Semi-quantitative Procalcitonin Test for the Diagnosis of Bacterial Infection: Clinical Use and Experience in Japan

Abstract

The efficacy of the rapid semi-quantitative procalcitonin (PCT) test for the diagnosis of bacterial infection was evaluated in patients with systemic inflammatory response syndrome. A retrospective observational study was performed from June to December 2008 at the Chugoku Rosai General Hospital, Japan. This study analyzed consecutive patients (both outpatients and inpatients) who developed systemic inflammatory response syndrome and whose PCT test was measured semi-quantitatively within 24 hours of onset, or at the first hospital visit. Based on the clinical diagnosis, the patients were divided into two groups. Group I comprised patients with a bacterial infection, and group II comprised patients with a non-bacterial infection, or non-infectious disease. Receiver operating characteristic curves were used to evaluate the diagnostic value of the semi-quantitative PCT test kit, C-reactive protein levels and white blood cells counts for the detection of bacterial infections, and the areas under the resulting curves were compared. A total of 168 patients were included and divided into groups I (n=112) and II (n=56). Group I showed a significantly higher percentage of positive PCT tests (≥ 0.5 ng/mL) than group II (67.8%vs. 19.6%, p < 0.001). PCT showed a sensitivity of 67.8% [95% confidence interval (CI)=58.4-76.4] and a specificity of 80.4% (95% CI=67.6-89.8). The areas under the resulting curves for PCT (0.764) were significantly larger than those seen for C-reactive protein (0.650, p=0.02) and white blood cells (0.618, p=0.006). The semi-quantitative PCT test is as useful for distinguishing bacterial infection from other inflammatory diseases in common clinical practice as the quantitative PCT.