Prevalence

The prevalence (from the Latin praevalēre , 'to be very strong') is an indicator of the incidence of disease in epidemiology and medical statistics . It states what proportion of people or animals in a certain group ( population ) of a defined size is sick with a certain disease or has a risk factor at a certain point in time . As a rule, the prevalence of a disease or disorder in a population is only estimated on the basis of a random sample, since complete testing of a population would be too costly or impossible.

Prevalence vs. Incidence

→ Main article : Incidence (epidemiology)

${\displaystyle {\text{Prävalenz}}={\frac {\text{Anzahl der zum Untersuchungszeitpunkt Kranken}}{\text{Anzahl der in die Untersuchung einbezogenen Individuen}}}}$.

Another measure of the incidence of disease is the incidence or incidence rate. It tells you how many people are newly diagnosed in a certain period of time:

${\displaystyle {\text{Inzidenzrate}}={\frac {\text{Anzahl der neu Erkrankten}}{{\text{betrachtete Zeitspanne}}\times {\text{Anzahl der in die Untersuchung einbezogenen Individuen}}}}}$

often converted or given as the number of new cases per year per 100,000 inhabitants.

In contrast to the incidence, which counts the newly infected patients in the period under review, the prevalence takes into account the total number of all sick people at the time of the examination, regardless of when they were sick. So while the incidence looks at a period of time, the prevalence is a snapshot.

Point prevalence vs. Period prevalence

Unless otherwise stated, prevalence refers to a specific point in time or “on a given reference date”; therefore one also says point prevalence (also reference date prevalence ). This is not always practical, for example in the case of very short, rapidly spreading and regressing illnesses such as the flu, what interests you more is how many people were sick during a week or during the entire flu season.

The period prevalence (also route prevalence ) is determined by a period such as “in the last seven days”, “in sexually mature age” or “in senium ”, in the last year (annual prevalence) or throughout life (lifetime prevalence).

Significance of prevalence information based on the example of obesity :

If in America the proportion of seriously overweight people (hence "the characteristic, the disease") in the adult population (the "certain population"; with children the problem is again different) from 12.0% in 1991 to 17, 9% rose in 1999, the dynamics of events can be conveyed far better by specifying two point prevalence rates than if one had specified the proportion of overweight people as the period prevalence (between 1991 and 1999). The investigation becomes even more meaningful if it is recognized that this increase occurred independently of gender, of socio-demographic groups and geographical regions of the country, i.e. if the more precise determination of the population examined recognizes the problem as a societal one as a whole.

30-day prevalence vs. 12 month prevalence vs. Lifetime prevalence

The term prevalence is also used for drug use and other risk factors . In addition to the “lifetime prevalence”, the “12-month prevalence” and “30-day prevalence” are common measures for the distribution of a certain drug in a certain population group .

The internationally used term "lifetime prevalence" is somewhat misleading in terms of language, since it does not record the occurrence of the event over the entire lifetime, but only the occurrence in the lifetime that has elapsed up to the time of the survey. The expression "overall lifetime prevalence" was coined for the probability of occurrence over the entire lifespan of the study population. So z. In Austria, for example, the point prevalence of alcoholism in the adult population is estimated at 5% and the “overall lifetime prevalence” at 10%.

Forms of prevalence according to survey

There is also a distinction:

• True prevalence (also known as field prevalence) - prevalence in the population. The population should be examined as completely as possible or estimated using a suitable sample design .
• Treatment Prevalence - Prevalence due to contact with a care or treatment facility.
• Administrative prevalence - prevalence based on routine statistics. A special case is the number of cases from case registers, in which all cases of illness in a region or type of facility are collected. One example is the cancer registry.
• Covert Prevalence - Prevalence of untreated cases. The administrative prevalence and the hidden prevalence together give the true prevalence.

Seroprevalence

The seroprevalence is a measure of the detection of certain immunological parameters in a population at a given time. Often it is about the frequency of the occurrence of antibodies in the blood that indicate a previous or existing infection. Seroprevalence is tested using serological methods.

Prevalence of infection

The degree of spread of an infectious disease in a population at a given point in time is known as infection or infection prevalence .

See also

• Prevalence errors

Web links

Wiktionary: Prevalence  - explanations of meanings, word origins, synonyms, translations

Individual evidence

1. ↑ Leon Gordis: Epidemiology. Verlag im Kilian, Marburg 2001, ISBN 3-932091-63-9 , pp. 37-38.
2. ↑ ^{a b c d e} Dictionary of Psychotherapy . Springer-Verlag, 2010, ISBN 978-3-211-99131-2 , pp. 527 ( limited preview in Google Book search).
3. ↑ Lothar Sachs , Jürgen Hedderich: Applied Statistics: Collection of Methods with R. 8., revised. and additional edition. Springer Spectrum, Berlin / Heidelberg 2018, ISBN 978-3-662-56657-2 , p. 197
4. ↑ Uhl, A .; Bachmayer, S .; Kobrna, U .; Puhm, A .; Springer, A .; Head, N .; Beiglböck, W .; Eisenbach-Stangl, I .; Preinsperger, W .; Musalek, M. (2009): Handbook Alcohol - Austria: Figures, data, facts, trends 2009 , third revised and expanded edition. BMG, Vienna ( PDF file ( Memento of the original from December 22, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ) 
5. ↑ Psychiatry, psychosomatic medicine and psychotherapy . Georg Thieme Verlag, 2004, ISBN 978-3-13-495607-8 , p. 18 ( limited preview in Google Book search).
6. ↑ ^{a b} Clinical Psychology & Psychotherapy (textbook with online materials) . Springer-Verlag, 2011, ISBN 978-3-642-13018-2 , pp. 62 ( limited preview in Google Book search).
7. ^ Epidemiology of physical illnesses and limitations in old age . W. Kohlhammer Verlag, 2008, ISBN 978-3-17-018649-1 , pp. 27 ( limited preview in Google Book search).
8. ↑ Epidemiology of Mental Illnesses in Old Age . W. Kohlhammer Verlag, 2006, ISBN 978-3-17-016835-0 , pp. 32 ( limited preview in Google Book search).
9. ↑ Wolfgang Kiehl: Infection protection and infection epidemiology. Technical terms - definitions - interpretations. Ed .: Robert Koch Institute, Berlin 2015, ISBN 978-3-89606-258-1 , p. 118, keyword seroprevalence
10. ↑ Wolfgang Kiehl: Infection protection and infection epidemiology. Technical terms - definitions - interpretations. Ed .: Robert Koch Institute, Berlin 2015, ISBN 978-3-89606-258-1 , p. 103, keyword prevalence