Combined neutrophil-to-lymphocyte, monocyte-to-lymphocyte, and platelet- to-lymphocyte ratios as inflammatory biomarkers in tuberculosis: A retrospective study from Lampang, Thailand

Background: Tuberculosis (TB) remains one of the major infectious diseases causing global morbidity and mortality. Systemic inflammation plays a central role in TB pathogenesis. Hematological indices derived from complete blood counts (CBC) including neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) have been proposed as surrogate inflammatory biomarkers. Objectives: To investigate the role of CBC-derived ratios (NLR, MLR, and PLR) as inflammatory biomarkers in TB patients compared with healthy controls, and to assess their association with clinical characteristics and laboratory findings. Materials and methods: This retrospective study was conducted at Lampang Hospital, Thailand. Data from 213 TB patients and 170 healthy controls were collected from medical records and hematology reports. CBC-derived ratios were calculated and analyzed using Mann-Whitney U test, multivariate logistic regression adjusted for age, gender, and body mass index (BMI), and receiver operating characteristic (ROC) curve analysis. Results: Median NLR, MLR, and PLR values were significantly higher in TB patients compared with controls (NLR 4.21 vs 1.58; MLR 0.47 vs 0.16; PLR 223.0vs119.9; all p