Preventive therapy with isoniazid for 'inactive' tuberculosis

Abstract

The protective effect of preventive therapy among previously untreated persons with nonprogressive pulmonary tuberculosis has ranged from 18 to 84%. In addition to all of the factors mentioned previously, the dose of isoniazid utilized, the duration and regularity with which it is taken (compliance), and the prevalence of isoniazid resistant organisms in the population would be expected to influence the magnitude of this protective effect. In spite of the complexities of the issues discussed herein, the practical management of these patients in most cases is relatively simple. The risk of progressive tuberculosis among patients with positive tuberculin tests, negative cultures, and abnormal chest X ray films consistent with nonprogressive pulmonary tuberculosis is sufficiently high to justify the use of preventive therapy, unless one or both of the following situations exist: the individual has already received an adequate and appropriate course of chemotherapy (either prior therapy for disease or a prior course of preventive therapy); or there is a contraindication to the use of isoniazid. If other factors are present that add to the risk, they make the use of preventive therapy more imperative, but they do not alter this basic approach.