WordNet

an instance of something occurring; "a disease of frequent occurrence"; "the occurrence (or presence) of life on other planets"
be worthy of or have a certain rating; "This bond rates highly"
amount of a charge or payment relative to some basis; "a 10-minute phone call at that rate would cost $5" (同)charge per unit
a magnitude or frequency relative to a time unit; "they traveled at a rate of 55 miles per hour"; "the rate of change was faster than expected"
a quantity or amount or measure considered as a proportion of another quantity or amount or measure; "the literacy rate"; "the retention rate"; "the dropout rate"
assign a rank or rating to; "how would you rank these students?"; "The restaurant is rated highly in the food guide" (同)rank, range, order, grade, place
estimate the value of; "How would you rate his chances to become President?"; "Gold was rated highly among the Romans" (同)value
give (hair) the appearance of being fuller by using a rat
a pad (usually made of hair) worn as part of a womans coiffure
any of various long-tailed rodents similar to but larger than a mouse
catch rats, especially with dogs
desert ones party or group of friends, for example, for ones personal advantage
employ scabs or strike breakers in
the relative frequency of occurrence of something (同)relative incidence
the striking of a light beam on a surface; "he measured the angle of incidence of the reflected light"
standing or position on a scale
a local tax on property (usually used in the plural)

PrepTutorEJDIC

〈U〉(事件などが)『起こること』,発生 / 〈C〉『でき事』,事件
〈C〉『割合』,『率』 / 〈C〉《the~,a~》『速度』(speed),進度 / 〈C〉『値段』,『相場』;料金 / 〈U〉等級(class),(…)等 / 《複数形ぃ》《英》地方税 / (…の金額に)…‘の'『値段を決める』,見積もる《+『名』+『at』+『名』》 / …‘を'『評価する』,みなす / 《米話》…‘に'値する,‘の'価値がある / 『評価される』;みなされる
…‘を'どなりつける
『ネズミ』 / ひきょう者,裏切り者 / ネズミをつかまえる / 《話》(人を)裏切る,密告する《+『on』+『名』〈人〉》
(病気・事件・犯罪などの)発生率,頻度;発生(影響)する範囲 / 投射[角],入射[角]
〈C〉〈U〉（品質・技量などによる）格づけ,評価 / 〈C〉（個人・会社の経済的な）信用度 / 〈C〉(トン・馬力による)(船舶・車)の等級 / 〈C〉(テレビ・ラジオの)視聴率

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/07 10:56:03」(JST)

wiki en

[Wiki en表示]

Play media

Evolution of weekly incidence rates of Dengue fever in Cambodia from January 2002 to December 2008.

Incidence is a measure of the probability of occurrence of a given medical condition in a population within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate^[1] with a denominator.

Incidence proportion (also known as cumulative incidence) is the number of new cases within a specified time period divided by the size of the population initially at risk. For example, if a population initially contains 1,000 non-diseased persons and 28 develop a condition over two years of observation, the incidence proportion is 28 cases per 1,000 persons, i.e. 2.8%.

Incidence rate

The incidence rate is the number of new cases per population at risk in a given time period .^[2] When the denominator is the sum of the person-time of the at risk population, it is also known as the incidence density rate or person-time incidence rate.^[3] In the same example as above, the incidence rate is 14 cases per 1000 person-years, because the incidence proportion (28 per 1,000) is divided by the number of years (two). Using person-time rather than just time handles situations where the amount of observation time differs between people, or when the population at risk varies with time.^[4] Use of this measure implies the assumption that the incidence rate is constant over different periods of time, such that for an incidence rate of 14 per 1000 persons-years, 14 cases would be expected for 1000 persons observed for 1 year or 50 persons observed for 20 years.

When this assumption is substantially violated, such as in describing survival after diagnosis of metastatic cancer, it may be more useful to present incidence data in a plot of cumulative incidence, over time, taking into account loss to follow-up, using a Kaplan-Meier Plot.

