The Prognostic Value of the Neutrophil-to-lymphocyte Ratio in Older Patients with Pulmonary Tuberculosis

Objective The neutrophil-to-lymphocyte ratio (NLR) is a readily available biomarker associated with the prognosis of several diseases. However, the available studies investigating the association between NLR and prognosis in older patients with pulmonary tuberculosis (PTB) are insufficient. We aimed to clarify the association between the peripheral NLR and the prognosis in older patients with PTB. Methods We retrospectively examined 115 PTB patients aged ≥65 years. Pretreatment blood tests and chest computed tomography were performed to assess mortality at 30 and 365 days after treatment initiation (Day30 and Day365). Results NLR was an associated factor of mortality at Day30 after adjusting for the serum hemoglobin and albumin levels [odds ratio (OR), 1.13; 95% confidence interval (CI), 1.03-1.24]. However, no significant association was found between NLR and mortality at Day365 (OR, 1.04; 95% CI, 0.956-1.13). To evaluate the usefulness of NLR in predicting mortality on Day30, we analyzed the receiver operating characteristic (ROC) curve. The area under the curve of the NLR was 0.831 (95% CI, 0.733-0.929). Using an ROC curve analysis, we determined that the effective cut-off value of the NLR for predicting prognosis was 5.664 (sensitivity, 67.0%; specificity, 88.9%). We divided the patients into two groups based on the previously mentioned cut-off values. The survival rate at 30 days was significantly lower in the group with an NLR≥5.664 than in the group with an NLR<5.664. Conclusion The NLR may be a useful predictive factor for the short-term prognosis in older patients with PTB.