Diagnostic accuracy of T-cell interferon-γ release assays in tuberculous pleurisy: a meta-analysis

Pleural fluid biochemical analysis: the past, present and future

Identifying the cause of pleural effusion is challenging for pulmonologists. Imaging, biopsy, microbiology and biochemical analyses are routinely used for diagnosing pleural effusion. Among these diagnostic tools, biochemical analyses are promising because they have the advantages of low cost, minimal invasiveness, observer independence and short turn-around time. Here, we reviewed the past, present and future of pleural fluid biochemical analysis. We reviewed the history of Light’s criteria and its modifications and the current status of biomarkers for heart failure, malignant pleural effusion, tuberculosis pleural effusion and parapneumonic pleural effusion. In addition, we anticipate the future of pleural fluid biochemical analysis, including the utility of machine learning, molecular diagnosis and high-throughput technologies. Clinical Chemistry and Laboratory Medicine (CCLM) should address the topic of pleural fluid biochemical analysis in the future to promote specific knowledge in the laboratory professional community.

Pleural Fluid Soluble Interleukin-2 Receptor as a Biomarker for the Diagnosis of Tuberculosis Pleural Effusion: A Systematic Review and Meta-Analysis

Background

Several studies have assessed the diagnostic accuracy of pleural fluid soluble interleukin-2 receptor (sIL-2R) for tuberculous pleural effusion (TPE) but with varied results. Therefore, we conducted this systematic review and meta-analysis to evaluate the accuracy of sIL-2R for TPE.

Methods

PubMed, Ovid, and Web of Science databases were searched from inception to 23 March 2021 to identify eligible studies concerning the diagnostic accuracy of fluid sIL-2R for TPE. The sensitivity and specificity of sIL-2R for TPE were pooled with a bivariate model. We estimated the global diagnostic accuracy of PE sIL-2R with a summary receiver operating characteristic (sROC) curve. The revised Quality Assessment for Diagnostic Accuracy Studies tool (QUADAS-2) was used to assess the quality of eligible studies.

Results

A total of nine studies with 270 TPEs and 586 non-TPEs were included in the final analysis. The pooled sensitivity and specificity were 0.81 (95% CI: 0.76–0.86) and 0.92 (95% CI: 0.77–0.98), respectively. The area under the sROC curve (AUC) was 0.82 (95% CI: 0.79–0.86). No significant publication bias was observed.

Conclusions

Pleural fluid sIL-2R is a useful diagnostic marker for TPE. However, the diagnostic accuracies of already available biomarkers such as pleural fluid adenosine deaminase, interferon-γ, and interleukin-27 appear to be superior relative to sIL-2R. Therefore, it might not be preferable to use sIL-2R for diagnosing TPE.

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.

The value of single or combined use of pleural fluid interferon gamma release assay in the diagnosis of tuberculous pleurisy

OBJECTIVE

Tuberculous pleurisy (TP) is a common disease of extrapulmonary tuberculosis, but its diagnosis is challenging. Recently, studies have found that the pleural fluid interferon gamma release assay (PF-IGRA) has important diagnostic value in TP, but the sample size of these studies was small, and the conclusions were inconsistent. Therefore, this study evaluated the diagnostic value of PF-IGRA in TP through a meta-analysis.

METHODS

We conducted a literature search in multiple databases to identify studies and calculated the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), summary receiver operating characteristic (SROC) curve and area under the curve (AUC).

RESULTS

All 26 publications, including 30 case-control studies, were eventually included in the meta-analysis. The results showed that the pooled sensitivity, specificity, PLR, NLR, DOR and AUC with their 95% confidence intervals were 0.90 (0.88-0.91), 0.87 (0.85-0.89), 7.64 (4.46-13.07), 0.13 (0.09-0.19), 65.45 (32.13-133.33) and 0.9508, respectively. The subgroup analysis suggested that the sensitivity, specificity and AUC of PF-IGRA for TP in areas with a high tuberculosis burden were significantly higher than those in areas with a low tuberculosis burden. The sensitivity and AUC of the enzyme-linked immunosorbent assay method were higher than those of the enzyme-linked immunosorbent assay method for IGRA, but the specificity was similar. More importantly, PF-IGRA combined with adenosine deaminase (ADA) could increase the diagnostic value of TP.

CONCLUSIONS

The current meta-analysis indicated that PF-IGRA has high diagnostic value in diagnosing TP, especially in areas with a high TB burden. We recommended that the combination of PF-IGRA and ADA is the best way to diagnose TP.

Adenosine deaminase negative pleural tuberculosis: a case report

Background

A pleural fluid adenosine deaminase (ADA) has been used globally to assist in the diagnosis of a tuberculous pleural effusion (TPE) with a notable negative predictive value.

Case presentation

We report a case of a patient with a negative pleural fluid ADA who was found to have culture-positive and biopsy-proven Mycobacterium tuberculosis.

