Advancement in pleura effusion diagnosis: a systematic review and meta-analysis of point-of-care ultrasound versus radiographic thoracic imaging

Abstract

Background: Pleural effusion is a fluid buildup in the pleural space that mostly result from congestive heart failure, bacterial pneumonia, malignancy, and pulmonary embolism. The diagnosis of this condition can be challenging as it presents symptoms that may overlap with other conditions; therefore, imaging diagnostic tools such as chest x-ray/radiograph (CXR), point-of-care ultrasound (POCUS), and computed tomography (CT) have been employed to make an accurate diagnosis. Although POCUS has high diagnostic accuracy, it is yet to be considered a first-line diagnostic tool as most physicians use radiography. Therefore, the current meta-analysis was designed to compare POCUS to chest radiography.

Methods: n extended search for studies related to our topic was done on five electronic databases, including PubMed, Medline, Embase, Scopus, and Google Scholar. A quality assessment using the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) was performed on all eligible articles obtained from the databases. Moreover, the diagnostic accuracy of POCUS and CXR was performed using STATA 16 software.

Results: Our search yielded 1642 articles, of which only 18 were eligible for inclusion and analysis. The pooled analysis showed that POCUS had a higher diagnostic accuracy compared to CXR (94.54% (95% CI 91.74-97.34) vs. 67.68% (95% CI 58.29-77.08) and 97.88% (95% CI 95.77-99.99) vs. 85.30% (95% CI 80.06-90.54) sensitivity and specificity, respectively). A subgroup analysis based on the position of patients during examinations showed that POCUS carried out in supine and upright positions had higher specificity than other POCUS positions (99%). In comparison, lateral decubitus CXR had higher sensitivity (96%) and specificity (99%) than the other CXR positions. Further subgroup analyses demonstrated that CXR had higher specificity in studies that included more than 100 patients (92.74% (95% CI 85.41-100). Moreover, CXR tends to have a higher diagnostic accuracy when other CXR positions are used as reference tests (93.38% (95% CI 86.30-100) and 98.51% (95% CI 94.65-100) sensitivity and specificity, respectively).

Conclusion: POCUS as an imaging modality has higher diagnostic accuracy than CXR in detecting pleural effusion. Moreover, the accuracy is still high even when performed by physicians with less POCUS training. Therefore, we suggest it is considered a first-line imaging tool for diagnosing pleural effusion at the patients' bedside.

Keywords: Chest X-ray; Diagnostic imaging; Emergency medicine; Meta-analysis; Pleural effusion; Point-of-care systems; Sensitivity; Specificity; Systematic review; Ultrasound.

Fig. 1

PRISMA flow diagram for study selection

Fig. 2

QUADAS-2 risk of bias summary

Fig. 3

Forest plot showing the sensitivity of POCUS in detecting pleural effusion according to the patients’ position during examination

Fig. 4

Forest plot showing the specificity of POCUS in detecting pleural effusion according to the patients’ position during examination

Fig. 5

Forest plot showing the sensitivity of CXR in detecting pleural effusion according to the patients’ position during examination

Fig. 6

Forest plot showing the specificity of POCUS in detecting pleural effusion according to the patients’ position during examination