Performance of adenosine deaminase in detecting paediatric pleural tuberculosis: a systematic review and meta-analysis

Validation of a diagnostic flowchart for tuberculous pleurisy in pleural fluid with high levels of adenosine deaminase

INTRODUCTION

Adenosine deaminase (ADA) in pleural fluid is a useful marker for diagnosing tuberculous pleurisy. However, recent studies have reported a lower specificity of pleural fluid ADA levels. We previously developed a diagnostic flowchart for patients with pleural fluid ADA ≥40 U/L, incorporating variables such as pleural fluid lactate dehydrogenase <825 U/L, predominant pleural fluid neutrophils or cell degeneration, and a pleural fluid ADA/total protein ratio <14. This flowchart was effective in distinguishing between tuberculous pleurisy and other diseases. Here, we conducted a validation analysis of this flowchart.

MATERIALS AND METHODS

We retrospectively collected data from 458 patients with pleural fluid ADA concentrations ≥40 U/L across eight institutions from January 2019 to December 2023. The diagnostic accuracy rate, sensitivity, and specificity of the diagnostic flowchart were analysed and compared to those in the original study.

RESULTS

Eighty-seven patients were diagnosed with tuberculous pleurisy, and 371 patients were diagnosed with other diseases. The diagnostic accuracy, sensitivity, and specificity for diagnosing tuberculous pleurisy were 77.7%, 86.2%, and 75.7%, respectively. Compared with that in the original study, the rate of tuberculous pleurisy was lower (19.0% vs. 44.5%, p < 0.001), but the diagnostic accuracy rates were not significantly different (p = 0.253). On the basis of the findings from this validation study, we have revised the flowchart to enhance its utility.

CONCLUSION

The diagnostic flowchart exhibited high diagnostic accuracy in this validation study, comparable to that in the original study. This validation confirms the effectiveness of the flowchart, even in settings with a low incidence of tuberculosis.

Pleural fluid biomarkers: a narrative review

Background and Objective

Pleural fluid is a source from which various biomarkers can be obtained and measured to facilitate the management and prognostication of various conditions. This narrative review aims to summarise a few selected applications of pleural fluid biomarker analysis based on the latest literature.

Methods

A literature search for articles published in English regarding human subjects from the period January 2000 to December 2023 was performed through PubMed. Publications considered by the authors to be relevant were included in this review, with additional references added based on the authors' judgement. This review considered both prospective and retrospective cohort studies analysing the clinical value of a range of pleural fluid biomarkers.

Key Content and Findings

The biomarkers selected in this narrative review have either established clinical applicability or promising initial results which require further research. Pleural fluid adenosine deaminase, mesothelin and N-terminal pro-B-type natriuretic peptide can optimize the diagnosis of tuberculous pleuritis, malignant mesothelioma and heart failure-related pleural effusion respectively. The detection rate for epidermal growth factor receptor mutations for lung cancer is higher in the pleural fluid than in the pleural tissue or plasma. Suitable targeted therapy in patients with detectable mutations can offer survival benefits. The pleural fluid neutrophil-lymphocyte ratio, soluble urokinase plasminogen activator receptor and plasminogen activator inhibitor 1 carry prognostic implications and can potentially guide subsequent treatment decisions. These biomarkers used individually, or in conjunction with other clinical parameters, should only be utilised in pre-defined, appropriate clinical conditions to maximize their clinical value.

Conclusions

A great variety of different biomarkers are available for analysis in pleural fluid. Further research and development are necessary to widen the spectrum and enhance the clinical utility of pleural fluid biomarkers. Comparison with the diagnostic utilities of serum biomarkers and other investigation parameters, such as radiological findings, could be considered when evaluating the performance of pleural fluid biomarkers.

Diagnostic flowchart for tuberculous pleurisy, pleural infection, and malignant pleural effusion

BACKGROUND

Several markers for the diagnosis of pleural effusion have been reported; however, a comprehensive evaluation using those markers has not been performed. Therefore, this study aimed to develop a diagnostic flowchart for tuberculous pleurisy, pleural infection, malignant pleural effusion, and other diseases by using these markers.

