Serum procalcitonin and C-reactive protein in the evaluation of bacterial infection in generalized pustular psoriasis

BACKGROUND: There is an obvious need for more prompt and specific biomarkers of bacterial infections in generalized pustular psoriasis patients. OBJECTIVE: The aim of this study was to evaluate the diagnostic properties and define appropriate cut-off values of procalcitonin and C-reactive protein in predicting bacterial infection in generalized pustular psoriasis patients. METHODS: Sixty-four generalized pustular psoriasis patients hospitalized from June 2014 to May 2017 were included in this retrospective study. The values of procalcitonin, C-reactive protein, details of infection, and other clinical parameters were analyzed. RESULTS: Receiver operating characteristic curve analysis generated similar areas (p=0.051) under the curve for procalcitonin 0.896 (95% CI 0.782-1.000) and C-reactive protein 0.748 (95% CI 0.613-0.883). A cut-off value of 1.50ng/mL for procalcitonin and 46.75mg/dL for C-reactive protein gave the best combination of sensitivity (75.0% for procalcitonin, 91.7% for C-reactive protein) and specificity (100% for procalcitonin, 53.8% for C-reactive protein). Procalcitonin was significantly positively correlated with C-reactive protein levels both in the infected (r=0.843, p=0.040) and non-infected group (r=0.799, p=0.000). STUDY LIMITATIONS: The sample size and the retrospective design are limitations. CONCLUSIONS: The serum levels of procalcitonin and C-reactive protein performed equally well to differentiate bacterial infection from non-infection in generalized pustular psoriasis patients. The reference value of procalcitonin and C-reactive protein applied to predicting bacterial infection in most clinical cases may not be suitable for generalized pustular psoriasis patients. C-reactive protein had better diagnostic sensitivity than procalcitonin; however, the specificity of procalcitonin was superior to that of C-reactive protein.