Opportunities and problems in the study of chronic disease in industry

1. 1. Whether the potential value of the pre-employment and periodic physical examination in adding to knowledge of chronic disease can be realized is dependent upon whether the observations made on the individual employee are, or can be, recorded and organized in such a way as to (a) delineate the dimensions of the problem among employees as a group and (b) identify the factors influencing the size of the problem. 2. 2. The purpose of this paper has been to examine the feasibility of achieving these objectives with data available from the employment and periodic physical examinations of employees of the E. I. duPont de Nemours Company. 3. 3. The prevalence of high blood pressure, skin diseases, respiratory diseases, heart disease, arthritis, diabetes, cancer, and diseases of the blood and blood-making organs was examined among employees in the different plants of the Company. 4. 4. The most striking feature of the prevalence was the tremendous amount of variation found in the rates for different plants. This variation was not confined to specific diagnoses. There was also great variation in the frequency with which any diagnoses were made. 5. 5. In addition to great variations in prevalence of chronic diseases among the plants at a particular time, there were also wide variations over a period of time in the apparent prevalence of certain conditions in the group of plants. 6. 6. Two broad hypotheses to explain this variation are suggested: (a) that the observed variation in prevalence is real or (b) that it is the result of differences in examining procedures or other techniques. There is a suggestion in the data that the second of the two hypotheses is the more probable. 7. 7. The conclusion is reached that a more detailed investigation into examining procedures, recording practices, and reporting procedures is warranted. 8. 8. This conclusion has significance for industry generally because (a) similar wide variations were observed among the plants of another major chemical company and (b) the practical uses of knowledge of the extent of particular diseases in industry make it important to know just how widespread this phenomenon of variation is. If it is confined to the chemical industry, the problem is different from that which would be the case if such variation is found in industry generally. One cannot deal with these practical problems without a better understanding of the extent and nature of this variation.