METHODS

We retrospectively collected data from 174 patients with tuberculous pleurisy, 215 patients with pleural infection other than tuberculous pleurisy, 360 patients with malignant pleural effusion, and 209 patients with other diseases at Fukujuji Hospital from January 2012 to October 2022. The diagnostic flowchart for four diseases was developed by using several previously reported markers.

RESULTS

The flowchart was developed by including seven markers: pleural ADA ≥40 IU/L, pleural fluid LDH <825 IU/L, pleural fluid ADA/TP < 14, neutrophil predominance or cell degeneration, peripheral blood WBC ≥9200/μL or serum CRP ≥12 mg/dL, pleural amylase ≥75 U/L, and the presence of pneumothorax according to the algorithm of a decision tree. The accuracy ratio of the flowchart was 71.7 % for the diagnosis of the four diseases, with 79.3 % sensitivity and 75.4 % positive predictive value (PPV) for tuberculosis pleurisy, 75.8 % sensitivity and 83.2 % PPV for pleural infection, 88.6 % sensitivity and 68.8 % PPV for malignant pleural effusion, and 33.0 % sensitivity and 60.0 % PPV for other diseases in the flowchart. The misdiagnosis ratios were 4.6 % for tuberculosis pleurisy, 6.8 % for pleural infection, and 8.3 % for malignant pleural effusion.

CONCLUSION

This study developed a useful diagnostic flowchart for tuberculous pleurisy, pleural infection, malignant pleural effusion, and other diseases.

[Extrapulmonary tuberculosis]

Extrapulmonary tuberculosis (TB) presents unique diagnostic and therapeutic challenges. The site of involvement can vary widely, with common sites including the lymph nodes, pleura, skin, ear, nose and throat, genitourinary system, pericardium, gastrointestinal tract, bones and joints, and central nervous system. Clinical manifestations of extrapulmonary TB are diverse and often non-specific. Diagnosis is based on a combination of clinical suspicion, imaging, histopathology, and microbiology. Treatment of extrapulmonary TB generally follows similar principles to pulmonary TB, but the duration of treatment depends on the site of involvement and the extent of the disease. Increased awareness among healthcare providers is essential for the timely recognition and effective management of extrapulmonary TB cases.

Adenosine deaminase from the cerebrospinal fluid for the diagnosis of tuberculous meningitis: A meta-analysis

OBJECTIVE

To comprehensively evaluate the diagnostic efficacy of adenosine deaminase in cerebrospinal fluid (CSF) for tuberculous meningitis (TBM), and the potential influence of patients' age groups and cutoffs of measured adenosine deaminase.

METHODS

Systematic review and meta-analysis of relevant studies retrieved from PubMed, Embase, and Web of Science databases. Pooled sensitivity and specificity were calculated with a random-effect model.

RESULTS

Overall, 43 studies with 1653 patients with TBM and 3417 controls without were included. Pooled results showed that adenosine deaminase in CSF is associated with satisfactory diagnostic efficacy for TBM, with a pooled sensitivity of 0.86 (95% confidence interval [CI]: 0.82-0.90), specificity of 0.89 (95% CI: 0.86-0.91), positive likelihood ratio of 7.70 (95% CI: 6.16-9.63), and negative likelihood ratio of 0.15 (95% CI: 0.12-0.20). The pooled receiver operating characteristic (AUC) was 0.94 (95% CI: 0.91-0.96), suggesting good performance. Subgroup analyses showed good diagnostic efficacies of adenosine deaminase in CSF for both adults (AUC 0.95) and children (AUC 0.96) with TBM. AUCs indicating the diagnostic accuracies of adenosine deaminase in CSF for TBM were 0.93 for studies with cutoffs <10 U/L and and 0.94 for a cutoff =10 U/L, but only 0.90 for studies with cutoffs >10 U/L.

CONCLUSIONS

Measuring adenosine deaminase of CSF shows satisfactory diagnostic efficacy for TBM in children and adults, particularly if using a cutoff ≤10 U/L.