Criteria for the diagnosis of pulmonary tuberculosis

Diagnostic criteria for pulmonary tuberculosis are presented in the form of a weighted diagnostic protocol. These criteria were evolved to standardize the diagnosis of pulmonary tuberculosis for a prospective study of the disease and its treatment, and were first tested in the evaluation of 469 referred patients, of whom 300 were found to have tuberculosis. The criteria have subsequently been validated clinically and statistically through their application to 1679 patients with radiological abnormalities suggestive of tuberculous disease, of whom 1154 were proved to have pulmonary tuberculosis. Application of these criteria whenever pulmonary tuberculosis is suspected has removed the dilemma often faced by clinicians when presented with a suggestive chest radiograph, a single sputum smear positive for acid-fast bacilli resembling Mycobacterium tuberculosis, or a strongly positive tuberculin test. We believe that these criteria put each of these separate findings into perspective. They allow the diagnosis of pulmonary tuberculosis to be made with confidence and prevent the erroneous diagnosis of non-tuberculous disease. Their use should alleviate the tendency towards an overdiagnosis of active pulmonary tuberculous disease, and thereby the waste of therapeutic and social resources.