Neutrophil-to-lymphocyte ratio and its correlation with tuberculosis infection: a cross-sectional survey based on the NHANES database.

Background: Tuberculosis infection (TBI) is a major challenge to global public health. Early detection and treatment of TBI are crucial in preventing tuberculosis (TB). Although inflammation is closely linked to the pathogenesis of TBI, the neutrophil-to-lymphocyte ratio (NLR), as a new inflammatory marker, has been less studied with TBI risk. This study was based on the National Health and Nutrition Examination Survey (NHANES) database. We utilized a cross-sectional research method to explore the association between NLR and the risk of adult TBI, aiming to fill the blank in the studying relationship between NLR and TBI risk. Our findings may contribute to providing new biomarkers for the diagnosis and treatment of TBI. Methods: In this cross-sectional research, data from the NHANES database for the periods 1999-2000 and 2011-2012 were pooled for the study, with TBI as the dependent variable and NLR as the independent variable. A total of 2,433 participants were enrolled, including 391 TBI patients and 2,042 non-TBI patients. The inclusion criteria included information from complete blood testing and TBI status assessment. We evaluated demographic characteristics and clinical factors such as body mass index (BMI), smoking, drinking, NLR, and TBI risk. We employed weighted logistic regression to set up a relationship model between NLR and TBI and dissected the association between them through stratified analysis and subgroup analysis with confounding factors adjusted. We also utilized restricted cubic spline (RCS) and Kaplan-Meier (K-M) survival curves to investigate the nonlinear relationship between NLR and TBI, as well as their relationship with survival rates. Results: A total of 2,433 samples were included in this project, with 391 TBI patients and 2,042 non-TBI patients. In the multivariable weighted logistic regression model, an obvious negative association was observed between NLR and TBI risk [odds ratio (OR) <1, P<0.05], and it was substantially influenced by diabetes (P for interaction =0.049). The negative association between NLR and TBI risk was particularly remarkable (P<0.05) in male and hypertensive patients. The RCS curve indicated a potential linear relationship between NLR and TBI risk (P-non-linear =0.9561), with NLR >1.899, OR <1, being a protective factor. The K-M survival curve revealed an obvious linkage between high NLR (>2.328) and increased death risk in TBI patients. Conclusions: NLR is remarkably negatively linked with TBI risk. Patients with excessively high NLR have worse outcomes.