Conclusions

This case shows the importance of pursuing gold standard diagnostic studies when clinical suspicion remains high despite negative preliminary testing. We further describe gaps in research to improve pleural fluid biomarkers for TPE.

Acute myeloid leukemia with leukemic pleural effusion and high levels of pleural adenosine deaminase: A case report and review of literature

Pleural effusions are rarely observed in association with acute myeloid leukemia (AML), and their true incidence remains unknown. Given the low diagnostic yield from cytopathologic analysis of malignant pleural effusions and the fact that patients with leukemia are often thrombocytopenic and unable to tolerate invasive procedures, the incidence of leukemic effusions may be underestimated. Here, we report a rare case of pleural effusion in a patient with newly diagnosed AML. Initial analysis revealed an exudative, lymphocyte-predominant effusion. High levels of adenosine deaminase (ADA) were detected in pleural fluid, consistent with a diagnosis of tuberculosis. However, the analysis of pleural cytology revealed leukemic cells, permitting the diagnosis of leukemic effusion to be made. The patient underwent induction chemotherapy and pleural effusion resolved without recurrence. This case emphasizes the diagnostic dilemma presented by high levels of ADA in a leukemic pleural effusion, as this association has not been previously considered in the literature.

The diagnostic utility of pleural markers for tuberculosis pleural effusion

Tuberculosis pleural effusion (TPE) is common in clinical practice, and its diagnosis remains a challenge for clinicians. Ziehl-Neelsen staining, PE Mycobacterium tuberculosis culture, and biopsy are the gold standards for TPE diagnosis; however, they are time-consuming, invasive, observer-dependent, and insensitive. PE markers represent a rapid, low-cost, and non-invasive objective diagnostic tool for TPE. In the past decades, several PE biomarkers have been developed, and their diagnostic accuracy has been evaluated in many studies. Here, we reviewed the literature to summarize the diagnostic accuracy of these biomarkers, especially using the evidence from systematic review and meta-analysis. The current research strongly suggests that adenosine deaminase (ADA), interferon-gamma (IFN-γ), and interleukin 27 (IL-27) have extremely higher diagnostic accuracy for TPE, while the diagnostic accuracy of interferon gamma release assays (IGRAs), tumor necrosis factor-α (TNF-α), and interferon-γ-induced protein 10 kDa (IP-10) is moderate. Although some evidence supports C-X-C motif chemokine ligand 9 (CXCL9), CXCL11, CXCL12, sFas ligand, angiotensin-converting enzyme (ACE), calpain-1, spectrin breakdown products (SBDP), matrix metalloproteinase-1 (MMP-1), soluble CD26 (sCD26), soluble interleukin 2 receptor (sIL-2R) as useful diagnostic markers for TPE, more support is needed to validate their diagnostic accuracy. Finally, nucleic acid amplification tests (NAATs) have extremely high diagnostic specificity, but their sensitivity is low. Taken together, ADA is the preferred marker for TPE because its low cost and suitability for standardization.

The diagnostic effect of sequential detection of ADA screening and T-SPOT assay in pleural effusion patients

Purpose: To evaluate the diagnostic effect of sequential detection of Adenosine deaminase (ADA) screening and T-SPOT assay on tuberculosis (TB) pleurisy in pleural effusion patients. Materials and methods: 248 pleural effusion patients (172 TB and 76 non-TB) were retrospectively analyzed in the study. The concentrations of ADA and lactate dehydrogenase (LDH) were measured in pleural fluids and serum samples of the patients. T-SPOTT assays were performed in pleural fluids. The relationship between ADA, T-SPOT and the occurrence of TB pleurisy was evaluated using logistic regression analysis. Results: The level of pleural ADA and positive rate of T-SPOT were all higher in TB pleurisy group than non-TB pleurisy group (p < .001). The positive rate of T-SPOT detection reached 98.83% in the TB pleurisy group while only 40.7% in non-TB pleurisy group (p < .001). Additionally, 8 patients (4.65%) in the TB pleurisy group showed the level of pleurisy ADA exceeded 40 IU/L while only one patient (1.31%) in the non-TB pleurisy group. Conclusion: The sequential detection of ADA screening and T-SPOT assay was found to be an accurate and rapid method for identifying TB pleurisy from pleural effusion, which would promote effective treatment.

Advances in pleural effusion diagnostics

Introduction: Pleural effusion is a common clinical problem. Yet, in a significant proportion of patients (~20%), the cause of pleural effusion remains unknown. Understanding the diagnostic value of pleural fluid tests is crucial for the development of accurate diagnostic models.Areas covered: This paper provides an overview of latest advances in the diagnosis of pleural effusion based on the best evidence available.Expert opinion: For pleural fluid tests to have a good diagnostic value, it is necessary that data obtained from clinical history, physical examination, and radiological studies are correctly interpreted. Thoracentesis and pleural biopsy should always be performed under image guidance to improve its diagnostic sensitivity and prevent complications. Nucleic acid amplification tests, pleural tissue cultures, and collection of pleural fluid in blood culture bottles improve the diagnostic yield of pleural fluid cultures. Although undiagnosed pleural effusions generally have a favorable prognosis, follow-up is recommended to prevent the development of a malignant pleural effusion.

