Comparison of Chest X-Ray Findings of Smear Positive and Smear Negative Patients with Pulmonary Tuberculosis

BACKGROUND Tuberculosis is a chronic pulmonary infectious disease that has affected one-third of the people in the world. It causes nine million new cases and two million deaths per year. Chest radiography associated with Ziehl-Neelsen acid-fast staining procedure significantly helps the diagnosis of pulmonary tuberculosis (PTB). Chest radiography can help the diagnosis of tuberculosis in patients with a negative smear sample result that is mainly diagnosed with delay. OBJECTIVES In this study, chest X-ray findings of PTB were compared in two groups of smear positive and smear negative patients. PATIENTS AND METHODS In this retrospective descriptive-analytical study, 376 patients who had been confirmed with PTB were referred to Birjand Health Care Center from 2001 to 2006. Out of the 376 patients, 100 patients with a positive smear based on WHO criteria were selected. In addition, among negative smear patients, 100 were selected in whom similar demographic characteristics with positive smear patients were seen. All of them had undergone chest radiographies that were then interpreted by two expert radiologists independently. Moreover, all patients' sputa were examined by an expert laboratory technician at the reference laboratory of the health center. The obtained data were analyzed by means of frequency distribution table and descriptive statistics using SPSS (version 15) and Chi-square statistical test. RESULTS Except reticulo-nodular infiltration, the relative frequency of other radiographic findings in positive smear patients were more than negative smear patients; and only differences in calcification variables, mediastinal widening, patchy infiltration and hilar adenopathy were statistically significant (P < 0.05). CONCLUSIONS Based on the results of this study, although radiographic findings are not diagnostic in PTB, they are helpful if the assessment associates with the view of clinical manifestations and sputum smears.