第07章 相對(duì)數(shù)及其應(yīng)用.ppt

1、,第七章 相對(duì)數(shù)及其應(yīng)用,大連醫(yī)科大學(xué) 劉啟貴,在臨床研究的統(tǒng)計(jì)資料中，除了前述的計(jì)量資料外，還有陰性和陽(yáng)性、有效和無(wú)效、治愈和未治愈、死亡與未死亡及各種疾病的分類(lèi)等。例如某病用A法治療100人，有效80人；B法治療 150人，有效100人。若僅用絕對(duì)數(shù)80人和 100人比較會(huì)得到B法比A法好的錯(cuò)誤結(jié)論。 在比較兩法的療效，使計(jì)數(shù)資料具有可比性，將原始的兩個(gè)資料（絕對(duì)數(shù)）之比所得指標(biāo)統(tǒng)稱(chēng)為相對(duì)數(shù)（relative number）。,為什么引入相對(duì)數(shù),相對(duì)數(shù)概念,率（rate） 構(gòu)成比（constituent ratio） 相對(duì)比（relative ratio）,相對(duì)數(shù)種類(lèi),率,概念：率是表示某

2、種現(xiàn)象發(fā)生的頻率和強(qiáng)度，常以百分率（%）、千分率（）、萬(wàn)分率（/萬(wàn)）、十萬(wàn)分率（10萬(wàn)）等表示 計(jì)算公式： 注意：比例基數(shù)”通常依據(jù)習(xí)慣而定，治愈率、感染率用百分率，出生率、死亡率用千分率，某些疾病的死亡率用十萬(wàn)分率。 各率相互獨(dú)立，其之和不為1（如是則屬巧合）,構(gòu)成比,概念：又稱(chēng)構(gòu)成指標(biāo)，表示事物內(nèi)部各個(gè)組成部分所占整體的比重，通常以100為比例基數(shù)，以百分比表示 計(jì)算公式： 注意：各組成部分的構(gòu)成比之和為100%，某一部分比重增大，則其它部分相應(yīng)減少。,例7.1 某醫(yī)院某月各科室住院病人數(shù)及死亡人數(shù),相對(duì)比,概念：相對(duì)比是兩個(gè)有關(guān)聯(lián)指標(biāo)之比，用以描述兩者的對(duì)比水平，常用R表示。 計(jì)算公式：

3、 注意：A大于B用倍數(shù)表示，A小于B時(shí)用百分?jǐn)?shù)表示,相對(duì)比的種類(lèi),1.兩類(lèi)個(gè)體例數(shù)之比 如我國(guó)1982年人口普查的男性人口數(shù)為519433369，女性人口數(shù)為488741919人，求人口數(shù)的男女比例。 R = 519433369488741919 = 1.063 人口數(shù)的男女比為1.063:1。,相對(duì)比的種類(lèi),2.兩個(gè)率之比 某地某年齡組男性吸煙和非吸煙的冠心病死亡資料下表所示,試分析其相對(duì)危害度。,RR = 240.5112.4 = 2.139 說(shuō)明男性吸煙的冠心病死亡率是不吸煙的死亡率的2.139倍。這種指標(biāo)在流行病學(xué)研究中稱(chēng)為相對(duì)危險(xiǎn)度(relative risk簡(jiǎn)寫(xiě)為RR )。,相對(duì)比

