Background The positive rate of sputum bacteria in patients with pneumoconiosis complicated with pulmonary tuberculosis is lower than that in patients with simple tuberculosis, which makes the disease assessment more difficult.

Objective To compare the differences of blood test indexes between patients with pneumoconiosis complicated with bacteriologically negative and bacteriologically positive pulmonary tuberculosis, so as to provide a basis for the assessment of lesions in patients with pneumoconiosis complicated with pulmonary tuberculosis.

Methods The relevant information of 329 patients with pneumoconiosis complicated with tuberculosis diagnosed from 2010 to 2020 was retrospectively collected, including 260 cases of pneumoconiosis complicated with bacteriologically negative tuberculosis (B-TB) and 69 cases of pneumoconiosis complicated with bacteriologically positive tuberculosis (B+TB). The demographic characteristics and blood test indexes of the two groups of patients were analyzed and compared, and logistic regression analysis was conducted to identify factors associated with pneumoconiosis complicated with bacteriologically positive tuberculosis.

Results Body mass index (BMI) was significantly different between the two groups (P<0.05), and the proportion of BMI≤18.5 kg·m⁻² in the pneumoconiosis cases with B+TB was higher than those with B-TB. The levels of platelet count, fibrinogen, white blood cell count, neutrophil count, monocyte count, C-reactive protein, erythrocyte sedimentation rate, and D-dimer in the pneumoconiosis cases with B+TB were higher than those in the pneumoconiosis cases with B-TB (P<0.05); the levels of mean platelet volume, hemoglobin, albumin to globulin ratio, and high-density lipoprotein in the pneumoconiosis with B+TB group were lower than that in the pneumoconiosis with B-TB group (P<0.05). The abnormal rates of other indicators except mean platelet volume, fibrinogen, and high-density lipoprotein were higher in the pneumoconiosis with B+TB group than in the pneumoconiosis with B-TB group (P<0.05). The results of multiple logistic regression showed that C-reactive protein (OR=1.006, 95%CI: 1.001-1.010), platelet count (OR=1.004, 95%CI: 1.002-1.007), and monocyte count (OR=3.461, 95%CI: 1.370-8.745) were associated with positive sputum smear in patients with pneumoconiosis complicated with pulmonary tuberculosis (P<0.05).

Conclusion Some blood test indexes show differences between pneumoconiosis complicated with bacteriologically positive patients and pneumoconiosis complicated with bacteriologically-negative tuberculosis patients. C-reactive protein, platelet count, and monocyte count are factors associated with sputum positivity in pneumoconiosis complicated with tuberculosis patients. Monitoring selected indicators of blood test have a certain reference value for the assessment of lesions in patients with pneumoconiosis complicated with tuberculosis.