觀察性研究方法設(shè)計(jì)及實(shí)例第四次課

1、Department of Epidemiology & Bio-Statistics觀察性研究方法設(shè)計(jì)及實(shí)例觀察性研究方法設(shè)計(jì)及實(shí)例余運(yùn)賢余運(yùn)賢浙大醫(yī)學(xué)院流行病學(xué)與統(tǒng)計(jì)學(xué)學(xué)科浙大醫(yī)學(xué)院流行病學(xué)與統(tǒng)計(jì)學(xué)學(xué)科Tel：88208191Email： Department of Epidemiology & Bio-StatisticsInduced First-Trimester Abortionand Risk of Mental DisordernAuthor: Munk-Olsen T, Laursen TM, Pedersen CB, Lidegaard , Mortense

2、n PB. nJournal: N Engl J Med. 2011;364(4):332-9. nPublished date: 2011 Jan 27 案例Department of Epidemiology & Bio-Statistics背景和目的背景和目的nBackground： Concern has been expressed about potential harm to womens mental health in association with having an induced abortion (人工流人工流產(chǎn)產(chǎn)), but it remains uncl

3、ear whether induced abortion is associated with an increased risk of subsequent psychiatric problemsnAim: Assess the risk of a first psychiatric contact (精精神癥狀神癥狀) after first-trimester induced abortion, as compared with before the event; we also looked at the risk of a first psychiatric contact aft

4、er, as compared with before, childbirth(分娩分娩).Department of Epidemiology & Bio-Statistics研究設(shè)計(jì)研究設(shè)計(jì)(1) Study PopulationnData from the Danish Civil Registration System (CRS), which holds information on all Danish residents, was used to establish an underlying study population of all girls and women

5、 born in Denmark between 1962 and 1993 who were alive on their 15th birthday, for a total of 954,702 girls and women.nThe CRS was established in 1968, when data were recorded for all people alive and residing in Denmark. nAmong other variables, it includes each residents personal identification numb

6、er (CRS number), which is assigned to all Danes(丹麥人丹麥人) at birth or immigration, sex, date of birth, parents CRS numbers, and daily updated information on vital status. Department of Epidemiology & Bio-Statistics研究設(shè)計(jì)研究設(shè)計(jì)(2)Mental DisordersnThe Danish Psychiatric Central Register covers informati

7、on on mental disorders in the girls and women in our study population and their parents. nThere are no private psychiatric hospitals in Denmark, and the register contains information of inpatient psychiatric contact (ICD-8) from 1969 and information about outpatient psychiatric contact(icd-10)from 1

8、995.nThe girls and women in the study population, as well as their parents, were classified as having a mental disorder if they had records of inpatient or outpatient contact at psychiatric facilities in Denmark for any mental disorder.Department of Epidemiology & Bio-Statistics研究設(shè)計(jì)研究設(shè)計(jì)(3) Induc

9、ed AbortionsnThe Danish National Register of Patients contains data on information on induced abortions of inpatients (from 1977) and outpatients (from 1995) in Denmark, except abortions performed by practicing specialists at private clinic since 2005 or later.nFrom this register, we obtained the da

10、tes of first-trimester medical or surgical induced abortions.nGirls and women with records of induced abortions before January 1, 1995, were excluded from the study to ensure that the sample included only girls and women with a first-ever abortion in the first trimester.nTo further ensure that all i

11、nduced abortions in the study population were first-time abortions, we restricted the population to women and girls born in 1962 or later.Department of Epidemiology & Bio-Statistics研究設(shè)計(jì)研究設(shè)計(jì)(4) Final Study Population and Study Design (1)nOur final study population consisted of girls and women bor

12、n in Denmark between 1962 and 1993 who were alive and had no history of a mental disorder, defined as inpatient psychiatric contact, 9 months before a first-ever first-trimester induced abortion or first childbirth. nWe excluded girls and women who were born outside Denmark and girls and women emigr

13、ating from Denmark (because of the lack of information on psychiatric admissions outside Denmark) and girls and women with records of psychiatric admission occurring before the 9-month period preceding the abortion or childbirth.Department of Epidemiology & Bio-Statistics Final Study Population

