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The diagnostic value of procalcitonin, WBC, and CRP in diagnosis of lower respiratory tract infections in elderly patients

Objective: Lower Respiratory Tract Infections (LRTI) in elderly patients hospitalized in Intensive Care Units (ICU) cause high morbidity and mortality. In this study; the prognostic value of CRP, WBC, and procalcitonin in respiratory infections were evaluated in elderly patients hospitalized in intensive care units.

Methods: Study population was included of 62 patients hospitalized in intensive care unit. All patients were intubated and received mechanic ventilation for more than ten days. Cultures and Gram stain of 62 bronchial aspiration samples of the patients sent to the Microbiology laboratory were evaluated. CRP, procalcitonin and WBC were measured. The diagnostic value of WBC, procalcitonin, and CRP were evaluated according to diagnostic standard. Clinical information and laboratory data were obtained from hospital medical records and evaluated retrospectively.

Results: On Gram stain of 30 samples, bacteria and >25 Polymorphonuclear Leukocytes (PMNs) were seen in every field. Also, samples were positive in quantitative culture with >100.000 cfu/ml. These samples were considered as purulent. The sensitivity, specificity, PPV and NPV for CRP were 100%, 3.1%, 49.1% and 100%, respectively. The sensitivity, specificity, PPD and NPV for procalcitonin were 73.3%, 31.2%, 50% and 55.5%, respectively. The sensitivity, specificity, PPD and NPV for WBC were 56%, 40%, 52% and 61.9% respectively. T-test was used in order to determine if the parameters vary in patients with purulent and not-purulent samples. According to t-test; CRP did not differ in two groups (p=0.346>0.05). Procalcitonin was not found useful for determining the purulence (p=0.772>0.05). No statistically significant difference was detected for WBC in two groups (p=0.559>0.05).

Author(s): Fatma Kalem, Suleyman Durmaz, Bilgen Ozdemir, Ayse Gul Ergun, Omur Ertugrul