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.

An outbreak of tuberculosis due to Mycobacterium bovis infection in a pack of English Foxhounds (2016-2017)

Mycobacterium bovis can cause tuberculosis (TB) in social mammals including lions, cattle and man, but canine infections are considered rare. In 2016/17 we investigated a M. bovis TB outbreak in a pack of approximately 180 Foxhounds within the bovine TB Edge Area of England. We employed a combination of immunological tests including an interferon gamma release assay (IGRA) and a serological assay (DPP VetTB, Chembio). Test‐positive hounds were euthanased and subjected to post‐mortem examination (PME). Overall 164 hounds were tested; 97 (59%) responded positively to at least one test. Eighty‐five (52%) dogs responded to M. bovis antigens by IGRA while only 21 (12.9%) had detectable serological responses. At PME three hounds (3.1%) had visible lesions (VL) due to M. bovis infection, later confirmed by culture. Samples from 24 non‐VL hounds were cultured and M. bovis infection was confirmed in a further three hounds (11%). This study is the first investigation and report of an outbreak of M. bovis TB in a canine species. We establish that, in principle, diagnostic tests used for identifying infected individuals of other species can effectively be used in the dog. Further work is urgently needed to establish the sensitivity and specificity of the testing approach used in this study for future clinical application.

Pleurisy Caused by Mycobacterium abscessus in a Young Patient with Dermatomyositis: A Case Report and Brief Review of the Literature

M. abscessus is a rapidly growing mycobacteria (RGM) and is the most common cause of pulmonary RGM infection. M. abscessus pleurisy is extremely rare. We herein report the case of a young patient with M. abscessus pleurisy without any lung lesions. A laboratory analysis of the pleural effusion revealed lymphocyte predominance and increased adenosine deaminase, similar to the findings observed in tuberculous pleurisy. The patient was initially treated for tuberculous pleurisy, which resulted in the partial improvement of the patient's symptoms and pleural effusion. M. abscessus pleurisy should be considered, especially in immunocompromised individuals, even in the absence of pulmonary involvement.

Diagnostic Accuracy of Interleukin-27 between Tuberculous Pleural Effusion and Malignant Pleural Effusion: A Meta-Analysis

BACKGROUND

The concentration assay of pleural effusion interleukin-27 (IL-27) has raised concern for diagnosing tuberculous pleurisy. Compared with malignant pleural effusion (MPE), the concentration of IL-27 in tuberculous pleural effusion (TPE) increased significantly. Accurate differentiating diagnosis is essential for choosing treatment for pleural effusion.

OBJECTIVE

The present meta-analysis is aimed at determining the accuracy of IL-27 in the differential diagnosis between TPE and MPE.

MATERIAL AND METHOD

After having retrieved the published studies, we combined the sensibility (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of IL-27 in the diagnosis of TPE compared to MPE using a fixed-effect model. The summary receiver operating characteristic curve was applied to estimate the overall test performance.

RESULTS

In total, 550 patients (285 patients with TPE and 265 patients with MPE), included in 7 case-control studies, were enrolled. The summary assessments for IL-27 in the diagnosis between TPE and MPE were: SEN 0.93 (95% CI 0.90-0.96), SPE 0.97 (95% CI 0.94-0.98), PLR 25.88 (95% CI 13.84-48.39), NLR 0.07 (95% CI 0.05-0.11), and DOR 333.26 (95% CI 146.10-760.19), respectively. The maximal joint SEN and SPE was 0.95; the area under the curve was 0.99.

CONCLUSION

IL-27 determination is a relatively accurate test for the diagnosis of TPE, which has very high SEN and SPE for discriminating TPE from MPE. The results of IL-27 assays should be interpreted in parallel with clinical findings and the results of conventional tests.

Pleural fluid tests to diagnose tuberculous pleuritis

PURPOSE OF REVIEW

This article summarizes current data regarding the accuracy of pleural fluid tests assisting the diagnosis of tuberculous pleuritis (TBP).

RECENT FINDINGS

No pleural fluid test reliably rules-in TBP in settings with low TBP prevalence. Interferon-γ) alone or in combination with adenosine deaminase (ADA) is more reliable than ADA for this purpose in nonlow prevalences. ADA can reliably rule-out TBP in prevalences of less than 40% although in higher prevalences the product of interleukin-27 and ADA is the most accurate rule-out test.

