CI 69.4-89.9; 47/59; p 0.004) and culture (55.9%, 95% CI: 43.3-68.6; 33/59; p < 0.001).

CONCLUSIONS

The cf-TB clearly showed improved sensitivity compared with Xpert and culture. We recommend cf-TB as the first-line test for TP diagnosis.

Comparison of pleural effusion features and biomarkers between talaromycosis and tuberculosis in non-human immunodeficiency virus-infected patients

Background

Due to the similar clinical, lung imaging, and pathological characteristics, talaromycosis is most commonly misdiagnosed as tuberculosis. This study aimed to identify the characteristics of talaromycosis pleural effusion (TMPE) and to distinguish TMPE from tuberculosis pleural effusion (TPE).

Methods

We enrolled 19 cases each of TMPE and TPE from Guangxi, China. Patients’ clinical records, pleural effusion tests, biomarker test results, and receiver operating characteristic curves were analyzed.

Results

In total, 39.8% (65/163) of patients exhibited serous effusion, of whom 61 were non-human immunodeficiency virus (HIV)-infected patients; 68.85% of the non-HIV-infected patients (42/61) had TMPE. Thoracentesis was performed only in 19 patients, all of whom were misdiagnosed with tuberculosis and received long-term anti-tuberculosis treatment. In four of these patients, interleukin (IL)-23, IL-27, and interferon-gamma (IFN-γ) measurements were not performed since pleural effusion samples could not be collected because the effusion had been drained prior to the study. In the remaining 15 patients, pleural effusion samples were collected. Talaromyces marneffei was isolated from the pleural effusion and pleural nodules. Most TMPEs were characterized by yellowish fluid, with marked elevation of protein content and nucleated cell counts. However, neutrophils were predominantly found in TMPEs, and lymphocytes were predominantly found in TPEs (both p < 0.05). Adenosine deaminase (ADA) and IFN-γ levels in TMPEs were significantly lower than those in TPEs (all p < 0.05) and provided similar accuracies for distinguishing TMPEs from TPEs. IL-23 concentration in TMPEs was significantly higher than that in TPEs (p < 0.05), and it provided similar accuracy for diagnosing TMPEs. IL-27 concentrations in TMPEs were significantly lower than those in TPEs (all p < 0.05) but was not useful for distinguishing TMPE from TPE.

Conclusions

Talaromycosis can infringe on the pleural cavity via the translocation of T. marneffei into the pleural space. Nonetheless, this phenomenon is still commonly neglected by clinicians. TMPE is a yellowish fluid with exudative PEs and predominant neutrophils. Higher neutrophil counts and IL-23 may suggest talaromycosis. Higher lymphocyte counts, ADA activity, and IFN-γ concentration may suggest tuberculosis.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4376-6) contains supplementary material, which is available to authorized users.

Tuberculous pleural effusion: diagnosis & management

Background: Tuberculosis (TB) is the world's leading cause of death from infectious disease. The World Health Organization (WHO) recognized 6.3 million new TB cases in 2017, 16% corresponding to extrapulmonary forms; pleural tuberculosis (PT) is the most common extrapulmonary form in adults. PT diagnosis is often challenging because the scarcity of bacilli in pleural fluid (PF), sometimes requiring invasive procedures to obtain pleural tissue for histological, microbiological or molecular examination. In regions of medium and high disease prevalence, adenosine deaminase (ADA), interferon gamma (IFN-γ) and interleukin 27 (IL-27) dosages are useful to establish presumptive diagnosis in patients with compatible clinical/radiological picture who present with lymphocytic pleural effusion. PT treatment is similar to the pulmonary TB treatment regimen recommended by WHO. Area covered: In this update, we present a PT review, including epidemiology, pathogenesis, clinical features, diagnosis, and therapy. Expert opinion: There is no PF test alone accurate for PT diagnosis, despite the evolution in clinical laboratory. ADA, IFN-γ and IL-27 are valuable laboratory biomarkers; however, IFN-γ and IL-27 are quite expensive. Molecular tests present low sensitivity in PF, being useful for diagnostic confirmation. Multidrug therapy remains the PT treatment choice. Advancing research in immunotherapy may bring benefits to PT patients.

Drug resistance in patients with tuberculous pleural effusions

PURPOSE OF REVIEW

To summarize data regarding categories, detection methods, prevalence and patterns of drug resistance among patients with tuberculous pleural effusion (TPE) and to comment on the management of suspected drug-resistant TPE.

