analysis of sputum smear and x-ray results in diagnosis of smear negative pulmonary tuberculosis

ABSTRACT

To study the role of chest x-ray in the diagnosis of sputum smear negative cases. Descriptive study. The study was carried out in the chest unit of Mayo hospital and PMRC TB research centre Lahore. A total of 220 suspects were analyzed for their AFB smear, culture from sputum and chest X-ray results. Sputum smear negative cases having findings consistent with TB on chest x-ray were matched with culture results for the final diagnosis. Sensitivity, specificity, negative and positive predictive values of the chest x-ray was determined in smear negative cases. Among 124 smear negative cases 85% with extensive lesion and 60% with moderate lesion were culture positive.. Among all 207 cases, the culture positivity was 91% among patients with extensive lesion and 72%in those having moderate lesions. The sensitivity and specificity of x-ray chest in sputum smear negative cases came out to be 94% and 68%, while positive and negative predictive values were 78% and 98%.There are various tools used for diagnosis of smear negative pulmonary TB some of these are expensive and are not available in high burden countries. In a poor resource setting x-ray chest and a course of 14 days antibiotics and clinical evaluation of the patient has been found useful in diagnosing sputum smear negative pulmonary TB cases