Epidemiology, Prevalence and Incidence
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Epidemiology[edit | edit source]
It is the study of how often diseases occur in different groups of people and why, and is used to plan and evaluate strategies to prevent illness and as a guide to the management of patients in whom disease has already developed.[1] Epidemiology is often described as the basic science of public health.[2]
Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems[3]
The CDC[2] break this definition down into the important principles of epidemiology:
Study - a scientific discipline with sound methods of scientific inquiry at its foundation. Various methods can be used to carry out epidemiological investigations: surveillance and descriptive studies can be used to study distribution; analytical studies are used to study determinants.[4]
Distribution - the frequency (number of health events in a population and it's relationship of that number to the size of the population) and pattern (the occurrence of health-related events by time, place, and person) of health events in a population.
Determinants - the causes and other factors that influence the occurrence of disease and other health-related events.
Health-related states or events - these may include communicable and non-communicable diseases, chronic diseases, injuries, birth defects, maternal-child health, occupational health, and environmental health. More recently studies have included behaviours related to health and well-being and genetic markers of disease risk.
Specified populations - the epidemiologist is concerned about the collective health of the people in a community or population[2]. A key feature of epidemiology is the measurement of disease outcomes in relation to a population at risk.[1] Implicit in any epidemiological investigation is the notion of a target population about which conclusions are to be drawn and ore often observations can only be made on a study sample, which is selected in some way from the target population.[1]
Application - Epidemiology is not just “the study of” health in a population; it also involves applying the knowledge gained by the studies to community-based practice.
Epidemiology is the study (scientific, systematic, data-driven) of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations (patient is community, individuals viewed collectively), and the application of (since epidemiology is a discipline within public health) this study to the control of health problems.[2]
Prevalence[edit | edit source]
Prevalence (or prevalence proportion and sometimes point prevalence) gives a figure for a factor at a single point in time.[5] This is the prevalenceThe important words are at that point in time because prevalence can tell us only what is happening at a certain point.
Incidence[edit | edit source]
Incidence is the number of instances of illness commencing, or of persons becoming ill (or dying or injured) during a given period in a specified population.[3]
Incidence can tell us how many new cases of a particular illness have been suffered by a community, or it might tell us how patterns of a condition within a population change over time.[5] Incidence is usually expressed as a rate, something that is measured within a set number of people and in a time period.
References[edit | edit source]
- ↑ 1.0 1.1 1.2 The BMJ. What is Epidemiology. Chapter 1 in: Epidemiology for the uninitiated. http://www.bmj.com/about-bmj/resources-readers/publications/epidemiology-uninitiated/1-what-epidemiology (accessed 28 August 2017)
- ↑ 2.0 2.1 2.2 2.3 Introduction to Epidemiology. Lesson 1 in: Centers for Disease Control and Prevention. Principles of Epidemiology in Public Health Practice, An Introduction to Applied Epidemiology and Biostatistics. https://www.cdc.gov/OPHSS/CSELS/DSEPD/SS1978/Lesson1/Section1.html (accessed 28 August 2017)
- ↑ 3.0 3.1 Last JM, editor. Dictionary of epidemiology. 4th ed. New York: Oxford University Press; 2001.
- ↑ World Health Organisation. Epidemiology. http://www.who.int/topics/epidemiology/en/ (accessed 28 August 2017)
- ↑ 5.0 5.1 Shields L, Twycross A. The difference between incidence and prevalence. Paediatric nursing. 2003 Sep 1;15(7):50.
