RESUMO
OBJECTIVE: To examine the peripheral monocyte to lymphocyte ratio (ML ratio) of patients with tuberculous (TB) pleuritis and the ML ratio changes after treatment. METHODS: Clinical and laboratory information were collected from patients with lymphocytic exudative pleural effusion admitted to Chiang Mai University Hospital from 2013 to 2019. This study compared the ML ratios between tuberculous pleuritis and other diagnoses in patients who were followed after treatment. RESULTS: A total of 152 patients were included: 57 with tuberculous pleuritis and 95 with other lymphocytic exudates. The majority of non-tuberculous effusion was malignant pleural effusion. The mean ML ratio of each group was 0.72±0.29 and 0.34±0.13 (p<0.001). The Area Under the Receiver Operative Characteristic Curve of the ML ratio for diagnosing tuberculous pleuritis was 0.91. The best cut-off point of the ML ratio for diagnosing tuberculous pleuritis was >0.45, where the sensitivity and specificity were 82.5% and 86.3%, respectively. The ML ratio gradually reduced after the anti-TB treatment. ML ratios at 0, 2, and 6 months after the treatment were 0.72±0.29, 0.40±0.37, and 0.30±0.27, respectively (p<0.001). CONCLUSION: The peripheral blood ML ratio is an easy and useful tool for diagnosing and predicting the treatment response in patients with tuberculous pleuritis.