Diagnostic value of lymphocyte-to-monocyte ratio in Crohn's disease: a cross-sectional study

Investigating non-invasive laboratory biomarkers for detecting and classifying Crohn's disease (CD) activity remains challenging. Here, we aimed to evaluate the diagnostic efficacy of immunological biomarkers in identifying disease activity in newly diagnosed CD patients.

This cross-sectional study was performed from October 2022 to July 2023 and included 20 healthy participants and 46 confirmed newly diagnosed CD patients in a Teaching Hospital for Gastroenterology and Hepatology, Sulaimani, Iraq. The patients were categorized according to the disease activity assessed according to the Harvey-Bradshaw Index and divided into remission and active CD.

A statistically higher serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels were found among the remission CD group (P = 0.005 and P = 0.0002, respectively) and active CD group (P < 0.0001 and P < 0.0001, respectively) compared to the healthy controls. Moreover, the mean CRP and ESR levels among active CD were also considerably higher than those of remission CD (P = 0.018 and P = 0.005, respectively). The lymphocyte-to-monocyte ratio (LMR) was significantly lower in patients with active disease (3.01 ± 1.36) than in remission patients (6.77 ± 2.17) (cutoff < 4.42, area under receiver-operating characteristic curve (ROC) = 0.807, 95% CI, 77.35-98.73%, 93% sensitivity, and 78% specificity). Although the neutrophil-to-lymphocyte ratio (NLR) was significantly elevated in active patients (3.64 ± 2.004) compared to healthy controls (1.91 ± 0.48; P = 0.0001), it is not usable for disease activity or severity as the area under the ROC curve was 0.68 (95% CI, 52.22-85.08%, sensitivity = 79%, specificity = 62%).

The LMR can be an affordable, easily accessible test that shows promise for determining disease activity in newly diagnosed CD patients.