Diagnostic value of procalcitonin in infections in patients with malignant hematologic diseases

The incidence of infections in patients with malignant hematologic diseases is extremely high and significantly affects their prognosis. Identifying early and precise biomarkers for infection is crucial for guiding the treatment of infections in these patients. Previous studies have shown that procalcitonin (PCT) can serve as an early diagnostic marker for bloodstream infections in patients with malignant hematologic diseases. This study aims to compare serum PCT levels in these patients with different pathogens, disease types, infection sites, and severity levels.

Clinical data and laboratory results of infected patients with malignant hematologic diseases treated at the Department of Hematology, the Third Xiangya Hospital of Central South University from January 2018 to August 2023 were collected. General patient information was retrospectively analyzed. Serum PCT levels were compared among patients with different pathogens, types of malignant hematologic diseases, infection sites, and infection severity; Receiver operator characteristic (ROC) curves were used to determine the cut-off values and diagnostic value of serum PCT levels in diagnosing bloodstream infections versus local infections and severe infections versus non-severe infections. Mortality rates after 4-7 days of anti-infective treatment were compared among groups with rising, falling, and unchanged PCT levels.

A total of 526 patients with malignant hematologic diseases were included. The main pathogens were Gram-negative bacteria (272 cases, 51.7%), followed by Gram-positive bacteria (120 cases, 22.8%), fungi (65 cases, 12.4%), viruses (23 cases, 4.4%), and mixed pathogens (46 cases, 8.7%). The main types of malignant hematologic diseases were acute myeloid leukemia (216 cases, 41.1%), acute lymphoblastic leukemia (107 cases, 20.3%), and lymphoma (93 cases, 17.7%). Granulocyte deficiency was present in 68.3% (359 cases) of the patients during infection, with severe infection in 24.1% (127 cases). Significant differences in serum PCT levels were found among patients with different types of pathogens (P<0.001), with the highest levels in Gram-negative bacterial infections. Significant differences in serum PCT levels were also found among patients with different types of malignant hematologic diseases (P<0.05), with the highest levels in lymphoma patients. Serum PCT levels were significantly higher in systemic infections and severe infections compared to local infections and non-severe infections (both P<0.001). ROC curve analysis showed that the cut-off values for diagnosing bloodstream infections and severe infections were 0.22 and 0.28 ng/mL, with areas under the curve of 0.670 and 0.673, respectively. After 4-7 days of anti-infective treatment, the mortality rates of the PCT declining, PCT unchanged, and PCT rising groups were 11.9%, 21.2%, and 35.7%, respectively, and pairwise comparisons were statistically significant (all P<0.05).

PCT can be used as an auxiliary indicator for early identification of different pathogens, infection sites, and severity levels in patients with malignant hematologic diseases combined with infections. Dynamic monitoring of PCT levels after empirical antibiotic treatment provides important guidance for assessing patient's prognosis.