RECENT FINDINGS

Pleural and pulmonary tuberculosis (TB) present similar patterns of drug resistance. Approximately 10% and 6-10% of pleural Mycobacterium tuberculosis isolates are resistant to at least one first-line anti-TB drug or at least isoniazid, respectively. The prevalence of multidrug-resistant-pleural and extensively drug-resistant-pleural TB is 1-3% and 0-1%, respectively.

SUMMARY

Although guidelines suggest the empirical standard anti-TB regimen (i.e. 2 months of isoniazid, rifampicin, pyrazinamide and ethambutol followed by 4 months of isoniazid and rifampicin) for TPE treatment, the data regarding drug resistance among TPE patients are limited. The few studies examining the issue report a notable drug resistance. In suspected drug-resistant TPE, every effort is warranted to isolate M. tuberculosis to perform drug susceptibility testing and provide guided therapy. For this purpose, the use of cultures or molecular methods with pleural biopsies is superior to their use in pleural fluid. If still M. tuberculosis cannot be detected, prolonged administration of ethambutol with isoniazid and rifampicin during the continuation phase of treatment might be considered.

A case report of ocular tuberculosis in a patient with membranous nephropathy

RATIONALE

Membranous nephropathy (MN), a chronic kidney disease (CKD), due to hypoproteinemia, malnutrition, anemia, long-term intake of immunosuppressive agents, changes in cellular immune state, and decrease in antimicrobial peptides, is a high risk for Mycobacterium tuberculosis (MTB) infection, which can cause tuberculosis (TB). TB manifests by various clinical symptoms. Ocular symptoms is a rare presentation of TB. Here, we describe a case of ocular tuberculosis in a patient with MN.

PATIENT CONCERNS

A 63-year-old man with membranous nephropathy (MN) history presented with ocular symptoms.

DIAGNOSES

According to the pathological manifestations of ocular tissue biopsy and a positive polymerase chain reaction (PCR) on samples from sputum and bronchoalveolar lavage fluid (BALF), we elicited a diagnosis of disseminated tuberculosis.

INTERVENTION

The patient received antituberculous therapy and immunosuppressive therapy.

OUTCOMES

The clinical manifestations significantly improved.

LESSONS

Clinicians should be aware of the possibility of TB in cases of immunocompromised patients and perform an appropriate diagnostic work-up for TB.

Impact of age on the diagnostic yield of four different biomarkers of tuberculous pleural effusion

The diagnostic value of pleural fluid biomarkers in tuberculous pleurisy (TP) is firmly established. However, it is less clear whether patients' age affects the diagnostic accuracy of TP biomarkers. The aim of the study was to assess the impact of age, on the predictive value of ADA, IFN-γ, IP-10 and Fas ligand in patients with pleural effusion. The study included 222 patients, median age 64.5 (54-77) years, 58.6% men, with pleural effusion: TPE (60 patients; 27.0%), malignant PE (90 patients; 40.5%), parapneumonic effusion/pleural empyema (35 patients; 15.8%), pleural transudate (30 patients, 13.5%) and other causes of PE (7 patients; 3.2%). The odds ratio for the diagnosis of TPE significantly decreased with increasing age (OR = 0.62/10 years) and significantly increased with increasing level of all evaluated pleural fluid biomarkers. Age affected the diagnostic accuracy of ADA with a trend towards reduction in OR for TPE in older patients (P = 0.077, 95% CI 0.59-1.03). Younger age and high pleural fluid ADA level are associated with very high probability of TP. This probability significantly decreases not only with decreasing pleural fluid ADA, but also with increasing age. Patient's age does not affect the diagnostic yield of pleural fluid IFN-γ, IP-10 and sFas.

Diagnostic accuracy of interleukin-22 and adenosine deaminase for tuberculous pleural effusions

OBJECTIVE

Reliable markers for accurately diagnosing tuberculous pleural effusions (TPE) are needed. This study sought to investigate the diagnostic potential of pleural interleukin-22 (IL-22) and compare it with the performance of adenosine deaminase (ADA).

METHOD

This prospective study involved 49 patients with TPE and 60 patients with pleural effusion of other causes. Pleural levels of IL-22 and ADA were determined, respectively, using ELISA or an enzymatic method. A receiver operating characteristic curve was constructed and the area under the curve (AUC) was calculated to summarize the diagnostic accuracy of single markers or marker combinations.

