Abstract
OBJECTIVE: This study aimed to evaluate the dynamics of the neutrophil-to-lymphocyte ratio (NLR) during the initial hospitalization of patients with eating disorders (EDs) and to assess its potential as a biomarker for monitoring disease severity and treatment response. METHODS: A retrospective chart review was conducted with 55 patients aged ≤ 16 years diagnosed with anorexia nervosa or avoidant/restrictive food intake disorder and admitted to Jichi Medical University Hospital between 2015 and 2021. Sociodemographic and clinical characteristics including sex, age, rate of weight gain, percentage of ideal body weight (%IBW), tube feeding treatment, and NLR were obtained. Statistical analyses used a mixed model for repeated measures to assess NLR changes regarding %IBW and other clinical factors. RESULTS: The NLR at admission was lower in the malnourished state but increased with weight recovery. MMRM revealed that tube feeding treatment (β = 0.538) and restoration of %IBW (β = 0.029) significantly predicted an increase in the NLR. The interaction between tube feeding and the quadratic term of %IBW was also significant, indicating distinct patterns of NLR changes: without tube feeding, NLR increased linearly with weight recovery, whereas with tube feeding, NLR exhibited a non-linear, upward-convex parabolic trend. DISCUSSION: These findings suggest that NLR may offer an objective recovery marker less influenced by patient self-report. Monitoring NLR before and after tube feeding may help distinguish true physiological recovery from transient stress responses, providing complementary information to conventional assessments. Further research is warranted to establish its clinical relevance.