Consider the following example. Say you are looking at a sample population of 225 people, and want to determine the incidence rate of developing HIV over a 10-year period. At the beginning of the study (t=0) you find 25 cases of existing HIV. You follow-up at 5 years (t=5 yrs) and find 20 new cases of HIV. You again follow-up at the end of the study (t=10 yrs)and find 30 new cases. If you were to measure prevalence you would simply take the total number of cases (25 + 20 + 30 = 75) and divide by your sample population (225). So prevalence would be 75/225 = 0.33 or 33%. This tells you how widespread HIV is in your sample population, but little about the actual risk of developing HIV. To measure incidence you must take into account how many years each person contributed to the study, and when they developed HIV. When it is not known exactly when a person develops the disease in question, epidemiologists frequently use the actuarial method, and assume it was developed at a half-way point between follow-ups. For example, at 5 yrs you found 20 new cases, so you assume they developed HIV at 2.5 years, thus contributing (20 * 2.5) =50 person-years. At 10 years you found 30 new cases. These people did not have HIV at 5 years, but did at 10, so you assume they were infected at 7.5 years, thus contributing (30 * 7.5)= 225 person-years. That is a total of (225 + 50)= 275 person years so far. You also want to account for the 150 people who never had or developed HIV over the 10-year period, (150 * 10) contributing 1500 person-years. That is a total of (1500 + 275) =1775 person-years. Now take the 50 new cases of HIV, and divide by 1775 to get 0.028, or 28 cases of HIV per 1000 population, per year. In other words, if you were to follow 1000 people for one year, you would see 28 new cases of HIV. This is a much more accurate measure of risk than prevalence.

Incidence vs. prevalence

Incidence should not be confused with prevalence, which is the proportion of cases in the population at a given time rather than rate of occurrence of new cases. Thus, incidence conveys information about the risk of contracting the disease, whereas prevalence indicates how widespread the disease is. Prevalence is the proportion of the total number of cases to the total population and is more a measure of the burden of the disease on society with no regard to time at risk or when subjects may have been exposed to a possible risk factor. Prevalence can also be measured with respect to a specific subgroup of a population (see: denominator data). Incidence is usually more useful than prevalence in understanding the disease etiology: for example, if the incidence rate of a disease in a population increases, then there is a risk factor that promotes the incidence.

For example, consider a disease that takes a long time to cure and was widespread in 2002 but dissipated in 2003. This disease will have both high incidence and high prevalence in 2002, but in 2003 it will have a low incidence yet will continue to have a high prevalence (because it takes a long time to cure, so the fraction of individuals that are affected remains high). In contrast, a disease that has a short duration may have a low prevalence and a high incidence. When the incidence is approximately constant for the duration of the disease, prevalence is approximately the product of disease incidence and average disease duration, so prevalence = incidence × duration. The importance of this equation is in the relation between prevalence and incidence; for example, when the incidence increases, then the prevalence must also increase. Note that this relation does not hold for age-specific prevalence and incidence, where the relation becomes more complicated.^[5]

References

^ "incidence" at Dorland's Medical Dictionary
^ Rothman, Kenneth J., Lash, Timothy L., Greenland, Sander. Modern Epidemiology. ISBN 9780781755641 ISBN 0781755646>"incidence rate" at Dorland's Medical Dictionary
^ Last, John M., ed. (2001). A Dictionary of Epidemiology (4 ed.). New York, NY: Oxford University Press. ISBN 0-19-514169-5.
^ Coggon D, Rose G, Barker DJP (1997). "Quantifying diseases in populations". Epidemiology for the Uninitiated (4th edition ed.). BMJ. ISBN 0-7279-1102-3.
^ Brinks R (2011) "A new method for deriving incidence rates from prevalence data and its application to dementia in Germany", arXiv:1112.2720

External links

Calculation of standardized incidence rate
PAMCOMP Person-Years Analysis and Computation Programme for calculating standardized incidence rates (SIRs)

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 心房細動におけるリズムコントロールと心拍数コントロールの比較 rhythm control versus rate control in atrial fibrillation
2. 関節リウマチの全身および非関節症状の概要 overview of the systemic and nonarticular manifestations of rheumatoid arthritis
3. 突然の心停止および心突然死の概要 overview of sudden cardiac arrest and sudden cardiac death
4. 慢性腎臓病の疫学 epidemiology of chronic kidney disease
5. 心不全患者における心房細動のマネージメント the management of atrial fibrillation in patients with heart failure

English Journal

Incidence of hip fractures in Germany, 1995-2010.

