Predictive Value of C-reactive Protein and Kidney Computed Tomography in Patients with Acute Pyelonephritis

ABSTRACT

PURPOSE: This study was conducted to determine the predictive value of the C-reactive protein (CRP) and kidney computed tomography (CT) in the emergency department (ED) for predicting the severity of acute pyelonephritis. METHODS: One hundred thirty-nine patients who were diagnosed with acute pyelonephritis between January 2007 and June 2008 were enrolled in this study. The patient underwent a kidney CT in the ED and the CT findings were classified as normal, a focal wedge-shaped lesion, a multi-focal wedge-shaped lesion, a mass-effect lesion, and abscess formation. The symptoms, vital signs, past history, initial laboratory findings, serum CRP in the ED, and the length of the hospital stay based on the kidney CT grade in the ED were compared. RESULTS: Among the 139 patients, 138 were females and the mean age was 48.5+/-17.7 years. We classified the CT grades as follows grade 1, normal (n=20); grade 2, focal wedge-shaped lesion (n=25); grade 3, multi-focal wedgeshaped lesion (n=45); grade 4, mass-effect lesion (n=42); and grade 5, abscess formation (n=7). Statistically significant differences in leukocyte count, neutrophil ratio, ESR, CRP, and length of hospital stay existed between the CT grades. Patients were classified into two groups based on the CT grade (the mild group [grades 1 and 2], and the severe group [grades 3~5]). The leukocyte count, neutrophil ratio, ESR, CRP, maximal body temperature, duration of fever, duration of pyuria >3 days, and length of hospital stay were greater in the severe group. Based on the results of multivariate logistic regression analysis, the CRP level was shown to be an independent predictor that affected the severe group. The area under the ROC curve for CRP was 0.775 (95% CI, 0.695~0.854). CONCLUSION: The CRP level in the ED was an independent predictor that affected the severe group. Thus, the initial CRP level with the kidney CT grade may be used as a prognostic indicator of acute pyelonephritis in the ED.