流行病学题库 实习指导答案

实习一疾病频率测量的常用指标五练习题（一）名词解释：答案见课本P16-22（二）单选题1 B2 B3 E4 C5 B（三）论述题：答案见课本P17-18实习二疾病分布五练习题（一）名词解释：答案见课本P16-22（二）单选题1 B2 C（三）多选题1 ABD2 ABD3 ABDE4 ABCD5 BCDE（四）论述题：1. 答案见课本P262. 答案见课本P33-343. 答案见课本P35-364. 答案见课本P28实习三现况研究课题一问题：现况研究是描述性研究中的一种，此研究属于现况研究中的抽样调查，常用的抽样方法主要有单纯随机抽样、系统抽样、分层抽样、整群抽样和分级抽样。

本次调查的目的是了解该城区居民慢性非传染性疾病的患病情况。

课题二问题1：本次调查属于现况研究中的普查，是一种描述性研究。

问题2：普查的优点普查能掌握疾病的分布情况，明确流行特征和相关的流行因素，提供病因线索。

可普及医学科学知识教育，可发现人群中的全部病例，有利管理和治疗。

普查的缺点由于工作量大，常出现漏查调查对象，工作不易深入细致，不适合患病率很低的疾病，成本高，只能获得患病率的资料。

主要用途①早期发现病人；②了解疾病分布；③了解人群健康水平；④建立某生理指标的正常值。

课题三发病率与患病率的区别：①发病率分子为新发病例；患病率分子为调查时所有新旧病例；②应用范围：发病率应用广，既适用于病程短的疾病，也适用于病程长的慢性病。

现况研究调查的是某一时点的是否患病的情况，不能得到发病率资料，不能计算发病率。

本研究中该城区超重和肥胖的患病率随年龄增长呈上升趋势。

课题四问题1：性别年龄别分布特点：糖尿病的年龄别患病率均随年龄增长而上升, 30 岁以上人群的糖尿病患病率明显增高。

在45 岁以前,男性糖尿病的患病率明显高于女性, 而45 岁以上女性糖尿病的患病率上升较快,60～65 岁期间达到高峰。

地区分布特点：农村的患病率均明显低于城市,这可能与农民主要从事体力活动有关,亦可能与城乡饮食结构的差异有关。

问题2：①体力活动从事体力活动少的职业人群糖尿病患病率最高。

轻度活动和不活动者比中等程度活动者糖尿病的患病率高。

②吸烟既往吸烟而现已戒烟者的糖尿病/ 糖耐量低减患病率最高，但吸烟者的糖耐量低减患病率反而低于不吸烟者。

③饮酒既酒者的糖尿病/ 糖耐量低减患病率最高, 饮酒者与不饮酒者差别不大。

五练习题一单选题1.C2.B3.E4.E5.C6.E7.D8.E二、多选题1. ABCDE2. ABDE3. ABC4. ABCDE5. ABD6. ABCDE三简答题1.现况研究的目的：(1)掌握目标群体中疾病的患病率及其分布状态；（2）提供疾病的致病因素的线索；（3）确定高危人群；（4）对疾病监测、预防接种效果及其他资料质量的评价。

现况研究的特点：(1)开始时一般不设对照组；（2）研究某特定时点或时期内某一群体中暴露和疾病的联系；（3）现况研究揭示暴露与疾病之间的统计学联系，仅为建立因果关系提供线索，是分析性研究的基础，不能以此作因果推论；而对不会发生改变的暴露因素，可以作因果推论；（4）用现在的暴露来替代或估计过去情况的条件；（5）现况研究重复进行可以获得发病率资料。

