Case fatality rate
In epidemiology, case fatality rate (CFR) – or sometimes more accurately case-fatality risk – is the proportion of people who have been diagnosed with a certain disease and end up dying of it. Unlike a disease's mortality rate, the CFR does not take into account the time period between disease onset and death. A CFR is generally expressed as a percentage. It is a measure of disease lethality, and thus may change with different treatments.[1] CFRs are most often used for with discrete, limited-time courses, such as acute infections.
Terminology
The mortality rate – often confused with the CFR – is a measure of the relative number of deaths (either in general, or due to a specific cause) within the entire population per unit of time.[2] A CFR, in contrast, is the number of deaths among the number of diagnosed cases only, regardless of time or total population.[3]
From a mathematical point of view, by taking values between 0 and 1 or 0% and 100%, CFRs are actually a measure of
Sometimes the term case fatality ratio is used interchangeably with case fatality rate, but they are not the same. A case fatality ratio is a comparison between two different case fatality rates, expressed as a ratio. It is used to compare the severity of different diseases or to assess the impact of interventions.[6]
Because the CFR is not an
Example calculation
If 100 people in a community are diagnosed with the same disease, and 9 of them subsequently die from the effects of the disease, the CFR would be 9%. If some of the cases have not yet resolved (neither died nor fully recovered) at the time of analysis, a later analysis might take into account additional deaths and arrive at a higher estimate of the CFR, if the unresolved cases were included as recovered in the earlier analysis. Alternatively, it might later be established that a higher number of people were subclinically infected with the pathogen, resulting in an IFR below the CFR.[citation needed]
A CFR may only be calculated from cases that have been resolved through either death or recovery. The preliminary CFR, for example, of a newly occurring disease with a high daily increase and long resolution time would be substantially lower than the final CFR, if unresolved cases were not excluded from the calculation, but added to the denominator only.
Infection fatality rate
Like the case fatality rate, the term infection fatality rate (IFR) also applies to
Examples
Some examples will suggest the range of possible CFRs for diseases in the real world:
- The CFR for the
- As of 24 Apr 2024,
- The CFR for yellow fever is about 5-6% (but 40-50% in severe cases).[17][18][19]
- Legionnaires' disease has a CFR of about 15%.[20]: 665
- Left untreated,
- Active tuberculosis, the infection with the highest mortality rate, has a CFR of 43% in the absence of HIV.[24][25]
- Ebola virus disease, one of the infections with the highest lethality, has a CFR as high as 90%.[26]
- Naegleriasis (also known as primary amoebic meningoencephalitis), has a CFR greater than 95%, with a few of the survivors having been treated with heroic doses of amphotericin B and other off-label drugs.[citation needed]
- Rabies has a CFR greater than 99% in unvaccinated individuals.[27] A few people have survived either by being vaccinated (but after symptoms started, or else later than ideal), or more recently, by being put into a medically induced coma.[citation needed]
See also
- List of human disease case fatality rates
- Mortality rate – Deaths per 1000 individuals per year
- Pandemic severity index – Proposed measure of the severity of influenza
References
- ^ Rebecca A. Harrington, Case fatality rate at the Encyclopædia Britannica
- ^ For example, a diabetes mortality rate of 5 per 1,000 or 500 per 100,000 characterizes the observation of 50 deaths due to diabetes in a population of 10,000 in a given year, resulting in a yearly diabetes mortality rate of 0.5%, far below the actual diabetic individual's fatality risk. (See Harrington, Op. cit..)
- ^ "Coronavirus: novel coronavirus (COVID-19) infection" (PDF). Elsevier. 2020-03-25. Archived from the original (PDF) on 2020-03-27. Retrieved 2020-03-27.
- ISBN 0-19-514168-7
- ISBN 0-316-35636-0
- ECDC. Archivedfrom the original on 2020-03-25. Retrieved 2020-03-25.
- ^ Peter Cummings: Analysis of Incidence Rates. In: CRC Press (2019).
- ^ a b "Estimating mortality from COVID-19". www.who.int. Retrieved 2021-12-13.
- ^ "Infection fatality rate". DocCheck Medical Services GmbH. Retrieved 25 March 2020.
- ^ "Global Covid-19 Case Fatality Rates". Centre for Evidence-Based Medicine. Retrieved 25 March 2020.
- ^ "Report of the Review Committee on the Functioning of the International Health Regulations (2005) in relation to Pandemic (H1N1) 2009" (PDF). 2011-05-05. p. 37. Archived (PDF) from the original on 14 May 2015. Retrieved 1 March 2015.
- PMID 16494711. Archived from the originalon 2009-10-06. Retrieved 2009-04-17.
- S2CID 34200426. Retrieved 2009-04-29.
- ^ Ritchie, Hannah; Mathieu, Edouard; Rodés-Guirao, Lucas; Appel, Cameron; Giattino, Charlie; Ortiz-Ospina, Esteban; Hasell, Joe; Macdonald, Bobbie; Beltekian, Diana; Dattani, Saloni; Roser, Max (2020–2022). "Coronavirus Pandemic (COVID-19)". Our World in Data. Retrieved 2024-04-24.
- PMID 15018127.
- ^ "MERS situation update, January 2020". World Health Organization - Regional Office for the Eastern Mediterranean.
- ^ "Yellow fever". Fact sheets. World Health Organization. 7 May 2019.
- PMID 24980556– via Oxford University Press.
- S2CID 237056056.
- ISBN 978-0-87553-189-2.
- ISBN 9780160900150. Archived from the original(PDF) on 2015-02-09. Retrieved 2021-11-25.
- ^ "Antibiotics for treating plague: A systematic review (Executive summary)". WHO guidelines for plague management: revised recommendations for the use of rapid diagnostic tests, fluoroquinolones for case management and personal protective equipment for prevention of post-mortem transmission [Internet]. World Health Organization. 2021.
- S2CID 208790222– via PubMed.
- S2CID 1541253.
- PMID 21483732.
- ^ King, John W (April 2, 2008). "Ebola Virus". eMedicine. WebMd. Retrieved 2008-10-06.
- ^ "Rabies Fact Sheet N°99". World Health Organization. July 2013. Retrieved 28 February 2014.