Comparison of chest X-ray findings in smear-positive and smear-negative patients with pulmonary tuberculosis attending a tertiary care hospital in Bangladesh

Background: Tuberculosis (TB) continues to be a significant public health issue in Bangladesh and a significant number of people with active pulmonary TB (PTB) are sputum smear-negative, making chest radiography an important adjunctive diagnostic tool. The objective of this study was to compare the sociodemographic, clinical and chest radiographic profile of smear-positive and smear-negative PTB patients attending a tertiary care hospital in Bangladesh. Methods: This descriptive cross-sectional study was conducted at the Department of Medicine in Enam Medical College & Hospital, Dhaka, from January to June 2018 on 100 patients with pulmonary tuberculosis who were equally divided into 50 sputum smear-positive and 50 sputum smear-negative groups according to Ziehl-Neelsen staining. The Chi-square test was used to compare the sociodemographic data, clinical symptoms, erythrocyte sedimentation rate (ESR) and chest radiographic findings between the groups and a p value of less than 0.05 was regarded as statistically significant. Results: The two groups were mainly male, middle-aged and had no significant sociodemographic differences. Smear-positive patients were significantly more likely to have cough (100.0% vs 72.0%, p=0.001). Smear-positive patients had a higher rate of a raised ESR (>50 mm in the first hour) (50.0% vs 24.0%, p=0.007). Consolidation (56.0% vs 24.0%), inhomogeneous opacity (16.0% vs 4.0%), patchy opacity (32.0% vs 12.0%) and cavitary lesions (54.0% vs 22.0%) were all significantly more common in the smear-positive group (p<0.05), whereas nodular opacity, fibrosis, pleural effusion and collapse did not differ significantly between the groups. Conclusions: Pulmonary tuberculosis with smear positivity was associated with more frequent cough, raised ESR and consolidation and cavitation on chest radiography, suggesting that chest radiography is complementary to sputum microscopy in the diagnostic evaluation of pulmonary tuberculosis.