Background: At present, the most direct method to evaluate mucosal healing in patients with ulcerative colitis (UC) is endoscopy, but it is costly and invasive. Therefore, it is necessary to find a biomarker with low cost, easy access, high sensitivity and specificity as an indicator of UC activity. This study aimed to examine the level of platelet to lymphocyte ratio (PLR) and interleukin-8 (IL-8) in UC patients and evaluate their roles in differential diagnosis and disease activity assessment.
Methods: A retrospective study involving 130 UC patients and 141 irritable bowel syndrome (IBS) patients was performed. The UC patients were divided into remission group and active group according to the Modified Mayo score. The receiver operating characteristic curve (ROC) analysis was performed to determine the optimal cutoff value of PLR and IL-8 in differential diagnosis between UC patients and IBS patients.
Results: The levels of WBC, PLR, and IL-8 in UC patients were higher than those compared with IBS controls. The optimal cutoff to differentiate UC and IBS patients was 6.76 109/L, 114.70, and 19.42 pg/mL for WBC, PLR, and IL-8, respectively (sensitivity, 36.9% vs. 83.8% vs. 72.3%; specificity, 83.0% vs. 65.2% vs. 94.3%; AUC, 0.601 vs. 0.815 vs. 0.859). IL-8 had the highest AUC and specificity. Among 130 patients, 75 patients (57.6%) had mucosal inflammation. The cutoff value of IL-8 for predicting disease severity of UC patients was 22.21 pg/mL (AUC: 0.861). The sensitivity, specificity, and Youden index of IL-8 for predicting severe UC were 92.0%, 81.8%, and 0.702, respectively.
Conclusions: PLR and IL-8 showed great performance in distinguishing UC from IBS patients. Moreover, elevated IL-8 level indicated mucosal inflammation, reflecting disease severity in UC patients.