Background: Proenkephalin A 119-159 (penKid) has been proposed as a sensitive biomarker of renal function. This study evaluated the association of concentrations of plasma penKid with death and risk of acute kidney injury (AKI) in severely ill burn patients.
Methods: A prospective observational study in two centers with severely ill adult burn patients was conducted. The inclusion criteria were total body surface area (TBSA) burns >15%, with burn injury occurring <72 h before intensive care unit (ICU) admission and plasma sample taken at admission. The primary endpoint was 90-day mortality. The secondary endpoints were AKI and a combined endpoint of 90-day mortality and/or AKI. Mortality was also evaluated in the sub-group of patients with sub-clinical AKI, defined as a patient without AKI but with elevated penKid.
Results: A total of 113 consecutive patients were enrolled. The median age was 48 years (Interquartile range [IQR] 33-64), the median burn TBSA was 35% (IQR 25-53), and 90-day mortality was 31.9%. Thirty-one percent of the patients had AKI, and 41.6% of patients had the combined endpoint. There was a stepwise decrease in survival from patients without AKI, sub-AKI, and with AKI (survival rate 90.0% [95% CI 82.7-97.9], 66.7% [95% CI 48.1-92.4], and 31.4% [95% CI 19.3-51.3], respectively, p < 0.001). Plasma penKid concentration was significantly higher in non-survivors compared to survivors (86.9 pmol/L [IQR 53.3-166.1] versus 52.9 pmol/L [IQR 37.1-70.7]; p = 0.0001) and in patients with AKI compared to patients without AKI (86.4 pmol/L [IQR 56.5-153.4] versus 52.5 pmol/L [IQR 35.5-71.2]; p < 0.001). Penkid provided added value on top of serum creatinine (Screat) and Sepsis Related Organ Failure Assessment (SOFA) scores to predict 90-day mortality (combined c-index of 0.738 versus 0.707; p = 0.024 and 0.787 versus 0.752; p < 0.001).
Conclusions: Plasma penKid concentration at admission was associated with an increased risk of death in burn patients. PenKid has additional prognostic value on top of Screat and SOFA to predict 90-day mortality.
Keywords: Acute kidney injury; Biomarkers; Burn patients; Mortality; Proenkephalin.
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