Group X-ray Surveys in Apparently Healthy Individuals

THE basis of effective tuberculosis control is a sound case-finding program. Such a program must meet certain fundamental requirements. First and foremost, it must result in the discovery of an increasing proportion of the estimated number of cases of tuberculosis in the community. Second, it must lead to the finding of the majority of these cases in the minimal stage of disease. If this latter aspect of the program is not realized, the effectiveness of the treatment facilities of the community, as Drolet (1) has so strikingly shown, will be sharply limited. Not only are we unable to cure a large proportion of the advanced cases of tuberculosis, but we cannot protect society from them, for, at the time they are first discovered, they have already disseminated their disease. The Bureau of Tuberculosis of the Department of Health, of New York City, has always accepted a case-finding program with these dual objectives as its primary responsibility. Until recently, we, in common with other similar organizations, faced this problem solely in the traditional manner. We set up a city-wide system of district clinics, which examined a steadily increasing number of individuals annually. These facilities were confined to the study of those persons referred to us because of a history of contact with tuberculosis or symptoms suggestive of the disease. Every requirement for the adequate investigation of these cases has been met. Each clinic has been staffed by trained chest specialists. X-ray and sputum examinations have been made available to all of our units. A routine calling for the use of these diagnostic aids in every patient over 15 years of age and the graded tuberculin testing of every child under the age of 15, with x-ray examination of all positive reactors, has been in effect. Our generalized district nursing service has been trained to refer all suitable individuals to us, and private physicians have been encouraged to use our facilities for their patients freely. All contacts have been periodically re-examined and re-x-rayed. Through these efforts, in 1937, we examined more than 45,000 individuals and made over 70,000 chest x-ray films in our regular clinics. Yet we failed to satisfy our second criterion for sound case finding, as less than half of the new cases of tuberculosis were discovered in the minimal stage of the disease. It has become steadily more apparent that the failure to find early cases lay in the method, and not in its execution. Examination of contacts and suspects was not enough. Cases discovered in this group were more apt to be in the advanced than the minimal stage of the disease. If early tuberculosis were to be found, we must look for it among those without history or symptoms—the apparently healthy population. In 1933, the opportunity for a study of this type first presented itself.