Diagnostic performance of C-reactive protein for parapneumonic pleural effusion: a meta-analysis

Abstract

Background: Parapneumonic pleural effusion (PPE) refers to effusion secondary to lung infection, the accurate diagnosis of which remains a clinical challenge. Many studies have suggested that the C-reactive protein (CRP) may be useful for diagnosing PPE, but the results have varied. This study aimed to summarize the overall diagnostic ability of serum/pleural CRP for PPE through a meta-analysis.

Methods: Eligible studies were searched for within PubMed, EMBASE, and other databases up to March 1, 2018. The main diagnostic indexes, sensitivity, specificity, positive likelihood ratio/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR), were then pooled from the individual studies. The summary receiver operating characteristic curves and area under the curve (AUC) were used to summarize the overall test performance.

Results: Eighteen publications were included in this meta-analysis. Summary estimates of the diagnostic performance of pleural CRP for PPE were as follows: sensitivity, 0.80; specificity, 0.82; PLR, 4.51; NLR, 0.25; DOR, 18.26; and AUC, 0.88. The AUC of serum CRP in diagnosing PPE was 0.79. The diagnostic indexes for pleural CRP in differentiating complicated PPE (CPPE) from uncomplicated PPE were as follows: sensitivity, 0.65; specificity, 0.85; PLR, 4.26; NLR, 0.41; DOR, 10.38; and AUC, 0.83. There was no evidence of publication bias.

Conclusions: Both serum and pleural CRP help to diagnose PPE but with moderate diagnostic ability. Pleural CRP measurements also can aid in differentiating CPPE from uncomplicated PPE. However, the results of the CRP assay should be interpreted with additional biomarker tests.

Keywords: C-reactive protein (CRP); complicated parapneumonic pleural effusion (CPPE); diagnosis; meta-analysis; parapneumonic pleural effusion (PPE).

Figure 1

Quality assessment of individual studies in terms of risk of bias and applicability concerns based on the Quality Assessment of Diagnostic Accuracy Studies-2.

Figure 2

Diagnostic performance of pleural CRP for parapneumonic pleural effusions. CRP, C-reactive protein. (A) Forest plot of sensitivity for pleural CRP in diagnosing parapneumonic pleural effusions; (B) forest plot of specificity for pleural CRP in diagnosing parapneumonic pleural effusions; (C) the SROC curve of pleural CRP for the diagnosis of parapneumonic pleural effusions, the AUC was 0.88. SROC, summary receiver operating characteristic; AUC, area under the curve; CRP, C-reactive protein.

Figure 3

Diagnostic performance of serum CRP for parapneumonic pleural effusions. (A) Forest plot of sensitivity for serum CRP in diagnosing parapneumonic pleural effusions; (B) forest plot of specificity for serum CRP in diagnosing parapneumonic pleural effusions; (C) the SROC curve of serum CRP for the diagnosis of parapneumonic pleural effusions, the AUC was 0.79. SROC, summary receiver operating characteristic; AUC, area under the curve; CRP, C-reactive protein.

Figure 4

Diagnostic performance of pleural CRP for complicated parapneumonic pleural effusions. (A) Forest plot of sensitivity for pleural CRP in diagnosing complicated parapneumonic pleural effusions; (B) forest plot of specificity for pleural CRP in diagnosing complicated parapneumonic pleural effusions; (C) the SROC curve of pleural CRP for the diagnosis of complicated parapneumonic pleural effusions, the AUC was 0.83. SROC, summary receiver operating characteristic; AUC, area under the curve; CRP, C-reactive protein.

Figure 5

Funnel plots for assessing the risk of publication bias. Publication bias in studies assessing the role of pleural CRP for the diagnosis of parapneumonic pleural effusions, P=0.31. CRP, C-reactive protein.

Figure S1

Flow diagram of study selection.