Risks and Rates - Revision history

Bosmana fem at 21:13, 22 March 2023

2023-03-22T21:13:50Z

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	* Aileen Kitching		* Aileen Kitching
	* Sabrina Bacci		* Sabrina Bacci


			[[Category:Measures of Disease Occurrence]]

Bosmana fem at 18:02, 19 December 2022

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 Incidence rates are a subset of rates in which we are interested in quantifying new events ("new cases" of disease)
-The term rate is sometimes used incorrectly in epidemiology. For example to replace the term risk (as in attack rates and case fatality rates).
+The term rate is sometimes used incorrectly in epidemiology. For example, to replace the term risk (as in attack rates and case fatality rates).
-References
+=References=
 <references/>

Bosmana fem at 18:00, 19 December 2022

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	In a population, the risk of a disease measures the proportion of people that develops this disease between two specified points in time (T0 and T1). It is calculated as the number of persons developing the disease during the observation period divided by the number of persons present at the beginning of the observation period. The denominator represents the population at risk of developing the disease at the beginning of the observation period. The time spent by each individual in the observation period is not considered.		In a population, the risk of a disease measures the proportion of people that develops this disease between two specified points in time (T0 and T1). It is calculated as the number of persons developing the disease during the observation period divided by the number of persons present at the beginning of the observation period. The denominator represents the population at risk of developing the disease at the beginning of the observation period. The time spent by each individual in the observation period is not considered.


	[[File:0272.risk.png-550x0.png\|400px\|frameless\|left]]		[[File:0272.risk.png-550x0.png\|400px\|frameless\|left]]



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	Rates		Rates
	Rates are a measure of the occurrence of a phenomenon <ref>Porta, M. A Dictionary of Epidemiology, Fifth edition. Oxford University press, 2008.</ref>. A rate is calculated as the number of events that have occurred, divided by the total time experienced by the population under observation, usually expressed in person-years. Rates are usually multiplied by a power of 10 to convert the rate into a decimal or whole number, which is easy to interpret.		Rates are a measure of the occurrence of a phenomenon <ref>Porta, M. A Dictionary of Epidemiology, Fifth edition. Oxford University press, 2008.</ref>. A rate is calculated as the number of events that have occurred, divided by the total time experienced by the population under observation, usually expressed in person-years. Rates are usually multiplied by a power of 10 to convert the rate into a decimal or whole number, which is easy to interpret.


	[[File:1212.rate.png-550x0.png\|400px\|frameless\|left]]		[[File:1212.rate.png-550x0.png\|400px\|frameless\|left]]

Bosmana fem at 17:59, 19 December 2022

2022-12-19T17:59:45Z

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	[[File:0272.risk.png-550x0.png\|400px\|frameless\|left]]		[[File:0272.risk.png-550x0.png\|400px\|frameless\|left]]





	A risk is a probability. It will range from 0 to 1, or 0% to 100% if expressed as a percentage. The risk of disease is therefore also called incidence proportion.		A risk is a probability. It will range from 0 to 1, or 0% to 100% if expressed as a percentage. The risk of disease is therefore also called incidence proportion.
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	Rates		Rates
	Rates are a measure of the occurrence of a phenomenon <ref>Porta, M. A Dictionary of Epidemiology, Fifth edition. Oxford University press, 2008.</ref>. A rate is calculated as the number of events that have occurred, divided by the total time experienced by the population under observation, usually expressed in person-years. Rates are usually multiplied by a power of 10 to convert the rate into a decimal or whole number, which is easy to interpret.		Rates are a measure of the occurrence of a phenomenon <ref>Porta, M. A Dictionary of Epidemiology, Fifth edition. Oxford University press, 2008.</ref>. A rate is calculated as the number of events that have occurred, divided by the total time experienced by the population under observation, usually expressed in person-years. Rates are usually multiplied by a power of 10 to convert the rate into a decimal or whole number, which is easy to interpret.

			[[File:1212.rate.png-550x0.png\|400px\|frameless\|left]]





	~~[[File:1212.rate.png-550x0.png\|400px\|frameless\|left]]~~

	In a study, it is possible that each person experiences the same event more than one time.		In a study, it is possible that each person experiences the same event more than one time.

