OBJECTIVES The aim of this study was to analyze changes in the extent of radiographic lesions with treatment in patients with pulmonary tuberculosis (TB) and, further, to identify clinical and radiographic factors related to radiographic response.

METHODS A prospective cohort study including patients with culture-proven pulmonary TB was performed. The posterior-anterior view films of the chest that had been taken at the time of diagnosis and at 6 months after the initiation of treatment were compared. We expressed the extents of the lesions as percentages involving the parenchyma compared with the remaining normal parenchyma.

RESULTS Among 135 patients enrolled, three failed to achieve smear conversion of sputa after 6 months of treatment. The extent of radiographic lesions decreased from 22.8% at the time of diagnosis to 10.5% after 6 months of treatment. Through the multiple regression model, we found that increasing age (p=0.034), previous history of TB (p=0.016), presence of cavity (p=0.016) or fibrotic lesion (p=0.009), and multidrug-resistant TB (p=0.002) were significantly associated with a poor radiographic response.

CONCLUSION Patients with less-prominent radiographic improvement and sustained negative tuberculous cultures of the sputa could be closely observed without ordering unnecessary chest radiographs or mycobacterial cultures as well as prolonging treatment.