Association Between NLR, MLR and Stroke Incidence, All-Cause Mortality Among Low-Income Aging Populations: A Prospective Cohort Study.

Objective: This study aimed to assess the association of the Neutrophil-to-Lymphocyte Ratio (NLR) and Monocyte-to-Lymphocyte Ratio (MLR) in predicting stroke incidence and all-cause mortality in low-income elderly populations. Methods: This prospective cohort study included participants who were middle-aged or elderly individuals from a low-income population in China. Participants were selected into the cohort and complete baseline assessments, which included questionnaire surveys, physical examinations, blood tests, and carotid artery ultrasound evaluations. Cox proportional hazards regression analysis was used to assess the associations of the NLR and MLR with the incidence of stroke and all-cause mortality. The predictive performance of the model was evaluated using the area under the receiver operating characteristic curve (AUC-ROC). Results: A total of 3948 participants were enrolled in the study. Over a median follow-up period of 7 years, 262 participants experienced stroke events and 227 participants died. After adjusting for potential confounding variables, the final model revealed that a higher NLR was significantly associated with an increased risk of stroke (HR: 1.776, 95% CI: 1.250-2.254, P = 0.001) and all-cause mortality (HR: 1.558, 95% CI: 1.148-2.116, P = 0.004). Furthermore, a higher MLR was found to be associated with an increased risk of all-cause mortality (HR: 1.397, 95% CI: 1.054-1.852, P = 0.020), but no significant association was observed between MLR and stroke incidence. ROC analysis revealed that the AUC for NLR in predicting stroke was 0.55 (95% CI: 0.52-0.59, P=0.005), while the AUC for MLR was 0.58 (95% CI: 0.54-0.62, P<0.001). Similarly, the AUC for NLR in predicting all-cause mortality was 0.57 (95% CI: 0.53-0.61, P<0.001), and the AUC for MLR was 0.61 (95% CI: 0.57-0.65, P<0.001). Conclusion: These findings indicate that NLR is associated with an increased risk of stroke and all-cause mortality, while higher MLR is associated with all-cause mortality but not with stroke incidence. However, the modest predictive performance of both markers suggests that their clinical utility remains limited. Further research is needed to validate these associations and explore their potential role in comprehensive risk assessment models.