SUMMARY

The definite diagnosis of TBP requires the isolation of Mycobacterium tuberculosis from pleural fluid or biopsies. Because of the low sensitivity of pleural fluid cultures and the invasiveness of pleural biopsy techniques, the concept of a pleural fluid test that accurately establishes or excludes TBP diagnosis has been proposed. Numerous pleural fluid tests have been evaluated for this purpose with ADA being the most widely accepted one. During the last years, it has been demonstrated that the ability of ADA to rule-in or rule-out TBP is affected by the prevalence of TBP in the setting where the test is used. The complementary use of interferon-γ or interleukin-27 increases the ability of ADA to rule-in or rule-out the disease, respectively.

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.

Rapid Detection of Cell-Free Mycobacterium tuberculosis DNA in Tuberculous Pleural Effusion

Tuberculous pleurisy is one of the most common types of extrapulmonary tuberculosis, but its diagnosis remains difficult. In this study, we report for the first time on the detection of cell-free Mycobacterium tuberculosis DNA in pleural effusion and an evaluation of a newly developed molecular assay for the detection of cell-free Mycobacterium tuberculosis DNA. A total of 78 patients with pleural effusion, 60 patients with tuberculous pleurisy, and 18 patients with alternative diseases were included in this study. Mycobacterial culture, the Xpert MTB/RIF assay, the adenosine deaminase assay, the T-SPOT.TB assay, and the cell-free Mycobacterium tuberculosis DNA assay were performed on all the pleural effusion samples. The cell-free Mycobacterium tuberculosis DNA assay and adenosine deaminase assay showed significantly higher sensitivities of 75.0% and 68.3%, respectively, than mycobacterial culture and the Xpert MTB/RIF assay, which had sensitivities of 26.7% and 20.0%, respectively (P < 0.01). All four of these tests showed good specificities: 88.9% for the adenosine deaminase assay and 100% for the remaining three assays. The T-SPOT.TB assay with pleural effusion showed the highest sensitivity of 95.0% but the lowest specificity of 38.9%. The cell-free Mycobacterium tuberculosis DNA assay detected as few as 1.25 copies of IS6110 per ml of pleural effusion and showed good accordance of the results between repeated tests (r = 0.978, P = 2.84 × 10^-10). These data suggest that the cell-free Mycobacterium tuberculosis DNA assay is a rapid and accurate molecular test which provides direct evidence of Mycobacterium tuberculosis etiology.

The top-cited systematic reviews/meta-analyses in tuberculosis research: A PRISMA-compliant systematic literature review and bibliometric analysis

BACKGROUND

The top-cited systematic reviews/meta-analyses in tuberculosis research have not been identified. The objective of this study was to identify the 100 top-cited systematic reviews/meta-analyses in tuberculosis research, and to understand factors resulting in highly cited works, and establish trends in systematic reviews/meta-analyses in tuberculosis research.

METHODS

The Web of Science Core Collection was searched for systematic reviews/meta-analyses on tuberculosis up to January 31, 2016. Articles were ranked by citation count and screened by 2 authors. The following information was collected and analyzed from each included study: citation of Web of Science Core Collection, author, country, year, journal, institution, page number, and reference number.

RESULTS

The 100 top-cited studies were cited from 54 to 662 times and were published between 1997 and 2014. Ten authors have more than 1 study as the first author and 10 authors have more than 1 study as corresponding author. The country with the most top-cited studies was USA (n = 26). The institutions with the largest number of the studies were McGill University in Canada (n = 18). The studies were published in 32 journals, whereas 12 were published in PloS Medicine, followed by Lancet Infectious Diseases (n = 11).

CONCLUSIONS

Developed countries and high-impact journals may publish more top-cited systematic review/meta-analysis in tuberculosis research.

Tuberculous pleural effusion

Although it is curable, tuberculosis remains one of the most frequent causes of pleural effusions on a global scale, especially in developing countries. Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis. TPE usually presents as an acute illness with fever, cough and pleuritic chest pain. The pleural fluid is an exudate that usually has predominantly lymphocytes. The gold standard for the diagnosis of TPE remains the detection of Mycobacterium tuberculosis in pleural fluid, or pleural biopsy specimens, either by microscopy and/or culture, or the histological demonstration of caseating granulomas in the pleura along with acid fast bacilli, Although adenosine deaminase and interferon-γ in pleural fluid have been documented to be useful tests for the diagnosis of TPE. It can be accepted that in areas with high tuberculosis prevalence, the easiest way to establish the diagnosis of TPE in a patient with a lymphocytic pleural effusion is to generally demonstrate a adenosine deaminase level above 40 U/L. The recommended treatment for TPE is a regimen with isoniazid, rifampin, and pyrazinamide for two months followed by four months of two drugs, isoniazid and rifampin.

