Evaluation of Serum Leucine-Rich Alpha-2 Glycoprotein Levels in Inflammatory Bowel Disease Patients across Racial...

Serum leucine-rich alpha-2 glycoprotein (LRG) has emerged as a novel biomarker for inflammatory bowel disease (IBD). However, its clinical utility among non-Japanese populations has not been investigated. This study aimed to validate the diagnostic ability of serum LRG in non-Japanese patients with IBD.

A retrospective cross-sectional study was conducted, including patients with IBD who underwent at least one serum LRG measurement between 2020 and 2023. Correlations between serum LRG and C-reactive protein (CRP) levels were independently evaluated in Japanese and non-Japanese cohorts. The association between endoscopic activity and serum LRG levels was investigated, and the diagnostic performance of LRG for detecting endoscopic activity was evaluated using receiver operating characteristic (ROC) analysis.

Serum LRG levels were measured at 11,730 time points for 2,500 Japanese patients and 276 time points for 58 non-Japanese patients. Among non-Japanese patients, 53% were Asian, 37% White, 4% Black, and 6% other racial backgrounds. The correlation between LRG and CRP was similarly robust in non-Japanese (r = 0.64) and Japanese (r = 0.64) patients. Among non-Japanese, serum LRG levels in endoscopic remission were significantly lower than those in active disease (p = 0.0228). The area under the ROC curve of LRG for endoscopically active disease in ulcerative colitis (n = 46) was 0.79 (95% confidence interval [CI], 0.60-0.98), numerically higher than that of CRP at 0.69 (95% CI, 0.55-0.84).

Serum LRG demonstrates consistent diagnostic value in both Japanese and non-Japanese patients with IBD, supporting its broader clinical applicability across diverse populations.