Diagnostic value of suPAR in differentiating noncardiac pleural effusions from cardiac pleural effusions.

INTRODUCTION: Soluble urokinase plasminogen activator receptor (suPAR) is a newly discovered inflammatory biomarker. suPAR has not been previously studied in differentiating noncardiac pleural effusion (PF) from cardiac PF. The aim of our study was to assess the diagnostic value of suPAR in PF.

METHODS: The concentration of PF-suPAR was measured by a commercialized enzyme-linked immunosorbent assay in a prospective cohort of 74 patients with PF, 18 patients with PF due to cardiac failure (CF) and 56 patients with noncardiac PF. The area under the curve quantified the overall diagnostic accuracy of the tests.

RESULTS: The median pleural fluid suPAR level was found as 23 (5.4-102.8) ng/mL. The median PF-suPAR level in CF was significantly lower than that of noncardiac effusions [11.8 (5.4-28.9) ng/mL vs 26.7 (8.2-102.8) ng/mL, respectively, P < 0.001]. The area under the receiver operating characteristic curve was 0.878 (95% confidence interval: 0795-0.962, P < 0.001) for noncardiac pleural fluid suPAR. The sensitivity, specificity and positive predictive value of PF-suPAR for noncardiac effusions at the cutoff level of ≥17.6 n/mL was 88%, 83% and 94%, respectively. The suPAR level in PF was found to correlate with all of the biochemical parameters of PF.

CONCLUSIONS: suPAR is a potential new marker for the discrimination between cardiac and noncardiac PF.