RESULTS

Levels of IL-22 in pleural effusion were significantly higher in TPE patients than in other patients (322.36 ± 406.65 vs. 83.13 ± 22.15 pg/ml, P < 0.05). With a cut-off value of 97.82 pg/ml, the diagnostic sensitivity of IL-22 for TPE was 71.42%, specificity was 81.67%, and the area under the curve (AUC) was 0.83. ADA levels were also increased in TPE, and its AUC for diagnosing TPE was 0.90. The combination of IL-22 and ADA enhanced diagnostic accuracy, offering sensitivity of 83.67%, specificity of 91.67%, and an AUC of 0.93.

CONCLUSION

IL-22 may be useful for diagnosing TPE, and combining it with ADA may further enhance diagnostic accuracy. Our results justify more rigorous studies with larger samples to confirm the diagnostic potential of IL-22 for TPE.

Pleural tuberculosis: a key differential diagnosis for pleural thickening, even without obvious risk factors for tuberculosis in a low incidence setting

We report the case of a 64-year-old woman, presenting with pleuritic chest pain and weight loss. She had a previous history of breast malignancy and no clear risk factors for tuberculosis (TB). Initial investigations showed a right-sided pleural effusion and pleural thickening suggestive of malignancy, which would have been in keeping with the clinical presentation. Initial pleural biopsy showed features suggestive of possible TB infection, though no growth on cultures. A repeat biopsy was negative on initial microscopy, but was culture positive for Mycobacterium tuberculosis, also identifying isoniazid resistance. This case highlights that TB remains an important differential even in the absence of classical risk factors, and illustrates the diagnostic challenges it poses. It also highlights the value of culture positivity in identification of drug resistance and facilitation of appropriate treatment.

Diagnostic accuracy of interleukin 27 for tuberculous pleural effusion: two prospective studies and one meta-analysis

BACKGROUND

Accurate differentiating diagnosis is essential for choosing treatment for exudative pleural effusions.

OBJECTIVE

To establish the diagnostic accuracy of interleukin 27 for tuberculous pleural effusion (TPE).

METHODS

First, the concentrations of pleural interleukin 27, interferon-gamma and adenosine deaminase were compared between 51 patients with TPE and 103 with non-TPEs (Beijing cohort), and their diagnostic values were evaluated. These were further verified in another independent population (Wuhan cohort, n=120). In the second part of the study, we performed a meta-analysis.

RESULTS

With a cut-off value of 591.4 ng/L in the Beijing cohort, the area under the curve, sensitivity, specificity, positive predictive value and negative predictive value of interleukin 27 to diagnose TPE were 0.983 (95% CI 0.947 to 0.997), 96.1% (86.5% to 99.5%), 99.0% (94.7% to 100%), 98.0 (89.4 to 99.9) and 98.1 (93.3 to 99.8), respectively. Excellent diagnostic accuracy of interleukin 27 was also found in the Wuhan cohort and was further confirmed in the meta-analysis. The diagnostic performance of interleukin 27 was comparable to that of interferon-gamma and was more accurate than that of adenosine deaminase. Since the post-test probability of a negative result was always <0.1%, a negative test was considered to exclude TPE in all tuberculosis prevalence settings.

CONCLUSIONS

Interleukin 27 can be used to diagnose TPE in a high prevalence setting, and a negative result can also be reliably used to rule out TPE in all prevalence settings.

Advances in the diagnosis of tuberculous pleuritis

Pleural tuberculosis (TB) remains difficult to diagnose. In about two-thirds of the cases the diagnosis is reliant upon clinical suspicion along with consistent fluid biochemistries (i.e., lymphocytic predominant exudates) and exclusion of other potential causes for the effusion. Microbiological methods for a confirmatory diagnosis of pleural TB, which include acid-fast smears (Ziehl-Nelseen), cultures on solid media (Lowenstein-Jensen) and polymerase chain reaction tests from either pleural fluid or sputum samples, remain suboptimal since they are positive in only a minority of patients. Liquid media, however, significantly increase sensitivity while shortening culture positivity as compared with solid cultures. A number of pleural fluid biomarkers such as adenosine deaminase (ADA), interferon-Ƴ, interferon-Ƴ-induced protein of 10 KDa (IP-10) and interleukin-27 (IL-27), have shown promise for the rapid diagnosis of TB, but only ADA combines the accuracy and simplicity required to be considered a mainstay investigative tool for clinical decisions, particularly in areas with medium to high TB prevalence. In countries where ADA is not available, pleural biopsies to evaluate for caseating granulomas are a standard diagnostic approach. They are now frequently performed under ultrasound guidance to optimize yield and patient safety.