Diagnostic Value of Procalcitonin and C reactive Protein for Infection and Sepsis in Elderly Patients.

Introduction Biomarkers are useful for diagnosing infection and sepsis in adults, but data are limited in elderly patients. Furthermore, clinical symptoms of infection in elderly patients are usually atypical or unclear. We aimed to assess the usefulness of PCT, CRP, and WBC in distinguishing elderly patients infected with sepsis from infected without sepsis and those with no infection. We also aimed to find a cut-off value for diagnosing sepsis and infection without sepsis in elderly critically ill patients. Methods In this single-center and prospective observational study, patients older than 65 years were enrolled. Serum levels of PCT, CRP, and WBC were measured within 24 hours. Patients were allocated into sepsis(S), infected without sepsis (IWS), and no-infection (NI) groups. Data were analyzed with Mann-Whitney?s U test and Kruskal- Wallis test. The Receiver Operating Characteristic (ROC) curves were used to assess the accuracies of the biomarkers in diagnosing IWS and S. Results We analyzed 188 patients with a mean age of 77,05 ±7.4 in the study; 95 (50.5%) of them were women. 64 (34%) of whom were classified as IWS, 29 (15%) as S, and 95 (50.5%) as NI group. There were significant differences in the PCT, CRP levels between the IWS and NI, S and NI (p<0. 001, p<0.001, p< 0.001, p<0.01, respectively). The PCT levels were significantly different when the NI group was compared to IWS (p<0.001) and S (p<0.001) groups. The CRP levels were also different when the NI group was compared to both IWS (p<0.001) and S (p<0.001). PCT was significantly higher in S compared to IWS (p<0.001), while CRP and WBC were not (p< 0.80, p<0.07, respectively). The value of PCT for discrimination of patients with IWS was highest with an AUC of 0.886, followed by CRP (AUC = 0.787; p<0.001), and WBC (AUC = 0.695; p<0.001). PCT also yielded the highest value for discrimination of patients with S with an AUC of 0.994, followed by CRP (AUC = 0.795:p<0.001) and WBC (AUC=0.768,p<0.01). The PCT cut-off values were 0.485?/L and 1.245 ?g / L for the discrimination of patients with IWS and S, respectively. The cut-off values of CRP level were 59.45 mg / L and 57.50 mg/L for infected without sepsis and sepsis, respectively. Conclusions PCT was found to be a more valuable marker than CRP and WBC for the discrimination of elderly patients with infected without sepsis and sepsis.