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1、观察性研究方法设计及实例,余运贤 浙大医学院流行病学与统计学学科 Tel：88208191 Email：,Induced First-Trimester Abortion and Risk of Mental Disorder,Author: Munk-Olsen T, Laursen TM, Pedersen CB, Lidegaard , Mortensen PB. Journal: N Engl J Med. 2011;364(4):332-9. Published date: 2011 Jan 27,案例,背景和目的,Background： Concern has been expre
2、ssed about potential harm to womens mental health in association with having an induced abortion (人工流产), but it remains unclear whether induced abortion is associated with an increased risk of subsequent psychiatric problems Aim: Assess the risk of a first psychiatric contact (精神症状) after first-trim
3、ester induced abortion, as compared with before the event; we also looked at the risk of a first psychiatric contact after, as compared with before, childbirth(分娩).,研究设计(1),Study Population Data from the Danish Civil Registration System (CRS), which holds information on all Danish residents, was use
4、d to establish an underlying study population of all girls and women born in Denmark between 1962 and 1993 who were alive on their 15th birthday, for a total of 954,702 girls and women. The CRS was established in 1968, when data were recorded for all people alive and residing in Denmark. Among other
5、 variables, it includes each residents personal identification number (CRS number), which is assigned to all Danes(丹麦人) at birth or immigration, sex, date of birth, parents CRS numbers, and daily updated information on vital status.,研究设计(2),Mental Disorders The Danish Psychiatric Central Register co
6、vers information on mental disorders in the girls and women in our study population and their parents. There 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(
7、icd-10)from 1995. The 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.,研究设计(3),Induced Abortions The Danish National Regi
8、ster 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. From this register, we obtained the dates of first-trimester medical or sur
9、gical induced abortions. Girls 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. To further ensure that all induced abortions in the study populat
10、ion were first-time abortions, we restricted the population to women and girls born in 1962 or later.,研究设计(4),Final Study Population and Study Design (1) Our final study population consisted of girls and women born in Denmark between 1962 and 1993 who were alive and had no history of a mental disord
11、er, defined as inpatient psychiatric contact, 9 months before a first-ever first-trimester induced abortion or first childbirth. We excluded girls and women who were born outside Denmark and girls and women emigrating from Denmark (because of the lack of information on psychiatric admissions outside
12、 Denmark) and girls and women with records of psychiatric admission occurring before the 9-month period preceding the abortion or childbirth.,Final Study Population and Study Design (2),The girls and women in the final study population were followed individually from 9 months before the first-time f
13、irst-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, until death, until emigration, or until December 31, 2007 whichever came first. We included only new psychiatric contacts, and we censored
14、follow-up data on the date of the initial contact,问题,该研究属于流行病学中的哪种研究设计类型？ ( 讨论) 流行病学总共有几大类科研设计方法?,观察性研究,描述性研究 横断面调查 生态学研究 疾病监测 病例报道 分析性研究 病例对照 队列研究,描述性研究,研究特定时点或期间和特定范围内人群中的有关变量(因素)与疾病或健康状况的关系。 又称描述性流行病学。指根据日常记录资料或通过特殊调查所得的资料，包括实验室检查结果。按不同地区、不同时间及不同人群特征分组，将一个社区人群疾病或健康状态分布情况进行简单描述，常常是流行病学调查的第一步，也是分析流
15、行病学的基础。它主要描述分布的三大特征，即：地区特征、时间特征和人群特征。 现况调查是一种常用的描述性研究,现况研究,定义：现况研究是流行病学研究方法中的一种基础性研究方法。它是按照事先设计的要求在某一人群中应用普查和抽样调查的方法收集特定时间内疾病的描述性资料，以描述疾病的分布及观察某些因素与疾病之间的关联。亦可称为横断面调查，或患病率调查。因所收集的有关因素与疾病或健康之间的资料既不是过去暴露史，又不是随访调查所得的结果，而是调查当时所获得的资料，故称它为现况研究。,现况研究的目的,掌握目标群体中疾病的患病率及其分布状态。 提供病因线索。 利用普查或筛检可实现疾病的二级预防。 确定高危人群
16、。 进行疾病监测、预防接种效果及其他资料质量的评价。,现况研究的特点,一般不设对照组 关心的是某一特定时点或短时期内某一群体中暴露和疾病的状况或联系。 不能确定暴露与疾病的因果关系。 对固定的暴露因素可作因果推论。 在现在暴露水平与既往变化不大或存在良好相关性；或已知其变化规律时，可用现在的暴露状态来代替或估计过去的暴露状态。 定期重复可获得发病率资料,现况研究的种类,普查（Census） 调查特定时点或时期、特定范围内的全部人群(总体)。 抽样调查（Sampling survey） 随机抽样，调查特定时点、特定范围人群的一个代表性样本，以样本统计量估计总体参数所在范围。,生态学研究,定义： 描述性研究的一种，从群体的水平上研究某种因素与疾病的关系，以群体为观察和分析单位，描述不同人群中某因素的暴露状况与疾病的频率，分析该暴露因素与疾病的关系。,生态学研究,类型： 1、比较生态学研究（ecological comparison study）比较不同人群中某疾病或健康状态，他们的疾病率或死亡率的差别，以了解某疾病或健康状态在不同人群
