Objective: To determine if the level of serum C-reactive protein (CRP) can be used to differentiate between inflammatory diarrhea and non-inflammatory diarrhea in patients with acute infectious diarrhea or acute gastrointestinal infection.
Methods: This was a retrospective study based on medical records from a single military hospital located in Daejeon, Republic of Korea. The records of 1,085 patients who presented with abdominal pain, fever (≥ 37.8 °C), and diarrhea between May 2008 and May 2011 were reviewed, and 538 patients were selected. The eligible patients had undergone abdominal contrast tomography (CT) or colonoscopy within 3 days and blood sampling on the day of admission. The selected patients were divided into two groups on the basis of their abdominal CT or colonoscopy findings: group A, the inflammatory diarrhea group (n = 234), and group B, the non-inflammatory diarrhea group (n = 304). We then compared the clinical and laboratory characteristics of these two groups.
Results: Erythrocyte sedimentation rate and CRP levels were significantly higher in group A (inflammatory diarrhea) patients than group B (non-inflammatory diarrhea) patients (16.47 ± 5.46 vs. 15.29 ± 5.72 (P < 0.05), respectively, and 4.92 ± 2.49 vs. 1.79 ± 0.95 (P < 0.05), respectively). Multivariate analysis revealed that CRP level on admission was the most important predictor of inflammatory diarrhea (OR 7.39, P < 0.05). Receiver operating characteristic analysis results also showed that CRP had the highest area-under-the-curve value (0.91; 95 % confidence interval 0.88-0.93; P < 0.05) for distinguishing inflammatory diarrhea from non-inflammatory diarrhea. At a cut-off level of 3.08 mg/dL, CRP had a sensitivity of 82 % and a specificity of 85 %.
Conclusions: CRP as a diagnostic marker of inflammatory diarrhea was superior to the other inflammatory markers and clinical characteristics we evaluated in this study. A patient's CRP level on admission may aid clinical decision-making, for example initiating empiric antibiotics therapy and/or performing additional clinical tests.