An Evaluation of a Chest X-Ray Resurvey of an Industrial Plant

Abstract

As the mass chest survey movement gains momentum there will undoubtedly be requests for resurveys. The question arises as to the value of this procedure in the tuberculosis control program. The fundamental purpose of a mass chest survey is to discover cases of tuberculosis I not previously known to the health department by examining radiographically various segments of the population. To be of value, therefore, repeat surveys should be directed at those industries and groups in which there is reason to expect, at intervals, a significant number of new or unknown cases of tuberculosis. The selection of such groups will depend upon knowledge of several factors, among which are the interval since the first survey, labor or membership turnover within this period, the racial and economic characteristics of the group, the thoroughness of preplacement examinations, the hazard of silicosis, the incidence of tuberculosis in persons whose X-rays were previously reported as normal, and the completeness of case reporting in the area. Since the relative importance of each of these factors may vary greatly as between different industries and communities, it is clear that at the present time there can be no general rule regarding the frequency of resurveys. Nevertheless, the accumulated experience of many observers will be of value in singling out the population groups for which periodic mass X-ray examinations are indicated. The purpose of the present paper is to report the results of two mass chest X-ray surveys done after an interval of 18 months in a large industrial concern in Cleveland, Ohio. It is hoped that the discussion of the comparative results of these two surveys will throw some light on the following questions: (a) How much tuberculosis may be expected among persons reported to be nontuberculous in the first survey; and of this, how much was missed at the time, and how much apparently developed in the interval between surveys? (b) What was the prevalence of tuberculosis among new employees, i. e., persons hired between surveys?