Ratio of monocytes to lymphocytes in peripheral blood in patients diagnosed with active tuberculosis

The ratio of monocytes to lymphocytes in peripheral blood could reflect an individual's immunity to Mycobacterium tuberculosis. The objective of this study was to evaluate the relationship between ratio of monocytes to lymphocytes and clinical status of patients with active tuberculosis.

This was a retrospective review of data collected from the clinical database of The Fifth People's Hospital of Wuxi, Medical College of Jiangnan University. A total of 419 patients who had newly diagnosed active tuberculosis and 108 cases from 419 patients with tuberculosis therapy either near completion or completed were selected. Controls were 327 healthy donors.

Median ratio of monocytes to lymphocytes was 0.36 (IQR, 0.22-0.54) in patients before treatment, and 0.16 (IQR, 0.12-0.20) in controls (p<0.001). Ratio of monocytes to lymphocytes <9% or >25% was significant predictors for active tuberculosis (OR=114.73, 95% CI, 39.80-330.71; OR=89.81, 95% CI, 53.18-151.68, respectively). After treatment, the median ratio of monocytes to lymphocytes recovered to be nearly normal. Compared to other patients, patients with extrapulmonary tuberculosis and of age >60 years were more likely to have extreme ratio of monocytes to lymphocytes (AOR=2.57, 95% CI, 1.08-6.09; AOR=4.36, 95% CI, 1.43-13.29, respectively).

Ratio of monocytes to lymphocytes <9% or >25% is predictive of active tuberculosis.