F1,F2双语班流病

---○---○------○---○---………… 评卷密封线 ……………… 密封线内不要答题，密封线外不准填写考生信息，违者考试成绩按0分处理 ……………… 评卷密封线 ………… 中南大学考试试卷 2008 ~2009年 1 学期 流行病学 课程 时间90分钟 32学时， 2 学分，开卷，总分70分，占总评成绩100%一、Explanation:（4 point each ） 1. Case control study ：是以现在确诊的患有某种特定疾病的病人为病例，以不患有该病但具有可比性的个体作为对照，通过询问，实验室检查或复查病史，搜集既往各种可能的危险因素的暴露史，测量并比较病例组与对照组中各因素的暴露比例，经统计学检验，若两组差别有意义，则可认为因素与疾病之间存在统计学上的关联，在评估了各种偏倚对研究结果的影响之后，再借助病因推断技术，推断出某个或某些暴露因素是疾病的危险因素，而达到探索和检验疾病病因假说的目的。

2. Prevalence ：患病率，又称现患率，是指某特定时间内总人口中某病新旧病例所占的比例。

可按观察时间的不同分为时点患病率和期间患病率两种。

时点患病率=某一时点一定人群中现患某病新旧病例数/该时点人口数*K 期间患病率=某观察期间一定人群中现患有某病的新旧病例数/同期的平均人口数*K K=100%，1000‰或10000/万…. 3.Clinical trial ：临床试验（1分）：以病人为研究对象，目的是评价某种疾病的疗法或发现预防疾病结局如死亡或残疾的方法。

(1分) 临床试验的研究对象必须必须被诊断为患有所研究疾病并且诊断后很快进入研究，以便及时地安排治疗。

（1分）临床试验应当遵循随机、对照、双盲的原则。

(1分) 4. Randomization ：在实验研究中，随机化是一项极为重要的原则，通过随机化分组，使每个研究对象都有同等的机会被分配到各组去，以平衡实验组和对照组已知和未知的混杂因素，从而提高两组的可比性，使研究结论更加可靠。

常用的随机化分组的方法有三种，简单随机分组，分层随机分组，整群随机分组 5 Relative risk ：相对危险度（2’）也叫危险比或率比，是反映暴露与发病（死亡）关联强度的最有用的指标。

（1’） RR= 暴露组的率/ 非暴露组的率。

（1’）RR 表明暴露组发病或死亡的危险是非暴露组的多少倍。

（1’）RR 值越大，表明暴露的效应越大，暴露与结局关联的强度越大。

（1’）2.Read the following question carefully and chooses the best answer by circlethe corresponding letter.（2 point each）1) What is the best descriptor of the likelihood over 10 years than an initially unaffected person will develop hypertension? AA Incidence rateB RiskC Case fatalityD SensitivityE Specificity2) What is the best descriptor of proportion of person who have hypertension in a community residents. EA EpidemicB Incidence rateC RiskD Case fatalityE PrevalenceThe results of a study of the incidence of pulmonary tuberculosis in a village in India are given in the table below, all individual in the village were examined during two surveys made two years apart, and the number of the new cases was used to determine the incidence.Category of household at first survey Number of person Number of new casesWith culture positive case 500 10Without culture positive case 10000 103）What is the incidence of new cases per 1000 person-years in households that had a culture positive case during the first survey? DA 0.02B 0.01C 1.0D 10E 204 ）What is the incidence of new cases per 1000 person-years in households that did not have a culture positive case during the first survey? CA 0.001B 0.1C 0.5D 1.0E 5.05 ）What is the relative risk of acquiring tuberculosis in households with a culture-positive case compared to households without tuberculosis? 20A 0.001B 0.1C 0.5D 1.0E 5.06) is the percentage of persons with a positive test result who actually have the disease of interest. EA +PVB +LRC -PVD SpecificityE Sensitivity7）The main benefit of a randomized controlled trial (RCT) compared to all other epidemiology study design is that the RCT: DA is prospective thereby eliminating the need for historical dataB has better external validityC guarantees that confounding bias will not occurD tends to equally distribute into the study arms characteristics which may be independent risk factors for the outcome of interestE tends to avoid random misclassification of the outcome of interest8）A new test A (DT-A) is intended to be used in health care practice for the screening of disease D. In order to assess its performance, DT-A is tested on 83 subjects, out of those persons 46 are shown to be diseased and 37 are disease-free, using the currently best available diagnostic test B (DT-B). For the specific cut-points of DT-A, 43 persons are tested positive of which composed 41 patients and 2 non-patients. Consider DT-B as gold standard, the sensitivity of DT-A is: CA. 95.34%B. 93.48%C. 89.13% D 94.59% E. 87.50%---○---○------○---○---………… 评卷密封线 ……………… 密封线内不要答题，密封线外不准填写考生信息，违者考试成绩按0分处理 ……………… 评卷密封线 ………… 9） Researchers conduct a randomized controlled trial to determine if Med A reduces post-operative pain more than Med B. The primary purpose of double blinding this trial is to avoid: E A. recall bias B. selection bias C. surveillance bias D. non-random (differential) misclassification of exposure status E. non-random (differential) misclassification of outcome status 10. A screening program for thyroid cancer detected a high proportion of those with slowly progressive disease whose outcome was not altered by the screening program. Which of the following screening issues is illustrated? B A.Lead-time bias B. length bias C. Higher frequency of detection occurs on initial compared to subsequent screening. D. Error due to the technique used to obtain the test sample E. Self-selection bias 3. Give the brief answer (10 point). 1 What ’s the difference between case control study and cohort study? (8 points) 答：相同点：病例对照研究和队列研究都属于分析性流行病学研究，都能检验病因假设，都需要进行分组。