流行病学英文讨论课题目3

2.2 For each of the following features, indicate whether it belongs to A for cohort study or B for case-control study
① ② ③ ④
⑤
⑥ ⑦ ⑧ ⑨ ⑩
best for common outcomes good for rare outcomes relatively inexpensive outcome is measured after exposure yields true incidence rates and relative risks smaller numbers required may uncover unanticipated associations with outcome takes a long time to complete controls are selected on the basis of not having the outcome outcome is measured before exposure
Discussion 2
Clinical Trials Cohort study Case Control study
Part 1 clinical trial
1.1 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: A. recall bias B. selection bias C. confounding bias D. non-random (differential) misclassification of exposure status E. non-random (differential) misclassification of outcome status
1.2 The main benefit of a randomized controlled trial (RCT) compared to all other epidemiologic study design is that the RCT: A. is prospective thereby eliminating the need for historical data B. has better external validity C. guarantees that confounding bias will not occur D. tends to equally distribute into the study arms characteristics which may be independent risk factors for the outcome of interest E. tends to avoid random misclassification of the outcome of interest
2.13 The researchers only studied male Army soldiers. Select the best statement: A) The failure to study female Army soldiers is a possible source of confounding bias. B) Recall bias may have led to misclassification of exposure status.
1.4 Fill the blank with ”yes ”or “no”
Knowledge of Treatment Assignment Blinding
None
Patient
Investigator
Single Double
Results of the coronary artery disease (CAD) Therapy Trial Concerning the Risk of Developing MI
1.3
is a method that maximizes the probability that the two groups will be similar in background characteristics that may influence either the response to therapy or the primary outcome measure. A. blinding B. Randomization C. diagnostic criteria D. placebo-controlled trial.
Researchers investigated that 100 patients with bladder cancer and 600 patients without bladder cancer. 20 of bladder cancer patients smoke, while 40 of without bladder cancer patients smoke cigarettes. 2. 5 What is the study design? Calculate the appropriate measure of association for developing bladder cancer in smokers vs. non-smokers. 2.6 Interpret the measure of association you calculated in question.
④
2.4 Select the correct statement:





a.) The attributable risk is the excess risk of disease in the exposed compared to the non-exposed during a defined period of time. b.) The attributable risk is a ratio of the disease risk in the exposed compared to the non-exposed during a defined period of time. c.) The attributable risk is a ratio of the disease risk in the nonexposed compared to the exposed during a defined period of time. d.) The attributable risk is the prevalence of disease in the exposed minus the prevalence of disease in the non-exposed. e.) The attributable risk is the disease risk in a defined group at a specific point in time.


The researchers used military records, which were accurately maintained by unit leaders, not the subjects themselves, to establish if each subject did or did not serve in the Gulf War. The study concluded that Army soldiers who served in the Gulf War had 50% more risk of having subsequent neurological disease vs. those who did not serve in the Gulf War.
Part 2
Cohort study Case Control study
2.1 when the incidence rate of the disease is rare, what kind of study is most suitable to explore the underlying etiology? A Prospective study B case- control C descriptive study D clinical trial
Treatment
myocardial infarction
Yes
Medicine A
91
Medicine B
23
Total
114
No
287
325
612
Total
378
348wk.baidu.com
726



1.5 Calculate the risk of developing MI in each treatment group. 1.6 What is the percentage of risk of MI that would be avoided if Medicine B were used instead of Medicine A? 1.7 What is relative risk or rate ratio? How to explain its epidemiological significance?
2.3 Indicate next to each statement below whether you consider it to be TRUE, or FALSE
①
An advantage of cohort study compared to the case control study is that cohort studies can directly estimate risks. The temporal sequence of exposure and disease can be directly addressed in a cohort study as well as in a case control study.


In 1993 a case control study was conducted to assess a possible association between serving in the Gulf War in 1991 and the subsequent diagnosis of neurological diseases. Researchers compared the military records of 750 Army soldiers seen for neurological symptoms at Walter Reed Army Hospital in 1992 to 1500 Army soldiers seen at Walter Reed Hospital the same year for nonneurological symptoms.
②
③
A disadvantage of the cohort study compared to a case control study is that in a cohort study one cannot address multiple outcomes. A disadvantage of the cohort study compared to a case control study is that in a cohort study one needs to follow a large number of participants if the disease is rare.