2. 现况研究常用的抽样方法有：(1)单纯随机抽样；（2）系统抽样；（3）分层抽样；（4）整群抽样；（5）多级抽样。

3.决定现况研究的样本大小的因素来自多方面，但主要是：①预期的患病率，如现患率越靠近50％，样本含量就越小；反之，则要大些。

②对调查结果精确性的要求，即允许误差越大，则所需样本就越小。

四论述题1.现况研究的常见偏倚有（1）选择偏倚：①选择性偏倚；②无应答偏倚；③幸存者偏倚。

（2）信息偏倚：①调查对象引起的偏倚；②调查员偏倚；③测量偏倚。

防止产生偏倚的措施：（1）正确的研究设计：随即化、标准化方法，研究变量的选择及测量（2）提高研究对象的依从性（3）培训研究人员（4）严格校正仪器（5）严格实验条件及研究方法。

2. 普查的目的：（1）早期发现病人；（2）了解疾病分布；（3）了解人群健康水平；（4）建立某生理指标的正常值。

普查适用于那些有一定患病率，危害严重且有简便易行的诊断手段，而早期发现后能有满意治疗效果的疾病；建立某生理指标正常值需要用普查。

普查的优点：（1）确定调查对象上比较简单；（2）可查出某人群中患某病的所有病人，使其得到及时治疗；（3）开展干预如健康教育，了解某病的患病率或健康状况。

普查的缺点：（1）普查对象多，调查期限短难免漏查；（2）调查质量不易控制；（3）患病率低、诊断技术复杂的疾病不易进行普查。

抽样调查的优点：省时间、省人力、省物力，调查结果准确。

抽样调查的缺点：设计、实施及资料分析比普查复杂；重复或遗漏不易被发现；对于变异过大的材料和需要普查普治的情况则不适合用抽样调查；患病率太低的疾病也不适合抽样调查。

