AN EPIDEMIOLOGIC STUDY OF BLOOD PRESSURE LEVELS IN A BIRACIAL COMMUNITY IN THE SOUTHERN UNITED STATES

A recent symposium on the epidemiology of hypertension (1) may well prove to be of great importance in the understanding of this disorder, not so much for the considerable body of in1 From the Tuberculosis Program, U. S. Public Health Service, Department of Health, Education and Welfare, Washington, D. C. 2 This study was made possible by the facilities of the Museogee County Tuberculosis Study, an enterprise supported by the Georgia State Department, Museogee County Health Department, and the United States Public Health Service. It is an abridgement of a thesis submitted by the author to the School of Hygiene and Public Health, The Johns Hopkins University, in partial fulfillment of the requirements for the degree of Doctor of Public Health. 3 The author acknowledges with gratitude the very considerable assistance given by the entire staff of the Museogee County Tuberculosis Study. He is especially indebted to the following individuals for assistance with particular phases of the study and analysis: Miss Olga Michaelson for the general supervision of the field study; Dr. Carroll E. Palmer, Tuberculosis Program, U. S. Public Health Service, for encouragement and suggestions for the general plan of the study; Adjutant General's Office, U. S. Army, for assistance in tracing members of the sample population who had been stationed at Ft. Benning; Dr. Philip E. Sartwell, School of Hygiene and Public Health, The Johns Hopkins University, for suggestions and assistance with the analysis and presentation of the findings of the study; Prof. William G. Cochran, School of Hygiene and Public Health, The Johns Hopkins University, for general statistical guidance and for the analysis of variance of the regression coefficients of diastolic on systolic blood pressure by race, sex and age. formation made available therein, but more for the deficiencies in present knowledge which were disclosed. These deficiencies were excellently summarized by Clark and Morsell (2) as follows: "(1) There are no consistent standards for blood pressure measurement; (2) there are no established criteria for defining hypertension; (3) none of the existing studies is based on a scientific sample of the population of the country or any subdivision of it; and (4) although the various studies leave no doubt that hypertension is a health problem of great magnitude which varies according to age, sex and race, they do not answer the question as to the actual extent of this problem." Although it is perfectly proper to refer to the epidemiology of hypertension, it should be realized that there are serious difficulties in this approach, largely due to the unfortunate fact that there is no general agreement on a definition of hypertension or hypertensive disease. Yet it is accepted that the first step in an epidemiologic investigation is the definition of terms, including a decision as to who is to be counted as a case (3). The use of a very stringent definition would produce general agreement regarding the cases so identified, but would probably ignore many persons with milder degrees of hypertension. This state of affairs is analagous to the study of poliomyelitis when only patients with paralysis could be identified as cases. If the definition is extended