Neutrophil-lymphocyte ratio as a predictor of early treatment response in adolescent females with obsessive-compulsive disorder

Adolescence is a critical period for the onset of obsessive-compulsive disorder (OCD), in which inflammatory markers such as the neutrophil-lymphocyte ratio (NLR) may influence disease development. However, the impact of these markers on early clinical improvement remains unexplored. This study aimed to identify factors associated with early clinical improvement in adolescent females with OCD, with particular focus on baseline inflammatory markers. This retrospective analysis included 99 female patients (aged ≤ 18 years) diagnosed with OCD and admitted between 2011 and 2024 at a tertiary psychiatric hospital in China. Clinical and demographic characteristics, medication usage, and baseline blood routine results were extracted from electronic records. Inflammatory markers including the NLR were calculated. Early treatment response was assessed using the Clinical Global Impressions scale. Variables with p < 0.1 in univariate analysis were entered into a binary logistic regression model to identify predictors of early treatment response. Bootstrap internal validation with 1000 resamples was performed to assess model stability. Among the 99 patients, 50.51% showed early clinical improvement at two weeks. Binary logistic regression identified baseline NLR ( odds ratio = 0.173, 95% confidence interval = [0.060 to 0.496]; p = 0.001) and sodium valproate use ( odds ratio = 0.056, 95% confidence interval = [0.005 to 0.581]; p = 0.016) as independent predictors of early clinical improvement. Bootstrap validation confirmed model robustness (optimism‑corrected C‑statistic = 0.803), the combined model incorporating NLR and sodium valproate achieved good discriminative ability ( area under the curve = 0.823). Higher baseline NLR and sodium valproate use are associated with poorer early clinical improvement during the first two weeks of hospitalization in adolescent females with OCD. These findings highlight the potential utility of NLR as a prognostic marker and underscore the need for individualized medication selection in this population. Further prospective studies with larger samples are warranted to validate these results and clarify the underlying mechanisms. The trial was registered in the Chinese Clinical Trial Registry (ChiCTR2400093247) on 29 November 2024.