The purpose of this book is to introduce the principles and methods of epidemiology defined as the study of the distribution and determinants of disease frequency in man. Since epidemiology has the practical purpose of discovering relations which offer possibilities for disease prevention the search for causal associations is predominant in epidemiology. The strategy of an epidemiological study includes the assembly of all the facts the forming and testing of hypotheses and the choice of the type of study (case-control cohort prospective retrospective cross-sectional or longitudinal study). Disease classification is an essential procedure and it includes 2 components: 1) the grouping of ill persons into categories such that the characteristics of the members of 1 category permit them to be distinguished from the members of another and 2) the arrangement of the disease entities themselves into groups having common characteristics. Measures of disease frequency are incidence attack rate and prevalence; sources of data are vital records and morbidity surveys. Characteristics of the people include age sex race religion marital status migration status occupation and socioeconomic status. Variations in the frequency of different disease manifestations from place to place are of paramount importance as are the changes associated with the passage of time. Awareness of the interactions between person place and time in the causation of disease is extremely important at all times. Cohort studies are especially important; the group or groups to be studied are defined in terms of characteristics manifest prior to the appearance of the disease and are observed over a period of time to determine the frequency of the disease. Case-control studies inquire which groups of individuals have or have not the disease which is under investigation; intervention studies are those designed and carried out specifically as studies of procedures or programs considered to have possibilities for disease prevention. Human genetics and epidemiology interact continually as for example in the study of environmental disease or of familial disease.
Stored only when both papers are in the corpus — 1,472 citations exist upstream.