Effects of chemoprophylaxis on minimal pulmonary tuberculosis lesions of doubtful activity

In mass radiographic surveys, minimal pulmonary lesions of tuberculous appearance but doubtful activity are often found in persons without symptoms of tuberculosis. Whether to treat such persons or merely keep them under observation is a problem, as many of them manifest tuberculosis subsequently. The New Delhi Tuberculosis Centre carried out a controlled study from 1958 to 1968 to study this question in the conditions prevailing in India. A randomly selected group of persons with this type of lesion was given isoniazid prophylaxis for 1 year, a control group of almost equal size receiving placebo during the same period. Both were regularly re-examined, radiologically and bacteriologically, over a period of 6 years, and persons who developed clinical tuberculosis were immediately referred to the appropriate treatment services.THE RESULTS SHOW THAT THE TREATED PATIENTS FARED MUCH BETTER THAN THOSE IN THE CONTROL GROUP: fewer of them developed tuberculosis and more of them showed radiological improvement. This superiority was maintained for at least 4 years beyond the treatment year. However, this advantage must be weighed against the comparative inacceptability of treatment by such persons and the consequent high cost of organizing the treatment. It is concluded that, except when special circumstances justify it, prophylaxis of this kind cannot be recommended as a routine procedure.