Comparison of the diagnostic performance of initial serum procalcitonin, lactate, and C-reactive protein for predicting bacteremia in female patients with acute pyelonephritis

ABSTRACT

OBJECTIVE: The purpose of the present study was to compare the diagnostic performance of initial procalcitonin, lactate, and high-sensitive C-reactive protein (hsCRP) for predicting bacteremia in female patients with acute pyelonephritis (APN). METHODS: We conducted a retrospective study of female APN patients who visited the emergency department (ED) at the studied hospital between January 2015 and December 2016. The main outcome was bacteremia, which was reported via the first blood culture at ED. The patient demographics, co-morbidities, physiologies, and laboratory variables including initial procalcitonin, lactate, and hsCRP levels, were collected and analyzed to identify associations with the presence of bacteremia. The area under the receiver operating curve (AUROC) and sensitivity (SE)/specificity (SP) were calculated for each variable. RESULTS: During the study period, 282 patients were enrolled. A total of 105 (37.2%) patients had bacteremia. Escherichia coli was the most frequent pathogen. The AUROC was 0.70 (0.63–0.76), 0.70 (0.63–0.76), and 0.56 (0.49–0.63) for the procalcitonin, lactate, and hsCRP, respectively. At a cut-off value of 0.163 ng/mL, the procalcitonin level predicted bacteremia, with a SE/SP of 95.2%/22.6%, respectively. At a cut-off value of 0.7 mmol/L, the lactate level predicted bacteremia with a SE/SP of 96.2%/20.9%, respectively. The combination of a procalcitonin level >0.447 ng/mL or a lactate level >0.7 mmo/L was chosen, as they showed 100% SE and a 100% negative predictive value. CONCLUSION: The initial serum procalcitonin and lactate levels showed similar and fair discriminative performance for predicting bacteremia in female APN patients, while the hsCRP level showed poor performance. The combination of procalcitonin and lactate (procalcitonin level≤0.447 ng/mL and lactate≤0.7 mmol/L) can be used to identify patients at low risk of bacteremia.