Pneumonia is one of the leading causes of death in the intensive care unit (ICU). Many biomarkers for predicted prognosis have been suggested; among these, procalcitonin (PCT) is known to increase in cases of bacterial infection. However, there have been many debates regarding whether PCT is an appropriate prognostic marker for pneumonia. Therefore, we investigated whether PCT can serve as a biomarker for pneumonia, and compared it with CURB-65, which is a known tool for predicting the prognosis of pneumonia.

Levels of PCT and CURB-65 scores were compared between 30-day non-survival (n = 30) and survival (n = 101) patients. Relationships between PCT and CURB-65 were determined by using linear regression analysis, as well as by using receiver operating characteristic (ROC) curve analysis and calculation of the area under the curve (AUC). High and low PCT groups were compared.

High PCT and high CURB-65 score were positively associated with 30-day mortality. For the prediction of 30-day mortality, initial PCT and CURB-65 exhibited AUCs of 0.63 and 0.66; these were not significantly different (P = 0.132). We found that the high PCT group had a higher rate of initial treatment failure (91%, P = 0.004).

Initial PCT can be a prognostic biomarker for mortality in severe pneumonia, similar to the CURB-65 score. Initial high PCT was positively associated with initial treatment failure.

Serum procalcitonin (PCT) is a specific biomarker that rises after bacterial infection, and levels of PCT are known to correlate with the severity and mortality of patients with pneumonia and sepsis. However, the usefulness of PCT levels in acute pyelonephritis is unknown. This study aimed to evaluate the effectiveness of using the PCT level as a predictive test for bacteremia in acute pyelonephritis.

Between January 2012 and June 2013, 140 patients diagnosed with acute pyelonephritis were admitted to Haeundae Paik Hospital. Serum PCT, C-reactive protein (CRP), and white blood cell (WBC) levels at pre- and post- treatment were measured. Blood and urine cultures were obtained from all patients. The levels of PCT, CRP, and WBCs were each compared between the blood culture-positive and blood culture-negative groups to assess their effectiveness in predicting bacteremia.

Pre-treatment PCT level was 0.77 ng/mL (95% CI: 0.42–1.60 ng/mL) in the blood culture-negative group and 4.89 ng/mL (95% CI: 2.88–9.04 ng/mL) in the blood culture-positive group, and the increase between the two groups was statistically significant. The area under the receiver operating characteristic curve of PCT level for prediction of bacteremia was 0.728. A cut-off value of 1.23 ng/mL indicated a sensitivity of 79.0 % and specificity of 60.0 % for PCT level.

Serum PCT level is a useful predictive test for bacteremia in acute pyelonephritis. Through the early detection of bacteremia, serum PCT level can help estimate the prognosis and predict complications such as sepsis.