Public health, epidemiology and health services

Public health and the wider aspects of health administration are connected by their common dependence on the methods of epidemiology. Epidemiology is defined herein as the discipline of occurrence research in medicine. As such, it represents a body of methods rather than knowledge, and is as much applicable to study of the occurrence of phenomena relevant to health services as to phenomena relevant to disease aetiology and prevention. In consequence, much of the information base necessary to the development of health policy is obtained by the use of epidemiological methods. Health services planning and program development depend on an understanding of the relationship between services and the population that they serve, an understanding which is provided by the application of epidemiological concepts. The ongoing delivery of programs in a manner which optimises the use of health resources depends on the ability to respond to changes in the health services environment. Recognition of the changes demanding a response depends on continuing surveillance of the "environment" by use of epidemiological techniques. Finally, the evaluation of health programs against their objectives depends to a substantial degree on the use of epidemiological methods. The discipline of epidemiology arose in public health, but it now belongs to the whole of the health system.