Procalcitonin levels predict acute kidney injury and prognosis in acute pancreatitis: a prospective study

Abstract

Background: Acute kidney injury (AKI) has been proposed as a leading cause of mortality for acute pancreatitis (AP) patients admitted to the intensive care unit (ICU). This study investigated the predictive value of procalcitonin (PCT) for AKI development and relevant prognosis in patients with AP, and compared PCT's predictive power with that of other inflammation-related variables.

Methods: Between January 2011 and March 2013, we enrolled 305 cases with acute pancreatitis admitted to ICU. Serum levels of PCT, serum amyloid A (SAA), interleukin-6 (IL-6), and C reactive protein (CRP) were determined on admission. Serum PCT was tested in patients who developed AKI on the day of AKI occurrence and on either day 28 after occurrence (for survivors) or on the day of death (for those who died within 28 days).

Results: Serum PCT levels were 100-fold higher in the AKI group than in the non-AKI group on the day of ICU admission (p<0.05). The area under the receiver-operating characteristic (ROC) curve of PCT for predicting AKI was 0.986, which was superior to SAA, CRP, and IL-6 (p<0.05). ROC analysis revealed all variables tested had lower predictive performance for AKI prognosis. The average serum PCT level on day 28 (2.67 (0.89, 7.99) ng/ml) was significantly (p<0.0001) lower than on the day of AKI occurrence (43.71 (19.24,65.69) ng/ml) in survivors, but the serum PCT level on death (63.73 (34.22,94.30) ng/ml) was higher than on the day of AKI occurrence (37.55 (18.70,74.12) ng/ml) in non-survivors, although there was no significant difference between the two days in the latter group (p = 0.1365).

Conclusion: Serum PCT is superior to CRP, IL-6, and SAA for predicting the development of AKI in patients with AP, and also can be used for dynamic evaluation of AKI prognosis.

Figure 1. Initial levels of infection markers in non-AKI and AKI patients.

The boxes indicate the interquartile range (IQR). The dark lines denote the median. The whiskers portray minimum and maximum values. Levels in the two groups were compared using the Wilcoxon rank sum test.

Figure 2. Receiver operating characteristic (ROC) curves for PCT, SAA, IL-6, and CRP for predicting AKI in AP.

Figure 3. Relative percentage of patients with PCT levels above and below the cutoff value, stratified by RIFLE classes.

The cutoff value for PCT levels was set at 3.30/ml. RIFLE = Risk, Injury, Failure, Loss, and End-stage kidney disease. P<0.001, Compared relative percentage between AKI(RIFLE class Risk, Injury, and Failure) and non-AKI(RIFLE 0) by chi-square test, and P = 0.832, among RIFLE class Risk, Injury, and Failure by the Cochran Armitage trend test.

Figure 4. PCT levels in patients stratified by RIFLE classes.

RIFLE = Risk, Injury, Failure, Loss, and End-stage kidney disease. PCT levels were compared between AKI (RIFLE classes Risk, Injury, and Failure) and non-AKI (RIFLE 0) patients using the Wilcoxon rank sum test, and PCT levels were compared among the RIFLE classes Risk, Injury, and Failure using the Kruskal-Wallis H test.

Figure 5. Initial levels of infective markers between AKI survivors and non-survivors.

The boxes indicate the interquartile range (IQR). The dark lines denote the median. The whiskers indicate minimum and maximum values. Marker levels were compared between the two groups using the Wilcoxon rank sum test.

Figure 6. Receiver operating characteristic (ROC) curves for PCT, SAA, IL-6, and CRP for AKI prognosis.

Figure 7. Figure 7. Relationship between serum PCT levels and prognosis.

A. The trend of serum PCT levels in survivors during the period from AKI occurrence to termination of follow up. B. The trend of PCT levels in non-survivors during the period from AKI occurrence to death. C. Serum PCT levels on the days of AKI occurrence and of termination of follow-up in survivors. D. Serum PCT levels on the days of AKI occurrence and of death in non-survivors. PCT levels of the two days were each compared using the Wilcoxon signed-rank test.