A combination of the QuantiFERON-TB Gold In-Tube assay and the detection of adenosine deaminase improves the diagnosis of tuberculous pleural effusion

The differential diagnosis of tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) remains difficult despite the availability of numerous diagnostic tools. The current study aimed to evaluate the performance of the whole blood QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and conventional laboratory biomarkers in differential diagnosis of TPE and MPE in high tuberculosis prevalence areas. A total of 117 patients with pleural effusions were recruited, including 91 with TPE and 26 with MPE. All of the patients were tested with QFT-GIT, and the conventional biomarkers in both blood and pleural effusion were detected. The level of antigen-stimulated QFT-GIT in the whole blood of TPE patients was significantly higher than that of MPE (2.89 vs 0.33 IU/mL, P<0.0001). The sensitivity and specificity of QFT-GIT for the diagnosis of TPE were 93.0% and 60.0%, respectively. Among the biomarkers in blood and pleural effusion, pleural adenosine deaminase (ADA) was the most prominent biomarker, with a cutoff value of 15.35 IU/L. The sensitivity and specificity for the diagnosis of TPE were 93.4% and 96.2%, respectively. The diagnostic classification tree from the combination of these two biomarkers was 97.8% sensitive and 92.3% specific. Ultimately, the combination of whole blood QFT-GIT with pleural ADA improved both the specificity and positive predictive value to 100%. Thus, QFT-GIT is not superior to pleural ADA in the differential diagnosis of TPE and MPE. Combined whole blood QFT-GIT and pleural ADA detection can improve the diagnosis of TPE.

Accuracy of the Bronchoalveolar Lavage Enzyme-Linked Immunospot Assay for the Diagnosis of Pulmonary Tuberculosis: A Meta-analysis

Assessing of local immune response may improve the accuracy of pulmonary tuberculosis (PTB) diagnosis. Many studies have investigated diagnosing PTB based on enzyme-linked immunospot (ELISPOT) assay of bronchoalveolar lavage (BAL) fluid, but the results have been inconclusive. We meta-analyzed the available evidences on overall diagnostic performance of ELISPOT assay of BAL fluid for diagnosing PTB.A systematic literature search was performed using PubMed, Embase, Wangfang, Weipu, and CNKI. Data were pooled on sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR). Overall test performance was summarized using summary receiver operating characteristic curves and the area under the curve (AUC). Deeks test was used to test for potential publication bias.Seven publications with 814 subjects met our inclusion criteria and were included in this meta-analysis. The following pooled estimates for diagnostic parameters were obtained: sensitivity, 0.90 (95% CI: 0.85-0.94); specificity, 0.80 (95% CI: 0.77-0.84); PLR, 5.08 (95% CI: 2.70-9.57); NLR, 0.13 (95% CI: 0.06-0.28); DOR, 49.12 (95% CI: 12.97-186.00); and AUC, 0.96. No publication bias was identified.The available evidence suggests that ELISPOT assay of BAL fluid is a useful rapid diagnostic test for PTB. The results of this assay should be interpreted in parallel with clinical findings and the results of conventional tests.

Guidelines for the use of interferon-γ release assays in the diagnosis of tuberculosis infection

INTRODUCTION

Interferon-gamma release assays are widely used for the diagnosis of tuberculosis infection in low-prevalence countries. However, there is no consensus on their application. The objective of this study was to develop guidelines for the use of interferon-gamma release assays in specific clinical scenarios in Spain.

METHODS

A panel of experts comprising specialists in infectious diseases, respiratory diseases, microbiology, pediatrics and preventive medicine, together with a methodologist, formulated the clinical questions and outcomes of interest. They conducted a systematic literature search, summarized the evidence and rated its quality, and prepared the recommendations following the GRADE (Grading of Recommendations of Assessment Development and Evaluations) methodology.

RESULTS

The panel prepared recommendations on the use of interferon-gamma release assays for the diagnosis of tuberculosis infection in the contact-tracing study (both adults and children), health care workers, immunosuppressed patients (patients infected with human immunodeficiency virus, patients with chronic immunomediated inflammatory diseases due to start biological therapy and patients requiring organ transplant) and for the diagnosis of active tuberculosis. Most recommendations were weak, mainly due to the lack of good quality evidence to balance the clinical benefits and disadvantages of the interferon-gamma release assays as compared with the tuberculin skin test.

CONCLUSION

This document provides evidence-based guidance on the use of interferon-gamma release assays for the diagnosis of tuberculosis infection in patients at risk of tuberculosis or with suspicion of active disease. The guidelines will be applicable in specialist and primary care and in public health settings.

Diagnostic accuracy of pleural fluid tumor necrosis factor-α in tuberculous pleurisy: A meta-analysis

BACKGROUND

Pleurisy is a common extra pulmonary complication of tuberculosis, but current methods for diagnosing it are fairly crude. Here we product a meta-analysis for the available evidence on the ability of tumor necrosis factor-α (TNF-α) in pleural fluid to serve as a diagnostic marker of tuberculous pleurisy (TP).

