Plasma suPAR as a prognostic biological marker for ICU mortality in ARDS patients

Purpose: We investigated the prognostic value of plasma soluble urokinase plasminogen activator receptor (suPAR) on day 1 in patients with the acute respiratory distress syndrome (ARDS) for intensive care unit (ICU) mortality and compared it with established disease severity scores on day 1. Methods: suPAR was determined batchwise in plasma obtained within 24 h after admission. Results: 632 ARDS patients were included. Significantly (P = 0.02) higher median levels of suPAR were found with increasing severity of ARDS: 5.9 ng/ml [IQR 3.1–12.8] in mild ARDS (n = 82), 8.4 ng/ml [IQR 4.1–15.0] in moderate ARDS (n = 333), and 9.0 ng/ml [IQR 4.5–16.0] in severe ARDS (n = 217). Non-survivors had higher median levels of suPAR [12.5 ng/ml (IQR 5.1–19.5) vs. 7.4 ng/ml (3.9–13.6), P < 0.001]. The area under the receiver operator characteristic curve (ROC-AUC) for mortality of suPAR (0.62) was lower than the ROC-AUC of the APACHE IV score (0.72, P = 0.007), higher than that of the ARDS definition classification (0.53, P = 0.005), and did not differ from that of the SOFA score (0.68, P = 0.07) and the oxygenation index (OI) (0.58, P = 0.29). Plasma suPAR did not improve the discrimination of the established disease severity scores, but did improve net reclassification of the APACHE score (29 %), SOFA score (23 %), OI (38 %), and Berlin definition classification (39 %). Conclusion: As a single biological marker, the prognostic value for death of plasma suPAR in ARDS patients is low. Plasma suPAR, however, improves the net reclassification, suggesting a potential role for suPAR in ICU mortality prediction models.