14、and Study Design (2) The girls and women in the final study population were followed individually from 9 months before the first-time first-trimester induced abortion or birth of a live infant through 12 months after the event or until a psychiatric contact occurred for a first mental disorder, unti

15、l death, until emigration, or until December 31, 2007 whichever came first. We included only new psychiatric contacts, and we censored follow-up data on the date of the initial contactDepartment of Epidemiology & Bio-Statistics問題問題n該研究屬于流行病學(xué)中的哪種研究設(shè)計(jì)類該研究屬于流行病學(xué)中的哪種研究設(shè)計(jì)類型？型？n( 討論討論)n流行病學(xué)總共有幾大類科研設(shè)計(jì)方

16、法流行病學(xué)總共有幾大類科研設(shè)計(jì)方法?Department of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-Statistics觀察性研究觀察性研究n 描述性研究描述性研究1.橫斷面調(diào)查2.生態(tài)學(xué)研究3.疾病監(jiān)測(cè)4.病例報(bào)道n 分析性研究分析性研究1.病例對(duì)照2.隊(duì)列研究Department of Epidemiology & Bio-Statistics描述性研究描述性研究研究特定時(shí)點(diǎn)或期間和特定范圍內(nèi)人群中的有關(guān)變研究特定時(shí)點(diǎn)或期間和特定范圍內(nèi)人群中的有關(guān)變量量( (因素因素) )與疾病

17、或健康狀況的關(guān)系。與疾病或健康狀況的關(guān)系。又稱描述性流行病學(xué)。指根據(jù)日常記錄資料或通過又稱描述性流行病學(xué)。指根據(jù)日常記錄資料或通過特殊調(diào)查所得的資料，包括實(shí)驗(yàn)室檢查結(jié)果。按不特殊調(diào)查所得的資料，包括實(shí)驗(yàn)室檢查結(jié)果。按不同地區(qū)、不同時(shí)間及不同人群特征分組，將一個(gè)社同地區(qū)、不同時(shí)間及不同人群特征分組，將一個(gè)社區(qū)人群疾病或健康狀態(tài)分布情況進(jìn)行簡(jiǎn)單描述，常區(qū)人群疾病或健康狀態(tài)分布情況進(jìn)行簡(jiǎn)單描述，常常是流行病學(xué)調(diào)查的第一步，也是分析流行病學(xué)的常是流行病學(xué)調(diào)查的第一步，也是分析流行病學(xué)的基礎(chǔ)。它主要描述分布的三大特征，即：地區(qū)特征、基礎(chǔ)。它主要描述分布的三大特征，即：地區(qū)特征、時(shí)間特征和人群特征。時(shí)間特

18、征和人群特征。 現(xiàn)況調(diào)查現(xiàn)況調(diào)查是一種常用的描述性研究是一種常用的描述性研究 Department of Epidemiology & Bio-Statistics現(xiàn)況研究現(xiàn)況研究 定義定義：現(xiàn)況研究是流行病學(xué)研究方法中的一種基現(xiàn)況研究是流行病學(xué)研究方法中的一種基礎(chǔ)性研究方法。它是按照事先設(shè)計(jì)的要求在某礎(chǔ)性研究方法。它是按照事先設(shè)計(jì)的要求在某一人群中應(yīng)用普查和抽樣調(diào)查的方法收集特定一人群中應(yīng)用普查和抽樣調(diào)查的方法收集特定時(shí)間內(nèi)疾病的描述性資料，以描述疾病的分布時(shí)間內(nèi)疾病的描述性資料，以描述疾病的分布及觀察某些因素與疾病之間的關(guān)聯(lián)。亦可稱為及觀察某些因素與疾病之間的關(guān)聯(lián)。亦可稱為橫斷面調(diào)

19、查橫斷面調(diào)查，或，或患病率調(diào)查患病率調(diào)查。因所收集的有關(guān)。因所收集的有關(guān)因素與疾病或健康之間的資料既不是過去暴露因素與疾病或健康之間的資料既不是過去暴露史，又不是隨訪調(diào)查所得的結(jié)果，而是調(diào)查當(dāng)史，又不是隨訪調(diào)查所得的結(jié)果，而是調(diào)查當(dāng)時(shí)所獲得的資料，故稱它為現(xiàn)況研究。時(shí)所獲得的資料，故稱它為現(xiàn)況研究。 Department of Epidemiology & Bio-Statisticsn掌握目標(biāo)群體中疾病的患病率及其分布狀態(tài)。n提供病因線索。n利用普查或篩檢可實(shí)現(xiàn)疾病的二級(jí)預(yù)防。n確定高危人群。n進(jìn)行疾病監(jiān)測(cè)、預(yù)防接種效果及其他資料質(zhì)量的評(píng)價(jià)。Department of Epidemi

20、ology & Bio-Statistics現(xiàn)況研究的特點(diǎn)現(xiàn)況研究的特點(diǎn)n一般不設(shè)對(duì)照組一般不設(shè)對(duì)照組n關(guān)心的是某一特定時(shí)點(diǎn)或短時(shí)期內(nèi)某一群體中關(guān)心的是某一特定時(shí)點(diǎn)或短時(shí)期內(nèi)某一群體中暴露和疾病的狀況或聯(lián)系。暴露和疾病的狀況或聯(lián)系。 n不能確定暴露與疾病的因果關(guān)系。不能確定暴露與疾病的因果關(guān)系。 n對(duì)固定的暴露因素可作因果推論。對(duì)固定的暴露因素可作因果推論。 n在現(xiàn)在暴露水平與既往變化不大或存在良好相在現(xiàn)在暴露水平與既往變化不大或存在良好相關(guān)性；或已知其變化規(guī)律時(shí)，可用現(xiàn)在的暴露關(guān)性；或已知其變化規(guī)律時(shí)，可用現(xiàn)在的暴露狀態(tài)來代替或估計(jì)過去的暴露狀態(tài)。狀態(tài)來代替或估計(jì)過去的暴露狀態(tài)。 n

21、定期重復(fù)可獲得發(fā)病率資料定期重復(fù)可獲得發(fā)病率資料 Department of Epidemiology & Bio-Statistics現(xiàn)況研究的種類現(xiàn)況研究的種類 p普查普查（Census） 調(diào)查特定時(shí)點(diǎn)或時(shí)期、特定范圍內(nèi)的全部人群調(diào)查特定時(shí)點(diǎn)或時(shí)期、特定范圍內(nèi)的全部人群( (總體總體) )。p抽樣調(diào)查抽樣調(diào)查（Sampling survey） 隨機(jī)抽樣，調(diào)查特定時(shí)點(diǎn)、特定范圍人群的一個(gè)代表隨機(jī)抽樣，調(diào)查特定時(shí)點(diǎn)、特定范圍人群的一個(gè)代表性樣本，以樣本統(tǒng)計(jì)量估計(jì)總體參數(shù)所在范圍。性樣本，以樣本統(tǒng)計(jì)量估計(jì)總體參數(shù)所在范圍。 Department of Epidemiology &

22、 Bio-Statistics生態(tài)學(xué)研究生態(tài)學(xué)研究定義：定義： 描述性研究的一種，從群體的水平上研究描述性研究的一種，從群體的水平上研究某種因素與疾病的關(guān)系，以群體為觀察和某種因素與疾病的關(guān)系，以群體為觀察和分析單位，描述不同人群中某因素的暴露分析單位，描述不同人群中某因素的暴露狀況與疾病的頻率，分析該暴露因素與疾狀況與疾病的頻率，分析該暴露因素與疾病的關(guān)系。病的關(guān)系。 Department of Epidemiology & Bio-Statistics生態(tài)學(xué)研究生態(tài)學(xué)研究1、比較生態(tài)學(xué)研究比較生態(tài)學(xué)研究（ecological comparison study）比較不同人群中某疾病或

23、健康狀態(tài)，他）比較不同人群中某疾病或健康狀態(tài)，他們的疾病率或死亡率的差別，以了解某疾病或健們的疾病率或死亡率的差別，以了解某疾病或健康狀態(tài)在不同人群中分布有無異同點(diǎn)。從而探索康狀態(tài)在不同人群中分布有無異同點(diǎn)。從而探索該現(xiàn)象產(chǎn)生的原因，找到值得進(jìn)一步深入研究的該現(xiàn)象產(chǎn)生的原因，找到值得進(jìn)一步深入研究的線索。線索。2、生態(tài)趨勢(shì)研究生態(tài)趨勢(shì)研究（ecological trend study）指連）指連續(xù)觀察不同人群中某疾病或健康狀態(tài)的發(fā)生率或續(xù)觀察不同人群中某疾病或健康狀態(tài)的發(fā)生率或死亡率，了解其變動(dòng)趨勢(shì)。死亡率，了解其變動(dòng)趨勢(shì)。 Department of Epidemiology & B

24、io-StatisticsDepartment of Epidemiology & Bio-Statistics美國(guó)美國(guó)1900-1999年人均煙草消耗量、男女肺癌死亡率變動(dòng)趨勢(shì)年人均煙草消耗量、男女肺癌死亡率變動(dòng)趨勢(shì)Department of Epidemiology & Bio-Statistics觀察性研究觀察性研究n分析性研究分析性研究1.病例對(duì)照2.隊(duì)列研究Department of Epidemiology & Bio-Statistics病例對(duì)照研究基本原理病例對(duì)照研究基本原理以確診患某種特定疾病的病人作為病例.以不患該病但具有可比性的個(gè)體作為對(duì)照.通過詢

25、問、實(shí)驗(yàn)室檢查或復(fù)查病史，搜集既往 危險(xiǎn)因素暴露史.測(cè)量并比較兩組各因素的暴露比例，經(jīng)統(tǒng)計(jì)學(xué)檢驗(yàn)該因素與疾病之間是否存在統(tǒng)計(jì)學(xué)關(guān)聯(lián).Department of Epidemiology & Bio-Statistics病例對(duì)照研究特點(diǎn)病例對(duì)照研究特點(diǎn)n回顧性n由果因研究n觀察法n不能驗(yàn)證病因Department of Epidemiology & Bio-Statistics時(shí)間病例組對(duì)照組研究開始暴露暴露非暴露非暴露調(diào)查方向圖5-1 病例對(duì)照研究示意圖（Greenberg 2002）注：陰影區(qū)域代表暴露于所研究的危險(xiǎn)因素的研究對(duì)象二、研究示意圖二、研究示意圖Departmen

26、t of Epidemiology & Bio-Statistics病例對(duì)照衍生的研究類型病例對(duì)照衍生的研究類型 巢式病例對(duì)照研究巢式病例對(duì)照研究 單純病例研究單純病例研究 病例時(shí)間對(duì)照設(shè)計(jì)病例時(shí)間對(duì)照設(shè)計(jì) 病例對(duì)照與隊(duì)列研究作為病因研究的主要方法，有病例對(duì)照與隊(duì)列研究作為病因研究的主要方法，有其各自的優(yōu)勢(shì)與不足，而且這些優(yōu)勢(shì)與不足相互補(bǔ)充，其各自的優(yōu)勢(shì)與不足，而且這些優(yōu)勢(shì)與不足相互補(bǔ)充，因此，在實(shí)踐過程中產(chǎn)生了一些新的研究類型，結(jié)合使因此，在實(shí)踐過程中產(chǎn)生了一些新的研究類型，結(jié)合使用這兩種方法，揚(yáng)長(zhǎng)避短。用這兩種方法，揚(yáng)長(zhǎng)避短。病例病例- -隊(duì)列研究隊(duì)列研究病例交叉研究病例交叉研究D

27、epartment of Epidemiology & Bio-Statistics巢式病例對(duì)照研究（巢式病例對(duì)照研究（1）n 基本原理基本原理 按隊(duì)列研究方式進(jìn)行樣本收集。按隊(duì)列研究方式進(jìn)行樣本收集。 選擇一隊(duì)列，收集基線資料，采集所研選擇一隊(duì)列，收集基線資料，采集所研究的生物學(xué)標(biāo)志的組織或體液標(biāo)本儲(chǔ)存究的生物學(xué)標(biāo)志的組織或體液標(biāo)本儲(chǔ)存?zhèn)溆?；備用；隨隨 訪：隨訪到出現(xiàn)能滿足病例對(duì)照研究訪：隨訪到出現(xiàn)能滿足病例對(duì)照研究樣本量的病例數(shù)為止；樣本量的病例數(shù)為止；Department of Epidemiology & Bio-Statistics巢式病例對(duì)照研究（巢式病例對(duì)照研究（

28、2）匹配：匹配：按病例進(jìn)入隊(duì)列的時(shí)間、疾病出現(xiàn)時(shí)間按病例進(jìn)入隊(duì)列的時(shí)間、疾病出現(xiàn)時(shí)間與性別、年齡等匹配條件，從同一隊(duì)列選擇與性別、年齡等匹配條件，從同一隊(duì)列選擇1 1個(gè)個(gè)或數(shù)個(gè)非病例作對(duì)照，抽取病例與對(duì)照的基線或數(shù)個(gè)非病例作對(duì)照，抽取病例與對(duì)照的基線資料并檢測(cè)收集的標(biāo)本資料并檢測(cè)收集的標(biāo)本資料處理：資料處理：按匹配病例對(duì)照研究方法處理資料按匹配病例對(duì)照研究方法處理資料Department of Epidemiology & Bio-Statistics病例病例-隊(duì)列研究隊(duì)列研究基本原理基本原理 n研究開始時(shí)，在隊(duì)列中隨機(jī)選取一組樣本作為對(duì)照組；n觀察結(jié)束時(shí)，隊(duì)列中出現(xiàn)被研究疾病所有病例

29、作病例組；n與隨機(jī)對(duì)照組進(jìn)行比較；n這種研究模式，可同時(shí)研究幾種疾病，不同疾病有不同病例組，但對(duì)照組都是同一組隨機(jī)樣本Department of Epidemiology & Bio-Statistics病例病例-隊(duì)列與巢式病例對(duì)照研究的隊(duì)列與巢式病例對(duì)照研究的區(qū)別區(qū)別n對(duì)照是隨機(jī)選取，不與病例進(jìn)行匹配。n隨機(jī)對(duì)照組中成員如發(fā)生被研究疾病，既為對(duì)照，又同時(shí)為病例。n1個(gè)隨機(jī)對(duì)照組可以同時(shí)和幾個(gè)病例組比較分析。Department of Epidemiology & Bio-Statistics n 因果關(guān)系清楚(符合時(shí)間順序)n 資料可靠（實(shí)時(shí)記錄數(shù)據(jù)）n 論證強(qiáng)度高（前瞻性隊(duì)

30、列研究設(shè)計(jì)）n 省時(shí)省力省錢（不需要收集典型cohort研究那么多樣本量）n 適合于分子流行病學(xué)研究Department of Epidemiology & Bio-Statistics背背 景：景：19941994年年P(guān)iegorseh、Begs等提出等提出 遺傳與環(huán)境的關(guān)系遺傳與環(huán)境的關(guān)系 交互作用交互作用 病例對(duì)照研究和隊(duì)列研究的效率費(fèi)用病例對(duì)照研究和隊(duì)列研究的效率費(fèi)用 病例病例- -病例研究病例研究 應(yīng)用前提條件：應(yīng)用前提條件： 在正常人群中基因型與環(huán)境暴露各自獨(dú)立發(fā)生在正常人群中基因型與環(huán)境暴露各自獨(dú)立發(fā)生 所研究疾病為罕見病所研究疾病為罕見病( (此時(shí)可用此時(shí)可用OROR來

31、估計(jì)來估計(jì)RRRR值值) )Department of Epidemiology & Bio-Statistics研究示意圖研究示意圖單純病例研究單純病例研究環(huán)境暴露環(huán)境暴露基因型基因型病人病人+ +- -+ +- -+ +- -Department of Epidemiology & Bio-Statistics OR=ad/bcOR=ad/bc當(dāng)當(dāng)ORge1ORge1時(shí)時(shí), , 有正相乘模型交互作用有正相乘模型交互作用當(dāng)當(dāng)ORge=1ORge=1時(shí)時(shí), , 無相乘模型交互作用無相乘模型交互作用當(dāng)當(dāng)ORge1ORge未暴露組的率，則可認(rèn)為暴露與疾病存在聯(lián)系，可能是因果聯(lián)系。D

32、epartment of Epidemiology & Bio-StatisticsN目標(biāo)人群目標(biāo)人群代表性代表性樣本樣本YE時(shí)間順序時(shí)間順序 暴露暴露結(jié)局結(jié)局YNDepartment of Epidemiology & Bio-Statistics隊(duì)列研究的類型隊(duì)列研究的類型n根據(jù)研究對(duì)象進(jìn)入隊(duì)列的時(shí)間：固定隊(duì)列動(dòng)態(tài)隊(duì)列n根據(jù)研究設(shè)計(jì)的時(shí)間點(diǎn)：前瞻性隊(duì)列研究前瞻性隊(duì)列研究(prospective cohort study) 歷史性隊(duì)列研究歷史性隊(duì)列研究(historical cohort study）雙向性隊(duì)列研究雙向性隊(duì)列研究(ambispective cohort stu

33、dy) Department of Epidemiology & Bio-Statistics固定隊(duì)列固定隊(duì)列 Fixed Cohort研究開始研究開始研究結(jié)束研究結(jié)束出現(xiàn)結(jié)局出現(xiàn)結(jié)局未出現(xiàn)結(jié)局未出現(xiàn)結(jié)局Department of Epidemiology & Bio-Statistics動(dòng)態(tài)隊(duì)列動(dòng)態(tài)隊(duì)列 Dynamic Cohort研究開始研究開始研究結(jié)束研究結(jié)束出現(xiàn)結(jié)局出現(xiàn)結(jié)局失訪失訪Department of Epidemiology & Bio-Statistics時(shí)間順序時(shí)間順序 過去過去 現(xiàn)在現(xiàn)在 將來將來 歷史性隊(duì)列歷史性隊(duì)列雙向性隊(duì)列雙向性隊(duì)列前瞻性隊(duì)列

34、前瞻性隊(duì)列前瞻性收集資料前瞻性收集資料根據(jù)研究設(shè)計(jì)的時(shí)間點(diǎn)分類根據(jù)研究設(shè)計(jì)的時(shí)間點(diǎn)分類Department of Epidemiology & Bio-Statistics主要特點(diǎn)主要特點(diǎn)觀察法設(shè)立對(duì)照 由因到果，符合時(shí)間順序確證暴露和結(jié)局因果關(guān)系Department of Epidemiology & Bio-Statistics “Induced First-Trimester Abortion and Risk of Mental Disorder”是什么設(shè)計(jì)類型？ 病例時(shí)間對(duì)照設(shè)計(jì) Department of Epidemiology & Bio-Statist

35、icsOutcome of interestnThe outcome of interest was the first psychiatric contact (inpatient admission or outpatient visit) for any mental disorder. nWe compared the 12-month period after the abortion or childbirth with the 9-month period before the event, treating the period before the event as a se

36、parate category in analyses. nFor the main analyses of incidence-rate ratios, the reference category was the period from 9 to 0 months before abortion or childbirth.Department of Epidemiology & Bio-StatisticsStatistical AnalysisnEach subject was followed individually by means of survival-analysi

37、s techniques. nThis method approximates a Cox regression.nWe compared the incidence of a first psychiatric contact (per 1000 person-years) between different time periods by calculating incidence-rate ratios, which can be interpreted as relative risks.nAge, calendar period, parity status (0 vs. 1 chi

38、ld at the time of abortion), time since birth or abortion, and presence or absence of a history of mental disorders in parents of the girls and women in the study population were treated as time-dependent variables in prespecified categories.nKaplanMeier estimates of disease-free survival were also

39、plotted for the study population.nIn addition, we evaluated age, parity status, and presence or absence of a history of mental disorders in the parents as potential effect modifiers by conducting stratified analyses and tests for interaction involving the comparison of the risk of a psychiatric cont

40、act in each stratum. Department of Epidemiology & Bio-StatisticsResultsDepartment of Epidemiology & Bio-StatisticsPsychiatric Contact before and after abortionnFrom 1995 to 2007, a total of 84,620 girls and women had a first-time first-trimester induced abortion. nOf these girls and women, 8

41、68 (1.0%) had a first psychiatric contact during the 9 months before the abortion, as did 1277 (1.5%) within the 12 months after the abortion.nIncidence rates of psychiatric contacts were 14.6 (95%CI=13.7 -15.6) per 1000 person-years before abortion and 15.2 (95% CI=14.4-16.1) per 1000 person-years

42、after abortion.Department of Epidemiology & Bio-StatisticsPsychiatric Contact before and after ChildbirthnDuring the same study period, a total of 280,930 girls and women gave birth to their first live-born child. nOf these girls and women, 790 (0.3%) had a first-time psychiatric contact within

43、the 9 months preceding delivery, as did 1916 (0.7%) from 0 through 12 months post partum.nIncidence rates of psychiatric contacts were 3.9 (95% CI=3.7 - 4.2) per 1000 person-years before childbirth and 6.7 (95% CI=6.4 - 7.0) per 1000 person-years after childbirth.nThe risk of a psychiatric contact d

44、id not differ significantly before and after abortion (P = 0.19);nbut the risk after childbirth was significantly greater than the risk before childbirth (P0.001).Department of Epidemiology & Bio-StatisticsCumulative Incidence - CI (proportion)The proportion of the population who gets the diseas

45、e during a given time periodThe risk that a randomly chosen individual will get the disease during the time periodnumber of new cases during the time periodnumber of individuals in the populationR = 0 to 1, or percent, per million etc., but the period must be statedR = KDepartment of Epidemiology &a

46、mp; Bio-StatisticsIncidence Rate - IRNumber of NEW cases of diseaseTotal person- time of observation Proportion of the population that acquire or develop a diseases in a period of time Speed of developing a diseaseDenominator:- is a measure of time - the sum of each individuals time at risk and free

47、 from diseaseDepartment of Epidemiology & Bio-StatisticsCumulative Incidence Incidence Rate1997199819992000200120022003l ll lllPerson 134631421 p.yPerson 2Person 3Person 4Person 5Person 6= 3 cases / 6 persons = 50%= 3 cases / 21 person-years = 0.14= 14 cases / 100 person-yearsDepartment of Epide

48、miology & Bio-StatisticsDepartment of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-StatisticsRisk of Psychiatric Contact with Abortion versus Risk with ChildbirthDepartment of Epidemiology & Bio-StatisticsIR among subjects without eventsnThe incidence rate of psychia

49、tric contact among girls and women who did not deliver a child or have an abortion during the entire study period was 8.2 (95% CI, 8.2 to 8.3) per 1000 person-years.Department of Epidemiology & Bio-StatisticsnIn our study population, the incidence rates of psychiatric contact changed around the

50、time of childbirth but not around the time of abortionDepartment of Epidemiology & Bio-Statistics混雜因素的考慮混雜因素的考慮nIn 2006, the median ages of the girls and women who had an abortion and those who gave birth were 25.8 years and 28.8 years, respectively.nTo account for the difference in age distribu

51、tion and changes during the follow-up period, we calculated incidence-rate ratios with adjustment for age and calendar period.Department of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-StatisticsnAdditional analyses to assess wh

52、ether the results differed on the basis of the subgroup of mental disorders. (Table 1 and 2)Department of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-StatisticsDepartment of Epidemiology & Bio-Statisticsn既往研究提示：既往研究提示：Mental health problems after abortion have been repo

53、rted to be more frequent in young women than in older women, and a mental disorder in a parent increases the risk of a mental disorder in the offspring, including the risk of a postpartum disorder. n本研究結(jié)果：本研究結(jié)果：However, the effect of time relative to abortion on the risk of a psychiatric contact was not significantly affected by age (P = 0.89 for interaction), parity status (P = 0.09 f