实习四队列研究(一) 名词解释▪Exposure, Risk factor，outcome▪Cohort, Birth cohort, Exposure cohort▪Fixed cohort, Dynamic cohort or open cohort▪Cohort study/Prospective study /Follow-up study /Longitudinal study /Incidence study▪Prospective cohort study or concurrent cohort study, Historical (Retrospective or non-concurrent ) Cohort Study, Ambispective (or mixed) cohort study ▪Person time▪Risk, Cumulative incidence, Incidence density▪Standardized mortality ratio (SMR)▪Re1ative risk (RR), risk ratio (RR)，rate ratio (RR)▪Attributable risk (AR), rate difference (RD), excess risk▪Attributable risk percent (AR％) etiologic fraction (EF)▪Population attributable risk (PAR), population attributable risk percent (PARP) ▪Lost to followup bias（二）单选题（选择一个最佳答案）1. In cohort studies of the role of a suspected factor in the etiology of a disease, it isessential that: Da.There be equal numbers of persons in both study groupsb.At the beginning of the study, those with the disease and those without the diseasehave equal risks of having the factorc.The study group with the factor and the study group without the factor berepresentative of the general populationd.The exposed and nonexposed groups under study be as similar as possible withregard to possible confounding factorse.Both b and c2. Which of the following is NOT an advantage of a prospective cohort study? Aa.It usually costs less than a case-control studyb.Precise measurement of exposure is possiblec.Incidence rates can be calculatedd.Recall bias is minimized compared with a case-control studye.Many disease outcomes can be studied simultaneously.3. Retrospective cohort studies are characterized by all of the following except: Ca.The study groups are exposed and nonexposedb.Incidence rates may be computedc.The required sample size is smaller than that needed for a prospective cohort studyd.The required sample size is similar to that needed for a prospective cohort studye.They are useful rare exposures4. A major problem resulting from the lack of randomization in a cohort study is: Aa.The possibility that a factor led to the exposure, rather than the exposure itself,might have cause the diseaseb.The possibility that a greater proportion of people in the study may have beenexposedc.The possibility that a smaller proportion of people in the study may have beenexposedd.That, without randomization, the study may take longer to carry oute.Planned crossover is more likely.5. In a cohort study, the advantage of starting by selecting a defined population for studybefore any of it members become exposed, rather that starting by selecting exposed and nonexposed individuals, is that: Ca.The study can be completed more rapidlyb. A number of outcomes can be studied simultaneouslyc. A number of exposures can be studied simultaneouslyd.The study will cost less to carry oute.a and d6. Classify each of the studies (6.1-6.7) described below as either aa.Trialb.Cohort study,c.Case-control studyd.Cross-sectional study, ore.Ecological study6.1 A study investigated the relation between prostate cancer and energy restriction duringchildhood by examining prostate cancer occurrence in 58,279 men aged 55-69. The authors found no evidence that energy restriction early in life decreased prostate cancer risk later in life. B6.2 A study compared tea consumption in heart disease patients and a series of non-cases todetermine if tea consumptions was protective. C6.3 Surgical patients were assigned to one of three groups. Group 1 received antibiotics 24hours prior to surgery, group 2 received antibiotics 2 hours prior to surgery, and group 3 received no antibiotics. Risks of post-operative were compared. A6.4 Researchers in Liverpool, England published a landmark study in which 66% of themothers who had given birth to infants with spinal cord malformations were folic acid deficient. In contrast, only 17% of the mothers who had normal babies were folic acid deficient. C6.5 The British Research Council completed a study in which some of the women in a groupwho had given birth to babies with neural tube defects in the past and who were once again pregnant were supplemented with folic acid. The investigators found that supplementation reduced the risk of having second neural tube defect baby by 70%. A 6.6 At the Mayo Clinic in Rochester, Minnesota, researchers followed 939 patients who hadbeen classified as either optimists or pessimists. After thirty years of study a greater percentage of optimists were alive than pessimists. B6.7 A population-based sample showed higher prevalence of diabetes in Hispanics whitesthan non-Hispanic whites. D3. 某研究对某一社区所有居民观察了20年，在测量某疾病在这20年内的发病危险性时应采用哪一测量指标？BＡ．RR; B. 累积发病率；Ｃ．发病密度；Ｄ．ＳＭＲ；Ｅ．期间患病率（三）多选题1. 双盲随机对照临床实验比前瞻性队列研究最主要减少了哪些偏偏倚？BCＡ．失访偏倚；Ｂ．混杂偏倚；Ｃ. 差异性信息偏倚；Ｄ．无差异性信息偏倚；Ｅ．领先时间偏倚2. 在糖尿病病因的队列研究中，下列哪些调查对象选取方法是正确的？ＢＡ．在有糖尿病者中选择有无某种暴露因素的两组Ｂ．在无糖尿病者中选择有无某种暴露的两组Ｃ．任选有无暴露两组Ｄ．任选有无糖尿病两组Ｅ．从适龄人群中随机抽样3. 与病例对照研究相比，回顾性队列研究减少了哪些偏倚？ＡＢＡ．选择偏倚；Ｂ．回忆偏倚；Ｃ．观察者偏倚；Ｄ．混杂偏倚；Ｅ．失访偏倚3. 与病例对照研究相比，队列研究的优点有哪些？ＢＣＡ．能够研究稀有疾病Ｂ．能够研究稀有病因Ｃ．较直接地验证因果关联Ｄ．研究结果更能外推到全人群Ｅ．减少了过度匹配的问题(四) 简答题1. 回顾性队列研究与病例对照研究有何区别和联系?2. 前瞻性队列研究与回顾性队列研究相比，主要减少了哪些偏倚，为什么？信息偏倚：前瞻性研究中对暴露、结局的测量更为可靠混杂偏倚：前瞻性研究中往往测量了混杂因素或测量的可靠性比回顾性研究要好3. 流行病学实验研究的证据强度高于队列研究，主要是因为控制了什么偏倚？通过什么手段控制的？混杂偏倚：随机信息偏倚：盲法4. 前瞻性队列研究与病例对照相比主要控制了哪些偏倚？信息偏倚：对暴露的测定更为可靠或减少了回忆偏倚混杂偏倚：前瞻性研究中往往测量了混杂因素或测量的可靠性比病例对照研究要好选择偏倚：无新发和现患病例偏倚5. 前瞻性队列研究与其它研究设计（如病例—对照研究、横断面研究、非随机对照实验研究、随机对照实验研究等）在特征、偏倚、证据强度、优缺点等方面的比较。