Epidemiology, Prevalence and Incidence: Difference between revisions

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== Epidemiology ==
== Epidemiology ==
Many definitions have been proposed, but the following definition captures the underlying principles of epidemiology:<blockquote>''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''<ref>Last JM, editor. Dictionary of epidemiology. 4th ed. New York: Oxford University Press; 2001. p. 61.</ref></blockquote>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.<ref name=":0">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#chapters http://www.bmj.com/about-bmj/resources-readers/publications/epidemiology-uninitiated/1-what-epidemiology] (accessed 28 August 2017)</ref>  Epidemiology is often described as the basic science of public health<ref name=":1">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#_ref1 https://www.cdc.gov/OPHSS/CSELS/DSEPD/SS1978/Lesson1/Section1.html] (accessed 28 August 2017)
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.<ref name=":0">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#chapters http://www.bmj.com/about-bmj/resources-readers/publications/epidemiology-uninitiated/1-what-epidemiology] (accessed 28 August 2017)</ref>  Epidemiology is often described as the basic science of public health.<ref name=":1">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#_ref1 https://www.cdc.gov/OPHSS/CSELS/DSEPD/SS1978/Lesson1/Section1.html] (accessed 28 August 2017)
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</ref><blockquote>''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''<ref name=":2">Last JM, editor. Dictionary of epidemiology. 4th ed. New York: Oxford University Press; 2001.</ref></blockquote>The CDC<ref name=":1" /> break this definition down into the important principles of epidemiology:
 
The CDC<ref name=":1" /> 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.<ref>World Health Organisation. Epidemiology. http://www.who.int/topics/epidemiology/en/ (accessed 28 August 2017)</ref>  
'''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.<ref>World Health Organisation. Epidemiology. http://www.who.int/topics/epidemiology/en/ (accessed 28 August 2017)</ref>  
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== Prevalence ==
== Prevalence ==
Prevalence (or prevalence proportion and sometimes point prevalence) gives a figure for a factor at a single point in time.<ref name=":3">Shields L, Twycross A. [http://journals.rcni.com/doi/full/10.7748/paed.15.7.50.s31 The difference between incidence and prevalence]. Paediatric nursing. 2003 Sep 1;15(7):50.</ref>  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 ==
== Incidence ==
<blockquote>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.<ref name=":2" /> </blockquote>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.<ref name=":3" />  Incidence is usually expressed as a rate, something that is measured within a set number of people and in a time period.


== References  ==
== References  ==


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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. 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. 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. 3.0 3.1 Last JM, editor. Dictionary of epidemiology. 4th ed. New York: Oxford University Press; 2001.
  4. World Health Organisation. Epidemiology. http://www.who.int/topics/epidemiology/en/ (accessed 28 August 2017)
  5. 5.0 5.1 Shields L, Twycross A. The difference between incidence and prevalence. Paediatric nursing. 2003 Sep 1;15(7):50.