MATERIALS AND METHODS

We searched the PubMed, EMBASE, and Google Scholar databases systematically for studies measuring sensitivity, specificity and other measures of diagnostic accuracy of pleural fluid TNF-α in the diagnosis of TP were meta-analyzed by Stata, version 12 and meta-disc.

RESULTS

A total of six publications reporting seven case-control studies were identified. Pooled results indicated that pleural fluid TNF-α showed a diagnostic sensitivity of 0.89 (95% confidence interval [95% CI] 0.83-0.93; range, 0.42-1.0) and a diagnostic specificity of 0.82 (95% CI: 0.78-0.86; range, 0.58-0.98). The pooled positive likelihood ratio was 4.78 (95% CI: 3.32-6.89); the negative likelihood ratio, 0.16 (95% CI: 0.1-0.27); the diagnostic odds ratio, 32.43 (95% CI: 14.48-72.6); and the area under the curve was 0.8556 (standard error of mean 0.0559).

CONCLUSION

Pleural fluid TNF-α levels shows relatively high sensitivity but insufficient specificity for diagnosing TP. Pleural fluid TNF-α measurement may be useful in combination with clinical manifestations and conventional tests such as microbiological examination or pleural biopsy.

Body Fluid Interferon-γ Release Assay for Diagnosis of Extrapulmonary Tuberculosis in Adults: A Systematic Review and Meta-Analysis

The diagnosis of extrapulmonary tuberculosis (EPTB) is difficult. In recent years, T-cell interferon-γ release assays (IGRAs) are widely used in diagnosing tuberculosis. The aim of this meta-analysis is to evaluate the diagnostic accuracy of body fluid IGRAs in diagnosing EPTB. The PubMed, EMBASE, Web of Science, and Cochrane bibliographies were searched for English language articles. 22 studies met the inclusion criteria. The pooled sensitivity and specificity of body fluid IGRAs for diagnosing EPTB were 0.87 [95% confidence interval (CI): 0.83–0.92] and 0.85 (95% CI: 0.79–0.90), respectively. For the fluid T-SPOT.TB, the pooled sensitivity and specificity were 0.92 (95% CI: 0.88–0.95) and 0.85 (95% CI: 0.78–0.91), respectively. The diagnostic odds ratio (DOR) of the fluid T-SPOT.TB was 46.99 (95% CI: 13.69–161.28) for tuberculosis pleurisy, 26.46 (95% CI: 11.38–61.56) for tuberculosis peritonitis, and 97.86 (95% CI: 25.31–378.45) for tuberculosis meningitis. The application of T-SPOT. TB in the diagnosis of EPTB performed better in the body fluid than in the blood. The diagnostic values of the fluid T-SPOT.TB varied for different fluid categories. However, the utility of T-SPOT.TB was limited due to its suboptimal accuracy and higher cost compared with conventional tests.

Accuracy of the interferon-gamma release assay for the diagnosis of tuberculous pleurisy: an updated meta-analysis

Background and Objectives. The best method for diagnosing tuberculous pleurisy (TP) remains controversial. Since a growing number of publications focus on the interferon-gamma release assay (IGRA), we meta-analyzed the available evidence on the overall diagnostic performance of IGRA applied to pleural fluid and peripheral blood. Materials and Methods. PubMed and Embase were searched for relevant English papers up to October 31, 2014. Statistical analyses were performed using Stata and Meta-DiSc. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), positive predictive value (PPV), negative predictive value (NPV) and diagnostic odds ratio (DOR) were count. Summary receiver operating characteristic curves and area under the curve (AUC) were used to summarize the overall diagnostic performance. Results. Fifteen publications met our inclusion criteria and were included in the meta analysis. The following pooled estimates for diagnostic parameters of pleural IGRA were obtained: sensitivity, 0.82 (95% CI [0.79-0.85]); specificity, 0.87 (95% CI [0.84-0.90]); PLR, 4.94 (95% CI [2.60-9.39]); NLR, 0.22 (95% CI [0.13-0.38]); PPV, 0.91 (95% CI [0.85-0.96]); NPV, 0.79 (95% CI [0.71-0.85]); DOR, 28.37 (95% CI [10.53-76.40]); and AUC, 0.91. The corresponding estimates for blood IGRA were as follows: sensitivity, 0.80 (95% CI [0.76-0.83]); specificity, 0.70 (95% CI [0.65-0.75]); PLR, 2.48 (95% CI [1.95-3.17]); NLR, 0.30 (95% CI [0.24-0.37]); PPV, 0.79 (95% CI [0.60-0.87]); NPV, 0.75 (95% CI [0.62-0.83]); DOR, 9.96 (95% CI [6.02-16.48]); and AUC, 0.89. Conclusions. This meta analysis suggested that pleural IGRA has potential for serving as a complementary method for diagnosing TP; however, its cost, high turn around time, and sub-optimal performance make it unsuitable as a stand-alone diagnostic tool. Better tests for the diagnosis of TP are required.