Icks A, Arend W, Becker C, Rapp K, Jungbluth P, Haastert B.SourceDepartment of Public Health, Faculty of Medicine, Heinrich-Heine University Düsseldorf, Moorenstr. 59, 40225 Düsseldorf, Germany. andrea.icks@uni-duesseldorf.de
Archives of osteoporosis.Arch Osteoporos.2013 Dec;8(1-2):140. doi: 10.1007/s11657-013-0140-5. Epub 2013 May 15.
We analyzed hip fracture incidence trends in Germany in 1995-2010, using national hospital discharge register. Overall, after age-sex-region adjustment, there was no significant trend. However, stratified analyses showed a significant decrease in younger people. In the elderly, there was a moderate
PMID 23674147

Does insufficient access to dual-energy X-ray absorptiometry (DXA) stifle the provision of quality osteoporosis care in New Zealand?

Milsom S, Leung W, Twigden V, Mitchell P, Nowitz M, Cornish J.SourceDepartment of Obstetrics and Gynaecology, University of Auckland, Private Bag, Auckland Mail Centre, Auckland, New Zealand.
Archives of osteoporosis.Arch Osteoporos.2013 Dec;8(1-2):120. doi: 10.1007/s11657-013-0120-9. Epub 2013 Jan 30.
Access to dual-energy X-ray absorptiometry (DXA) scanning varies significantly throughout New Zealand with the majority of scans funded privately or through the health industry. Barriers to access need to be addressed if osteoporosis guidelines are to be implemented across the country equitably, to
PMID 23361437

Japanese Journal

Risk Factors for Infection in Patients with Remitted Rheumatic Diseases Treated with Glucocorticoids

Matsumoto Yoshinori,Sada Ken-ei,Takano Mariko,Toyota Noriko,Yamanaka Ryutaro,Sugiyama Koichi,Wakabayashi Hiroshi,Kawabata Tomoko,Otsuka Fumio,Makino Hirofumi
Acta Medica Okayama 65(5), 329-334, 2011-10
… The primary endpoint was the incidence rate of infection during a period from 1 to 2 months after the commencement of treatment. …
NAID 80022078064

Clinical efficacy and safety of micafungin in Japanese patients with chronic pulmonary aspergillosis: a prospective observational study.

Kohno Shigeru,Izumikawa Koichi,Kakeya Hiroshi,Miyazaki Yoshitsugu,Ogawa Kenji,Amitani Ryoichi,Niki Yoshihito,Kurashima Atsuyuki
Medical Mycology : official publication of the International Society for Human and Animal Mycology 49(7), 688-693, 2011-10
… The overall clinical efficacy rate was 68.4% (26/38 patients), which is comparable to the results obtained in clinical trials for marketing approval conducted in Japan. … No relationship between the incidence of adverse drug reactions and age of the patients, MCFG dose, or duration of treatment was observed. …
NAID 120003751852

Related Pictures

★リンクテーブル★

リンク元	「疾患と死亡に関わる疫学指標」「有病率」「罹患率」「occurrence」「出現率」
関連記事	「rate」「incidence」「rat」

「疾患と死亡に関わる疫学指標」

　　[★]

		定義	特徴	式
罹患率	incidence rate	単位人口(暴露人口、危険人口)に対する一定期間内に新たに疾病異常者となった者の割合	動的	一定の観察期間内に新規発生した患者数 [人] / 危険暴露人口一人一人の観察期間の総和 [人年]
有病率	prevalence rate	単位人口に対する一時点における疾病異常者の割合	静的	集団のある一時点における疾病を有する者の数[人] / 集団の調査対象全員の数[人]
死亡率	mortality rate	単位人口に対する一定期間内における死亡数の割合		集団のある一定期間内における死亡者数[人] / 集団の調査対象全員の数[人]
致命率	case fatality rate	一定期間内において、対象とする疾患にかかった者がその疾患で死亡する者の割合	急性疾患の重篤度を表す。	死亡率 / 罹患率
生存率	survival rate	対象とする疾患に罹患しているのものが、一定期間中に死亡から免れる確率	慢性疾患の予後判定に用いられる。	(1-死亡率)の積和