4、的種類(lèi),3.兩個(gè)相對(duì)比之比 臨床醫(yī)生欲探索某病的病因，在以醫(yī)院病例為基礎(chǔ)作病例對(duì)照研究時(shí)，一般不能計(jì)算出RR，但可以計(jì)算出疾病組暴露比數(shù)與對(duì)照組暴露比數(shù)之比，稱(chēng)之為比數(shù)比或優(yōu)勢(shì)比（odds ratio簡(jiǎn)寫(xiě)為OR） 服用反應(yīng)停與肢體缺陷關(guān)系病例對(duì)照研究,本例,相對(duì)數(shù)使用應(yīng)注意的問(wèn)題,不要把構(gòu)成比與率相混淆 使用相對(duì)數(shù)時(shí)，分母不宜過(guò)小 要注意資料的可比性 要注意使用率的標(biāo)準(zhǔn)化 比較兩個(gè)樣本率或構(gòu)成比時(shí)，應(yīng)考慮存在抽樣誤差，對(duì)于樣本之間的差異應(yīng)作統(tǒng)計(jì)學(xué)檢驗(yàn),率的標(biāo)準(zhǔn)化,率的標(biāo)準(zhǔn)化,率的標(biāo)準(zhǔn)化（standardization）是為了在比較兩個(gè)不同人群的患病率、發(fā)病率、死亡率等資料時(shí)，消除其內(nèi)部構(gòu)成（如

5、年齡、性別、工齡、病程長(zhǎng)短等）的影響。如年齡會(huì)影響死亡率，年齡越大，死亡率可能越大；病情越重，越難治愈，治愈率就越低。,將上表資料中的兩組同病型的人數(shù)之和作為標(biāo)準(zhǔn)構(gòu)成 ，計(jì)算如下：,西醫(yī)療法組標(biāo)準(zhǔn)化后的總治愈率為： 中西醫(yī)結(jié)合療法組標(biāo)準(zhǔn)化后的總治愈率為： 可見(jiàn)，中西醫(yī)結(jié)合療法組標(biāo)化后的總治愈率高于西醫(yī)療法組標(biāo)化后的總治愈率。,醫(yī)學(xué)常用相對(duì)數(shù),Incidence (Rate),Incidence is the number of cases of disease having their onset during a prescribed period of time. It is often

6、expressed as a rate (for example, the incidence of measles per 1,000 children 5-15 years of age during a specified year). Incidence is a measure of morbidity or other events that occur within a specified period of time.,Incidence (Rate)發(fā)病率,Prevalence (Rate),Prevalence is the number of cases of a dis

7、ease, infected persons, or persons with some other attribute present during a particular interval of time. It is often expressed as a rate (for example, the prevalence of diabetes per 1,000 persons during a year).,Prevalence (Rate)患病率,Death Rate死亡率,A death rate is calculated by dividing the number o

8、f deaths in a population in a year by the midyear resident population. 死亡率(又稱(chēng)粗死亡率)指在一定時(shí)期內(nèi)(通常為一年)一定地區(qū)的死亡人數(shù)與同期平均人數(shù)(或期中人數(shù))之比，一般用千分率表示。計(jì)算公式為：,Case-Fatality (Rate)病死率,Case-fatality (rate) is a measure of the severity of a disease and is defined as the proportion of cases of a specified disease or conditi

9、on which are fatal within a specified time.,Proportion Dying of a Specific Cause死因構(gòu)成,Deaths of a specific cause expressed as a percentage of all deaths Number of deaths in a group / Total Deaths,Case-Fatality (Rate)病死率,Age-Specific Death Rate年齡別死亡率,Number of deaths for a specified age group per 1,00

10、0 population in the same age group. (Deaths for Specified Age Group / Population for Same Specified Age Group) x 1000,Cause-Specific Death Rate死因別死亡率,Number of deaths due to a specific cause per 100,000 population. (Deaths Due to a Specified Cause / Total Population) x 100000,Infant Mortality Rate嬰兒

11、死亡率,An infant mortality rate is based on period files calculated by dividing the number of infant deaths during a calendar year by the number of live births reported in the same year. It is expressed as the number of infant deaths per 1,000 live births.,Under-Five Mortality Rate 5歲以下兒童死亡率,The Under-

12、Five Mortality Rate is the number of children who have died between birth and their fifth birthday expressed per thousand live births.,Maternal Mortality Rate孕產(chǎn)婦死亡率,Maternal Mortality Rate is defined as the number of maternal deaths per 100,000 live births. The maternal mortality rate is a measure o

13、f the likelihood that a pregnant woman will die from maternal causes. The number of live births used in the denominator is a proxy for the population of pregnant women who are at risk of a maternal death.,Maternal Death,The death of woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated b