哈爾濱醫(yī)科大-描述性研究課件

1、描述性研究 Descriptive Study哈爾濱醫(yī)科大學(xué)流行病學(xué)教研室 Department of epidemiology ，Harbin Medical University1Methods of studyObservational ExperimentalTheoreticalDescriptive studyAnalytic studyClinical trialField trialCommunity interventionthree types of basic methodsCase-control studyCohort studyCross-sectional stu

2、dyEcological study2Epidemiology is the study of the distribution and determinants of disease frequency in human population.Epidemiology: Principles and Methodsby Brian MacMahon 19963?The distribution of Disease considers Who is getting disease? Where is disease occurring? When is disease occurring?4

3、PersonPlaceTimeCasesDescriptive Epidemiology Who? Where? When? 5目 錄 現(xiàn)況研究的概述 現(xiàn)況研究的設(shè)計(jì)與實(shí)施研究實(shí)例生態(tài)學(xué)研究Introduction of cross-sectional studyDesign and implementation of cross-sectional studyA case studyEcological studyOutline7第一節(jié) 現(xiàn)況研究概述 Introduction of Cross-sectional Study 基本概念目的與應(yīng)用特點(diǎn)與類型Basic concept Mecha

4、nism Purposes and applications Characteristics and categories 8TimeDZDZEE-10TimeSchematic diagram of Cross-sectional StudyT1T2T311 掌握目標(biāo)群體中疾病或健康狀況的分布 提供疾病病因研究的線索 二、目的與應(yīng)用 Mechanism Purposes and applications Describes the distributing of disease or health events within populations To provide etiologica

5、l clues12 確定高危人群 評價疾病監(jiān)測、預(yù)防接種等防治措施效果 二、目的與應(yīng)用 Mechanism Purposes and applications To identify high risk groups in the population To evaluate the effect of surveillance，vaccination and disease prevention and control14 研究特點(diǎn)開始時一般不設(shè)對照組現(xiàn)況研究的特定時間在確定因果聯(lián)系時受到限制對不會發(fā)生改變的暴露因素，可以提示因果聯(lián)系三、特點(diǎn)與類型 Characteristics and c

6、ategories CharacteristicsNo control group Particular point of timeLimit to ensure the causal relationshipTo prompt causal relationship for the exposures that wont be changed15The census of the lifetime alcohol drinking status in America population17 明確調(diào)查目的和類型 確定研究對象 確定樣本量和抽樣方法 資料的收集 資料的整理與分析 常見偏倚及其控

7、制 研究的優(yōu)點(diǎn)與局限性第二節(jié) 現(xiàn)況研究的設(shè)計(jì)與實(shí)施Design and implementation of cross-sectional studyTo make the purpose and category of studyTo select the objectsTo determine the sample size and sampling methodTo collect data To sort and analyze dataBias and controlAdvantage and limitation一、明確調(diào)查目的和類型To make the purpose and

8、category of study根據(jù)研究提出的問題，明確調(diào)查目的根據(jù)具體研究目的確定是普查還是抽樣調(diào)查 To make the purpose by the proposal of the study To select the survey method reference to the aim, census or sampling survey.19二、確定研究對象To select the objects某個區(qū)域內(nèi)的全體居民或其中一部分某一時點(diǎn)上的流動人員某些特殊群體Entire or part of the population in a regionFloating popula

9、tion at a particular point of time. Certain special groups of people20三、確定樣本量和抽樣方法 To determine the sample size and sampling method 確定樣本量 預(yù)期現(xiàn)患率 ( P ) 允許誤差（d） 顯著性水平（）To determine the sample size Expected prevalence( P ) Allowable error（d） Significance level（）計(jì)量資料樣本大小估計(jì)公式Formulas for Numerical data計(jì)數(shù)資

10、料樣本大小估計(jì)公式Formulas for Categorical data 22 非隨機(jī)抽樣 Non-random sampling 選擇樣本時，加入人主觀因素，使總體中每個個體被抽取的機(jī)會是不均等的Non-random samples are selected by any kind of procedure that does not give all cases in the population equal chances to fall into the sample. 隨機(jī)抽樣 Random sampling總體中每一個對象都有同等機(jī)會被選入作為研究對象Every person

11、in the target population has the same known (and non-zero) chance of being included in the survey25單純隨機(jī)抽樣(簡單隨機(jī)抽樣)最簡單、最基本的抽樣方法從總體N個對象中，利用抽簽或其他隨機(jī)方法抽取n個總體中每個對象被抽到的概率相等 Simple random samplingSimplest and basic methodTo select number n subjects by drawing lot or by using a table of random number from pop

12、ulation with N units Equal chance for each subject in the target population 27圖31 總體與樣本示意圖Fig 31 Diagram of population and sample28系統(tǒng)抽樣(機(jī)械抽樣)將總體各個個體單位按某種標(biāo)志排列、連續(xù)編號根據(jù)總體數(shù)N和確定的樣本數(shù)n，計(jì)算抽樣距離（N/n） Systemic samplingRank every units by a character construct and number themDefine the size of the sample and cal

13、culate sampling interval (k = N/n)29系統(tǒng)抽樣(機(jī)械抽樣)3. 用單純隨機(jī)方法在第一組中確定一個起始號4. 從此起始點(diǎn)開始，每隔K（K=N/n）個單位抽取一個作為研究對象 Systemic sampling3. Draw a random number ( k) for starting 4. Draw every k units from first unit30圖32 系統(tǒng)抽樣示意圖Fig 32 Diagram of systemic sampling31Example: Systematic sampling32整群抽樣Cluster samplingT

14、he entire population of interest is divided into groups, or clusters, and a random sample of these clusters is selected.單純整群抽樣（Simple cluster sampling）二階段抽樣（Two stages sampling） 將總體分成若干群組，抽取其中部分群組作為觀察單位組成樣本33圖33 整群抽樣示意圖Fig 33 Diagram of cluster sampling34Section 4Section 5Section 3Section 2Section 1

15、Example: Cluster sampling35分層抽樣Stratified samplingFirst, stratify the population into several strata by character of areas, ages, etc. then select objects using random sampling in each strata. 將總體單位按某種特征分為若干次級（層），然后從每一層內(nèi)單純隨機(jī)抽樣組成一個樣本。36分層抽樣Stratified sampling 按比例分配（proportional allocation） 最優(yōu)分配（optim

16、um allocation)37圖34 分層抽樣示意圖Fig 33 Diagram of cluster sampling38Example: stratified sampling39多級抽樣將抽樣過程分階段進(jìn)行，每個階段使用的抽樣方法往往不同，即將以上抽樣方法結(jié)合使用，在大型流行病學(xué)調(diào)查中常用。 Multistage samplingMulti-stage sampling is a kind of complex sample design in which two or more levels of units are imbedded one in the other. 40一級抽樣

17、單位Primary units 二級抽樣單位Secondary units多級抽樣 Multistage sampling41檢查資料完整性和準(zhǔn)確性 按標(biāo)準(zhǔn)歸類、核實(shí) 五、資料的整理與分析Data sort and analysis Check the integrity and accuracy of data Classify and verify data by standard42Target Population or Sampling FrameCensus or Sampling SurveySampleDiseaseAndExposureNon-diseaseandExposu

18、reNon-diseaseandNon-exposureDiseaseandNon-exposure4344Example:Job A (hazardous)100 Workers80 Healthy20 Respiratory symptoms80 well10 wellJob B (hazardous)100 Workers95 Healthy5 Respiratory symptoms95 well15 wellPoint YPoint XPrevalence rate of respiratory symptoms in Job A20%(20/100)11%(10/90)Preval

19、ence rate of respiratory symptoms in Job B5%(5/100)14%(15/110)Ratio of prevalence rates, Job A/Job B:4.00.8Cork and Kerry Diabetes & Heart Disease Study, 1998Prevalence of hypertension by age and sex46Example of Cross-Sectional StudyHypothesis:Obesity is a risk factor for knee osteoarthritisSample:

20、100 retirees living at “University Village”47Medical exam + X-rays to diagnose osteoarthritis of the kneeOsteoarthritis+-40102030+-Obesity505048Prevalence of osteoarthritis among obese subjects: 40/50 = 0.8Prevalence of osteoarthritis among non-obese subjects: 20/50 = 0.4Prevalence ratio = 0.8/0.4 =

21、 2.049Obese subjects are two times more likely to have osteoarthritis of the knee than non-obese subjects.50Cross-Sectional StudyWhat came firstly?Obesity or Osteoarthritis？Chicken or egg dilemma ?51 常見的偏倚 偏倚的控制六、偏倚及其控制 Common type of bias Control of bias常見的偏倚 Common type of bias選擇偏倚選擇性偏倚無應(yīng)答偏倚幸存者偏倚信

22、息偏倚回憶偏倚報告偏倚測量偏倚Selection BiasSelection biasNon-response bias Survivor biasInformation BiasRecall biasReport biasMeasurement bias53確保隨機(jī)化原則提高研究對象的依從性和受檢率正確選擇測量工具和檢測方法培訓(xùn)調(diào)查員做好資料的復(fù)查復(fù)核工作辨析混雜因素偏倚的控制 Control of biasPrinciple of randomizationTo improve the compliance of subjects and examination rateTo apply

23、proper measurement tools and test methodsTraining investigatorsReview data carefullyDistinguish and analyze confounding factors 54 優(yōu) 點(diǎn) Advantage常用抽樣調(diào)查，結(jié)果有較強(qiáng)推廣意義有來自同一群體的自然形成的同期對照組，結(jié)果具有可比性可同時觀察多種因素三、研究的優(yōu)點(diǎn)和局限性 Advantage and limitationCommon sampling survey with strong extension results With a control g

24、roup from the same group over the same period formed naturallyCan observe a variety of factors simultaneously55難以確定先因后果的時相關(guān)系不能獲得發(fā)病率資料難以調(diào)查死亡病例、病程短、已痊愈的病例 局 限 性 LimitationDo not establish the true temporal sequence of events.Does not yield incidence or true relative risk.They are not feasible for the

25、cases of death, recovery and short course.第三節(jié) 研究實(shí)例 Example 研究背景 Background 研究方法 Study Method 研究結(jié)果 Results57 “反 應(yīng) ?！?災(zāi) 難Thalidomide Disaster58研究背景Background20世紀(jì)50年代，科學(xué)家推出一種新藥，據(jù)說它能在妊娠期控制精神緊張，防止孕婦惡心，并且有安眠作用。這藥名叫“反應(yīng)?！保ㄉ忱劝?、酞胺哌啶酮）。Introduced in 1956 as sedative (sleeping pill) and to reduce nausea and vo

26、miting during pregnancy，named Thalidomide59研究背景Background 醫(yī)生們對很多新生兒四肢缺如或畸形開始產(chǎn)生警覺，究其原因是孕婦服用了“反應(yīng)停”。 該藥在1961年被禁用 全世界約有8000名嬰兒已經(jīng)受害 Discovered to be a human teratogen causing absence of limbs or limb malformations in newborns Withdrawn in 1961 About 8000 infants effected60分子式Molecular formula 反應(yīng)停 Thalido

27、mide61主要畸形個人觀察信訪例數(shù)%例數(shù)%手臂4352.410350.7手臂與腿2328.16029.6手臂、腿、耳22.473.4手臂與耳33.7104.9耳78.5146.9腿11.242.0其他畸形33.752.5合 計(jì)42203反應(yīng)停引起的主要畸形的構(gòu)成比Ratio of deformities induced by Thalidomide62合并畸形例數(shù)合并畸形例數(shù)幽門2無腦2十二指腸狹窄3心臟17十二指腸閉鎖3小腦3食道閉鎖2眼1肛門閉鎖17鼻1203個短肢畸形病例中合并其他畸形203 cases of phocomelia associated with other malfo

28、rmations63國家反應(yīng)停銷售量（公斤）短肢畸形病例數(shù)奧地利2078比利時25826英國5769349荷蘭14025挪威6011葡萄牙372瑞士1136西德300995000美國2510+7* 反應(yīng)停從國外購來 (Thalidomide purchased from other countries)反應(yīng)停銷售量與短肢畸形數(shù)的關(guān)系Relationship between sales of Thalidomide and numbers of phocomelia64短肢畸形例數(shù)反應(yīng)停銷售量（占銷售總量的比例）510152019581959196019611962年 50100150西德反應(yīng)停

29、銷售總量（虛線）與短肢畸形例數(shù)（實(shí)線）的時間分布Time distribution of Thalidomide sales (dotted line) and phocomelia numbers (solid line) in West Germany65 “反應(yīng)停兒童”的事件是一次慘痛的教訓(xùn)。它提醒人們，任何新藥在用于臨床之前必須經(jīng)過徹底檢驗(yàn)。Resulted in new drug testing rules！66 概 念 研究目的 研究類型 優(yōu)點(diǎn)與局限 研究實(shí)例第四節(jié) 生態(tài)學(xué)研究Ecological StudyDefinitionPurposeCategoryAdvantage an

30、d limitationA case study 描述性研究的一種 群體的水平上研究某種因素與疾病的關(guān)系 A descriptive study Focus on the relationship between exposure factors and disease based on population一、概念 Definition68 以群體為觀察和分析單位 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病的關(guān)系 一、概念 Definition Unit of observation and analysis is a population rather than an

31、 individual. Descript the frequency of exposure and disease to analyze the relationship between them in different population. 69 提供病因線索，產(chǎn)生病因 假設(shè) 評估人群干預(yù)措施的效果二、研究目的Aims of study To provide etiological clues and generate hypotheses for analytic studies Evaluate the effect of interventions among populati

32、on 生態(tài)比較研究 生態(tài)趨勢研究三、研究類型Ecological comparison studyEcological time trends study Types of study71應(yīng)用較多的一種方法最簡單的方法觀察不同人群或地區(qū)某種疾病的分布，根據(jù)疾病分布的差異，提出病因假設(shè) 生態(tài)比較研究 Ecological comparison study A method applied frequentlySimplestTo observe the difference between the distributions of groups or regions, to generated

33、the hypothesis according to the distribution.72 生態(tài)趨勢研究 Ecological trend studyTo investigate the temporal relationship between the exposure and disease by observing and comparing the fluctuations of average exposure level and frequency changes of disease in a population，finding the fluctuations trend

34、.連續(xù)觀察不同人群中某因素平均暴露水平的改變和(或)某種疾病發(fā)病率、死亡率變化的關(guān)系，了解變動趨勢，比較暴露水平變化前后疾病頻率的變化情況，判斷某因素與某疾病的聯(lián)系73經(jīng)濟(jì)，出結(jié)果快提供病因未明疾病的病因線索對個體劑量無法測量的情況，是唯一可供選擇的方法 優(yōu) 點(diǎn)四、優(yōu)點(diǎn)與局限Strengths and limitationsQuick, inexpensive, does not require time consuming data collection Can help in formulating hypothesis for the disease of unknown etiology The only way to the Circumstances of individual doses can not be measured Strengths適用于研究因素暴露變異范圍小，較難測量暴露與疾病的關(guān)系人群干預(yù)措施的評價及估計(jì)疾病發(fā)展趨勢 優(yōu) 點(diǎn)四、優(yōu)點(diǎn)與局限Strengths and limitations Strengths Applies to study the exposures with narrow range of va