The value of computed tomography in discriminating malignant from non-malignant causes of unresolved unilateral pleural effusions: a systematic review

Our plain-English summary of The value of computed tomography in discriminating malignant from non-malignant causes of unresolved unilateral pleural effusions: a systematic review, by S. Reuter, T.M.H. Naur, P.F. Clementsen, et al (European Clinical Respiratory Journal, 2019).

The study

• Authors: S. Reuter, T.M.H. Naur, P.F. Clementsen, U. Bodtger
• Journal: European Clinical Respiratory Journal
• Published: 2019;6(1):1565803
• Type of article: Review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The scientific background in expert-opinion papers for recommending Computed Tomography (CT) in unilateral pleural exudates is based on studies including patients with other findings than unilateral pleural effusions or selected patients undergoing thoracoscopy. Therefore, we performed a systematic review investigating the sensitivity of CT for predicting malignancy in patients with unilateral, non-transudative, pleural effusions. A search strategy was developed with the assistance of a medical information specialist at our university library. We searched PubMed/MEDLINE, EMBASE and Cochrane Library, ClinicalTrials.gov and articles citing the included studies. No date restrictions were applied (the first included paper was published in 2001 (1)), and only literature in English was included. We used the Quality Assessment of Diagnostic Accuracy Studies 2 for bias assessment. We registered the protocol at PROSPERO (CRD42018094830). Five studies were included, two prospective and three retrospective, all performed in Western Europe. No study reported diagnostic values for patients with unilateral, non-transudative pleural effusions only; one study did for unilateral pleural effusions. In the remaining studies, most patients had unilateral effusions and non-transudative effusions. Patients were primarily males and >70 years. All but one study found a high incidence of malignancy, dominated by malignant pleural mesothelioma. All studies were limited by risk of bias and applicability, predominantly regarding study population, pretests and index test. The current evidence supporting the sensitivity of CT for predicting malignancy in unilateral pleural effusions (both non-transudative and all types of effusion) is very low and did not allow meta-analysis. Standardization of patient population and CT protocol may facilitate conclusions of futures studies.

© 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

In plain English

This systematic review examined how well chest computed tomography (CT) scans identify cancer as the cause of a pleural effusion (fluid around the lung) left unexplained after initial tests. The authors screened 23,980 records from several databases. Five studies, all from Spain or England, met their criteria. Patients in these studies were mainly men over 70. No study reported results for the group the review targeted: one-sided effusions that were not transudates. The single study limited to one-sided effusions reported that CT flagged 65% of the cancers. Across the studies, sensitivity (the share of cancers CT flagged) ranged from 64% to 92%, and specificity (the share of non-cancer cases correctly cleared) ranged from 75% to 100%. All but one study found a high rate of cancer, which the authors said suggested selection bias. Malignant pleural mesothelioma made up between 5% and 56% of the cancers, depending on the study. The studies were too different to combine in a meta-analysis. The authors concluded that the evidence for CT is sparse, and that prospective studies with well-defined criteria are needed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Systematic review of diagnostic accuracy studies (protocol registered at PROSPERO, CRD42018094830); risk of bias assessed with the QUADAS-2 tool; no meta-analysis was performed
• Who was studied: Five included studies of patients with pleural effusions: two prospective, two retrospective, and one with design not stated. They were performed in Spain or England between 2000 and 2016. Sample sizes were 126, 343, 370, 93 and 40 patients. Patients were primarily males over 70 years.
• Exposure: The test under study was chest CT (conventional or spiral), compared with pleural cytology or other tissue verification of malignancy. No asbestos or fiber exposure was studied.
• Main results:
  • Of 23,980 screened records, five studies were included
  • No study reported the sensitivity of CT for unilateral, non-transudative pleural effusions of unknown cause, which was the review's primary outcome
  • In the only study limited to unilateral effusions (Bintcliffe et al.), CT had a sensitivity of 65% for predicting a malignant cause
  • One study included both one-sided and two-sided effusions (Porcel et al.). In it, CT sensitivity for a malignant cause of non-transudative effusions was 74%, the same as for that study's whole group.
  • Across the studies, CT sensitivity ranged from 64% to 92% and specificity from 75% to 100%
  • The authors reported that all but one study found a high incidence of malignancy
  • In the Porcel et al. study (343 patients), the prevalence of malignancy was 34% (115 patients), and malignant pleural mesothelioma made up 5% (5) of the cancers
  • In the Traill et al. study (40 patients), the prevalence of malignancy was 80% (32 patients), and malignant pleural mesothelioma made up 56% (18) of the cancers
  • In the Bintcliffe et al. study (126 patients), the prevalence of malignancy was 46% (58 patients), and malignant pleural mesothelioma made up 31% (18) of the cancers
  • The evidence did not allow a meta-analysis
• The authors' conclusion: The authors concluded that the evidence for CT in this setting is sparse, and that the most relevant studies differ in design, data reporting and patient populations. They called for prospective studies with well-defined criteria for baseline work-up, patient population and CT protocol.
• Limitations the authors state:
  • Most included studies were retrospective, which the authors said leads to highly selected patient samples
  • The high prevalence of malignancy and malignant pleural mesothelioma in the included studies suggests selection bias
  • Biases related to CT could not be evaluated, because most studies did not describe the CT protocol or how scans were interpreted
  • All studies were done at tertiary centers in two Western European countries
  • No study evaluated the results of earlier tests (pleural fluid cytology and chest x-ray)

Topics

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Systematic Review, Exudate, Thoracoscopy, Pleural Mesothelioma, Meta-Analysis.

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