Association between neutrophil-to-lymphocyte ratio and length of hospital stay in an acute psychiatric hospital: A cross-sectional study

Aim: The available evidence for predicting length of stay in acute psychiatric hospitals includes demographics, diagnosis, and treatment variables. This study aimed to evaluate the association between neutrophil-to-lymphocyte ratio (NLR) and length of hospital stay in an acute psychiatric hospital. Methods: A total of 116 patients who were admitted to an acute psychiatric ward at Urawa Neuropsychiatric Sanatorium (Saitama, Japan) from August 2022 to December 2022 were eligible for this study. Laboratory data of lymphocytes and neutrophils were assessed on the first day of admission and NLR was calculated based on the data. Participants were categorized into two groups, high NLR and low NLR, which were set as predictor variables, as well as using NLR as a continuous variable. Multiple linear regression was performed to determine the association between NLR and length of hospital stay, adjusting for confounding factors. Results: A total of 90 participants were included in this study. The association of NLR as a continuous variable and length of hospital stay was not significant. When we categorized participants into high- and low-NLR groups, the association was significant even after adjusting by covariates (p < 0.05). Conclusion: Categorized NLR was positively associated with the length of hospital stay in patients admitted to an acute psychiatric hospital. Categorized NLR may predict the length of hospital stay for patients who are admitted to an acute psychiatric hospital.