The Usefulness of Serum Leucine-rich Alpha-2 Glycoprotein As a Novel Biomarker in Monitoring Inflammatory Bowel Disease: a Systematic Review and Meta-analysis

Inflammatory bowel disease (IBD) is a condition of unknown origin. It does not have a definite cure and its response to various treatments can be evaluated based on symptom-based measures, invasive procedures, or biomarker levels, highlighting the need for an accurate biomarker. Since C-reactive protein (CRP) and fecal calprotectin have their shortcomings, the need for a novel biomarker remains critical. Systematic searches of PubMed, Scopus, Web of Science, and Embase were performed In January 2024. PROSPERO number is CRD42024507383. We assessed the accuracy of leucine-rich alpha-2 glycoprotein (LRG) in identifying disease activity among patients with IBD using a bivariate diagnostic random-effects model. Fourteen studies involving 1794 individuals conducted in Japan were selected for our systematic review. The sensitivity and specificity of LRG levels for detecting disease activity were analyzed in patients with IBD and in two subgroups (ulcerative colitis and Crohn's disease). The synthesized sensitivity and specificity were 75.4% [95% confidence interval (CI), 68.9-80.9%] and 77.3% (95% CI, 69.9-83.2%), respectively, in patients with IBD, 73.1% (95% CI, 62.7-81.5%) and 81.9% (95% CI, 73.9-87.8%), respectively, in patients with CD, and the secondary analysis of the ulcerative colitis subgroup showed a pooled sensitivity and specificity of 72.8 and 59.7%, respectively. Our systematic review and meta-analysis demonstrated that LRG could be useful in detecting IBD activity. It is superior for detecting disease activity, especially in patients with normal CRP levels. The LRG was more accurate in monitoring disease activity in patients with CD than in patients with IBD.