Interferon Gamma Release Assays for Diagnosis of Pleural Tuberculosis: a Systematic Review and Meta-Analysis

The role of interferon gamma release assays (IGRAs), although established for identifying latent tuberculosis, is still evolving in the diagnosis of active extrapulmonary tuberculosis. We systematically evaluated the diagnostic performance of blood- and pleural fluid-based IGRAs in tuberculous pleural effusion (TPE). We searched the PubMed and Embase databases for studies evaluating the use of commercially available IGRAs on blood and/or pleural fluid samples for diagnosing TPE. The quality of the studies included was assessed through the QUADAS-2 tool. The pooled estimates of sensitivity and specificity with 95% confidence intervals (95% CI) were generated using a bivariate random-effects model and examined using forest plots and hierarchical summary receiver operating characteristic (HSROC) curves. Indeterminate IGRA results were included for sensitivity calculations. Heterogeneity was explored through subgroup analysis and meta-regression based on prespecified covariates. We identified 19 studies assessing the T.SPOT.TB and/or QuantiFERON assays. There were 20 and 14 evaluations, respectively, of whole-blood and pleural fluid assays, involving 1,085 and 727 subjects, respectively. There was only one good-quality study, and five studies used nonstandard assay thresholds. The pooled sensitivity and specificity for the blood assays were 0.77 (95% CI, 0.71 to 0.83) and 0.71 (95% CI, 0.65 to 0.76), respectively. The pooled sensitivity and specificity for the pleural fluid assays were 0.72 (95% CI, 0.55 to 0.84) and 0.78 (95% CI, 0.65 to 0.87), respectively. There was considerable heterogeneity; however, multivariate meta-regression did not identify any covariate with significant influence. There was no publication bias for blood assays. We conclude that commercial IGRAs, performed either on whole-blood or pleural fluid samples, have poor diagnostic accuracy in patients suspected to have TPE.

Diagnosis and treatment of extrapulmonary tuberculosis

Extrapulmonary tuberculosis (EPTB) constitutes about 20% of all cases of tuberculosis (TB) in Korea. Diagnosing EPTB remains challenging because clinical samples obtained from relatively inaccessible sites may be paucibacillary, thus decreasing the sensitivity of diagnostic tests. Whenever practical, every effort should be made to obtain appropriate specimens for both mycobacteriologic and histopathologic examinations. The measurement of biochemical markers in TB-affected serosal fluids (adenosine deaminase or gamma interferon) and molecular biology techniques such as polymerase chain reaction may be useful adjuncts in the diagnosis of EPTB. Although the disease usually responds to standard anti-TB drug therapy, the ideal regimen and duration of treatment have not yet been established. A paradoxical response frequently occurs during anti-TB therapy. It should be distinguished from other causes of clinical deterioration. Surgery is required mainly to obtain valid diagnostic specimens and to manage complications. Because smear microscopy or culture is not available to monitor patients with EPTB, clinical monitoring is the usual way to assess the response to treatment.

Tuberculous Pleural Effusion

When a patient presents with new pleural effusion, the diagnosis of tuberculous (TB) pleuritis should be considered. The patient is at risk for developing pulmonary or extrapulmonary TB if the diagnosis is not made. Between 3% and 25% of patients with TB will have TB pleuritis. The incidence of TB pleuritis is higher in patients who are human immunodeficiency virus (HIV)-positive. Pleural fluid is an exudate that usually has a predominance of lymphocytes. The easiest way to diagnose TB pleuritis in a patient with lymphocytic pleural effusion is to demonstrate a pleural fluid adenosine deaminase level above 40 IU/L. The treatment for TB pleuritis is the same as that for pulmonary TB. Tuberculous empyema is a rare occurrence, and the treatment is difficult.

[Contribution of pleural fluid analysis to the diagnosis of pleural effusion]

Analysis of pleural fluid can have, on its own, a high diagnostic value. In addition to thoracocentesis, a diagnostic hypothesis based on medical history, physical examination, blood analysis and imaging tests, the diagnostic effectiveness will significantly increase in order to establish a definite or high probable diagnosis in a substantial number of patients. Differentiating transudates from exudates by the classical Light's criteria helps knowing the pathogenic mechanism resulting in pleural effusion, and it is also useful for differential diagnosis purposes. An increased N-terminal pro-brain natriuretic peptide, both in the fluid and in blood, in a due clinical context, is highly suggestive of heart failure. The presence of an increased inflammatory marker, such as C-reactive protein, together with the presence of over 50% of neutrophils is highly suggestive of parapneumonic pleural effusion. If, in these cases, the pH is<7.20, then the likelihood of complicated pleural effusion is high. There remains to be demonstrated the usefulness of other markers to differentiate complicated from uncomplicated effusions. An adenosine deaminase > 45 U/L and>50% lymphocytes is suggestive of tuberculosis. If a malignant effusion is suspected but the cytological result is negative, increased concentrations of some markers in the pleural fluid can yield high specificity values. Increased levels of mesothelin and fibruline-3 are suggestive of mesothelioma. Immunohistochemical studies can be useful to differentiate reactive mesothelial cells, mesothelioma and metastatic adenocarcinoma. An inadequate use of the information provided by the analysis of pleural fluid would results in a high rate of undiagnosed effusions, which is unacceptable in current clinical practice.