Bosmana fem at 17:57, 19 December 2022

2022-12-19T17:57:49Z

← Older revision		Revision as of 17:57, 19 December 2022
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	In a population, the risk of a disease measures the proportion of people that develops this disease between two specified points in time (T0 and T1). It is calculated as the number of persons developing the disease during the observation period divided by the number of persons present at the beginning of the observation period. The denominator represents the population at risk of developing the disease at the beginning of the observation period. The time spent by each individual in the observation period is not considered.		In a population, the risk of a disease measures the proportion of people that develops this disease between two specified points in time (T0 and T1). It is calculated as the number of persons developing the disease during the observation period divided by the number of persons present at the beginning of the observation period. The denominator represents the population at risk of developing the disease at the beginning of the observation period. The time spent by each individual in the observation period is not considered.

			[[File:0272.risk.png-550x0.png\|400px\|frameless\|left]]

	A risk is a probability. It will range from 0 to 1, or 0% to 100% if expressed as a percentage. The risk of disease is therefore also called incidence proportion.		A risk is a probability. It will range from 0 to 1, or 0% to 100% if expressed as a percentage. The risk of disease is therefore also called incidence proportion.
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			[[File:1212.rate.png-550x0.png\|400px\|frameless\|left]]

	In a study, it is possible that each person experiences the same event more than one time.		In a study, it is possible that each person experiences the same event more than one time.

Bosmana fem: Created page with "Risks( synonyms: incidence proportion, attack rate) are expressed as percentages. In a population, the risk of a disease measures the proportion of people that develops this..."

2022-12-19T17:19:35Z

Created page with "Risks( synonyms: incidence proportion, attack rate) are expressed as percentages. In a population, the risk of a disease measures the proportion of people that develops this..."

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Risks( synonyms: incidence proportion, attack rate) are expressed as percentages.

In a population, the risk of a disease measures the proportion of people that develops this disease between two specified points in time (T0 and T1). It is calculated as the number of persons developing the disease during the observation period divided by the number of persons present at the beginning of the observation period. The denominator represents the population at risk of developing the disease at the beginning of the observation period. The time spent by each individual in the observation period is not considered.

A risk is a probability. It will range from 0 to 1, or 0% to 100% if expressed as a percentage. The risk of disease is therefore also called incidence proportion.

An example in which 50 out of 200 nursing home residents developed gastroenteritis between 12 and 20 May 2005, the risk of gastroenteritis is 50/200 = 0.25 or 25%.

In intervention-epidemiology, risk is used for short follow-up periods, like outbreaks during which all individuals are assumed to be followed for the same period.

In outbreaks, the term risk is frequently replaced by attack rate, which is also expressed as a percentage. Even though widely accepted in the epidemiological community, the term “attack rate” is technically incorrect, as an attack rate is not a rate but a risk. In outbreaks, a food-specific attack rate measures how many people who ate a certain type of food (or had another exposure) became ill (else "were attacked by that food").

The measurement of risk shows the probability of developing an illness during a specific period of time. However, without knowledge of the time period, it is impossible to interpret a risk <ref>Rothman KJ; Epidemiology: an introduction. Oxford University Press 2002, p.24-28.</ref>. A risk of death of 2% will imply different meanings if it expresses the risk of death during one month, one year, or a 30-year follow-up.

Rates
Rates are a measure of the occurrence of a phenomenon <ref>Porta, M. A Dictionary of Epidemiology, Fifth edition. Oxford University press, 2008.</ref>. A rate is calculated as the number of events that have occurred, divided by the total time experienced by the population under observation, usually expressed in person-years. Rates are usually multiplied by a power of 10 to convert the rate into a decimal or whole number, which is easy to interpret.

In a study, it is possible that each person experiences the same event more than one time.

Incidence rates are a subset of rates in which we are interested in quantifying new events ("new cases" of disease)

The term rate is sometimes used incorrectly in epidemiology. For example to replace the term risk (as in attack rates and case fatality rates).

References
<references/>