Usefulness of the Optimal Cutoff Value and Delta Value of Leucine-Rich Alpha 2 Glycoprotein in Ulcerative Colitis

BACKGROUND: Leucine-rich alpha 2 glycoprotein (LRG) is a novel serum biomarker used to determine disease activity in inflammatory bowel disease. We investigated the association between endoscopic scores based on the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) and LRG in ulcerative colitis (UC). METHODS: A total of 1019 LRG measurements were obtained from 358 patients with UC. This study included 190 patients (199 measurements) who underwent colonoscopy within 3 months before and after LRG measurement with unchanged disease status or treatment during the same period. The patients were divided into those with and without UC relapse. We evaluated the correlation between LRG levels and UCEIS scores and performed a receiver operating characteristic curve analysis to determine the optimal LRG cutoff value. Delta values of LRG were then analyzed. RESULTS: LRG levels were positively correlated with UCEIS scores (correlation coefficient: 0.638; 95% CI: 0.548–0.714; P < .0001) in all disease types. The LRG cutoff value for mucosal healing was 12.6 µg mL(−1) (area under the curve: 0.736; 95% CI: 0.651–0.821); this value had a sensitivity of 0.72 and a specificity of 0.66. In patients with UC relapse, the median delta value of LRG before and after relapse was 5 µg mL(−1). CONCLUSIONS: LRG levels were positively correlated with the UCEIS scores. The optimal LRG cutoff value for determining mucosal healing was 12.6 µg mL(−1). The median delta value of LRG before and after relapse was 5 µg mL(−1).