Tuberculous pleurisy: an update

Tuberculous pleurisy is the most common form of extrapulmonary tuberculosis in Korea. Tuberculous pleurisy presents a diagnostic and therapeutic problem due to the limitations of traditional diagnostic tools. There have been many clinical research works during the past decade. Recent studies have provided new insight into the tuberculous pleurisy, which have a large impact on clinical practice. This review is a general overview of tuberculous pleurisy with a focus on recent findings on the diagnosis and management.

Tuberculous pleural effusion

Tuberculous pleural effusion (TBPE) is the most common form of extrapulmonary tuberculosis (TB) in Spain, and is one of the most frequent causes of pleural effusion. Although the incidence has steadily declined (4.8 cases/100,000population in 2009), the percentage of TBPE remains steady with respect to the total number of TB cases (14.3%-19.3%). Almost two thirds are men, more than 60% are aged between 15-44years, and it is more common in patients with human immunodeficiency virus. The pathogenesis is usually a delayed hypersensitivity reaction. Symptoms vary depending on the population (more acute in young people and more prolonged in the elderly). The effusion is almost invariably a unilateral exudate (according to Light's criteria), more often on the right side, and the tuberculin test is negative in one third of cases. There are limitations in making a definitive diagnosis, so various pleural fluid biomarkers have been used for this. The combination of adenosine deaminase and lymphocyte percentage may be useful in this respect. Treatment is the same as for any TB. The addition of corticosteroids is not advisable, and chest drainage could help to improve symptoms more rapidly in large effusions.

Effectiveness of interferon-gamma release assays for differentiating intestinal tuberculosis from Crohn’s disease: A meta-analysis

AIM: To investigate the clinical usefulness of interferon-gamma release assays (IGRAs) in the differential diagnosis of intestinal tuberculosis (ITB) from Crohn’s disease (CD) by meta-analysis.

METHODS: A systematic search of English language studies was performed. We searched the following databases: Medline, Embase, Web of Science and the Cochrane Library. The Standards for Reporting Diagnostic Accuracy initiative and Quality Assessment for Studies of Diagnostic Accuracy tool were used to assess the methodological quality of the studies. Sensitivity, specificity, and other measures of the accuracy of IGRAs in the differential diagnosis of ITB from CD were pooled and analyzed using random-effects models. Receiver operating characteristic curves were applied to summarize overall test performance. Two reviewers independently judged study eligibility while screening the citations.

RESULTS: Five studies met the inclusion criteria. The average inter-rater agreement between the two reviewers for items in the quality checklist was 0.95. Analysis of IGRAs for the differential diagnosis of ITB from CD produced summary estimates as follows: sensitivity, 0.74 (95%CI: 0.68-0.80); specificity, 0.87 (95%CI: 0.82-0.90); positive likelihood ratio, 5.98 (95%CI: 3.79-9.43); negative likelihood ratio, 0.28 (95%CI: 0.18-0.43); and diagnostic odds ratio, 26.21 (95%CI: 14.15-48.57). The area under the curve was 0.92. The evaluation of publication bias was not significant (P = 0.235).

CONCLUSION: Although IGRAs are not sensitive enough, they provide good specificity for the accurate diagnosis of ITB, which may be helpful in the differential diagnosis of ITB from CD.

Pleural fluid biomarkers: beyond the Light criteria

Although distinguishing transudates from exudates through the Light criteria is still considered a pragmatic first step in the diagnostic work-up of pleural effusions, the measurement of various pleural fluid biomarkers may aid in the identification of common and specific entities, such as heart failure (natriuretic peptides), tuberculosis (adenosine deaminase), malignancy (mesothelin, fibulin-3, immunocytochemical stains), or bacterial pleural infections (C-reactive protein). The use of these biomarkers is currently encouraged as a routine diagnostic procedure.

Atypical tuberculous pleural effusions

Typically, a tuberculous pleural effusion is submassive, unilateral, and has the appearance of a clear straw coloured fluid with a cellular content predominantly consisting of lymphocytes. Atypical characteristics of tuberculous pleural effusion do, however, need to be recognised to mitigate the risk of delayed diagnosis, the latter sometimes resulting in potentially avoidable deaths, and also to reduce the risk that untreated patients might transmit the disease.