Epi Quizzes Exam 2

Which of the following would create a potential problem in a cohort study? Select one: a. Different diagnostic criteria were applied in the exposed and unexposed groups b. Data is extracted from existing medical records c. Both exposed and unexposed group were followed up for the same period of time d. Data is comparable and unbiased

A

A 66-year-old man with hormone-refractory prostate cancer comes into your office for a follow-up visit. You suggest he consider participating in a clinical trial, which is designed to compare 2 different chemotherapy regimens in men with this disease. The trial is being conducted at cancer centers throughout the country and will enroll about 400 patients. What is the most likely phase trial of this drug? Select one: a. Phase 0 trial b. Phase I trial c. Phase II trial d. Phase III trial e. Phase IV trial

D

In a randomized clinical study, 25% of the subjects in the intervention group experienced cure from the disease of interest in the study period, whereas in the same period 20% of the subjects in the control group were cured. Calculate the number needed to treat for the study.

20

11 individuals with similar demographic characteristics, but who did not have nasopharyngeal cancer were then recruited. The researchers subsequently interviewed all of these participants to determine whether they remembered smelling fumes at work. In conducting this pilot study, researchers employed the epidemiologic designs of: Select one: a. Case-control study b. Cross-sectional study c. Cohort Study d. Controlled Clinical Study e. Case series study

A

A 39-year-old female breast cancer patient comes into your office to discuss a new form of treatment. She underwent lumpectomy and radiation therapy 6 months ago but is concerned about her cancer returning. She has been actively searching for different treatment options and has learned about a Phase II clinical trial of a new breast cancer vaccine. She wants to know what a 'Phase II' trial is. What would you explain to her about a Phase II trial and what it determines? Select one: a. If the new treatment is safe b. The best way to give the new treatment c. If the new treatment is efficacious d. If the new treatment is more effective than current treatments e. If the new treatment is safer than current treatments

A

Based on the "Factors associated with mortality in Scottish patients receiving methadone in primary care: retrospective cohort study", the 2378 people who were prescribed and dispensed liquid methadone between January 1993 and February 2004 can also be called: Select one: a. Cohort b. Unexposed group c. Controls d. Cases e. Exposed group

A

What is meant by "randomization" in clinical trials? Select one: a. Selection of subjects at random b. Method of allocating treatment such that each subject has equal change of receiving any of the possible treatments c. Regression to the mean in common in clinical trial d. Randomization means generating random numbers

B

How does the strategy for a case-control study differ from that of a cohort study? Select one: a. Case-control studies are retrospective, while cohort studies are always prospective b. Randomization can be used in a cohort study, but cant be used in a case-control study c. In case-control studies subjects are selected and grouped based on their disease status, but in cohort studies subjects are selected and grouped based on exposure status d. The goal of a cohort study is to test an association, but case-control studies just document the frequency of risk factors

C

___________ error occurs when the list of potential survey participants does not include all elements of the population that one wishes to study. Select one: a. Measurement error b. Non-response error c. Coverage error d. Sampling error

C

What are the factors that can affect sample size calculation in a RCT? Select one: a. Type I error b. Type II error c. Treatment effect size d. Control group response rate and likely variability in the target group population e. All of the above

E

Which of the following types of data can be collected with surveys? Select one: a. Knowledge data b. Attitudinal data c. Behavioral data d. cause and effect data e. a through c f. all of the above

E

Children aged six to nine months were randomly assigned to receive either placebo or a beverage containing a zinc supplement. Morbidity data were collected daily, and focused on the presence of diarrhea and/or respiratory infections. What is the best description of this type of study? Select one: a. A clinical trial b. A cohort study c. A case control study d. A cross sectional study e. A case series

A

In a cohort of gym members, the patrons were classified as machine-users (n=1000) and free-weight users (n=425), and followed for 3 years. 85 machine-users and 15 free-weight users became injured in the 3 years. Calculate the relative risk of injury among machine users compared to free weight users. What is the absolute risk reduction? Select one: a. 0.05 b. 2.0 c. 0.5 d. 20

A

When is a cohort study warranted? Select one: a. When RCT is unethical b. For disease with long latency periods c. When multiple exposures are to be studied d. For rare diseases

A

________________ can occur if researchers fail to collect data from each member of the sample. Select one: a. Non-response error b. Coverage error c. Sampling error d. Measurement error

A

A recent study was conducted to assess a new drug that prevents wound healing but which is also designed to reduce the incidence of endophthalmitis. The incidence of endophthalmitis in this study was found to be 12% in 25 patients given the new drug and 20% for patients given the Mitomycin C. What is the relative risk of endophthalmitis in patients receiving the new drug compared to Mitomycin C. Select one: a. 1.67 b. 0.6 c. 1.25 d. 0.8

B

Cross-sectional studies can gather a large amount of data relatively quickly. What is an advantage of longitudinal study over cross-sectional study design? Select one: a. People can remember how they responded previously b. They provide a better basis than cross-sectional studies for making suggestions about cause and effect c. They are easier to run than cross-sectional studies d. People who don't really want to take part drop out of them part way through

B

It would be of interest to know whether or not mildly elevated levels of radon in homes causes any long-term adverse health events such as lung cancer or heart disease. Which of the following would be best to use to obtain this information? Select one: a. Cross sectional study b. Case-control study c. Cohort study d. Clinical trial

B

Lost to follow up bias is a significant disadvantage of the case-control study design. Select one: a. True b. False

B

Prospective and Retrospective are types of : Select one: a. Randomized clinical trial b. Cohort study c. Case control study d. Case series

B

What was the overall response rate in the Borrego et al New Mexico Pharmacists' Knowledge, Attitudes, and Beliefs Toward Prescribing Oral Emergency Contraception 2006 mail survey? Select one: a. 38% b. 40% c. 85% d. 100%

B

Which statement about blinding in an intervention study is NOT correct? Select one: a. The purpose of blinding is to reduce bias in determining the outcome b. The purpose of blinding is to reduce confounding (confounding is when the study results are distorted by some factor other than the variable(s) being studied.) c. In a double blinded study, neither the subject nor the investigators know which treatment the subject is receiving d. Placebos can help in blinding

B

_____________ can occur if the response by the respondents is different than the actual or true answer. Select one: a. Non-response error b. Measurement error c. Coverage error d. Sampling error

B

A group of investigators selected 135 subjects with a diagnosis of Alzheimer's Disease (AD) and 145 subjects without a diagnosis of AD or other dementias. After enrolling these subjects, the investigators interviewed the patients and their family members, and they searched their medical records for evidence of long-term use of non-steroidal anti-inflammatory drugs (NSAIDs). As of result of data collected during this study, the authors concluded that those patients with long-term exposure to NSAIDs were less likely to have AD (odds ratio 0.7, 95% confidence interval 0.58 - 0.94). What is the best description of this type of study? Select one: a. A clinical trial b. A cohort study c. A case-control study d. A cross-sectional study e. A case series

C

Based on the "Hormone use and lung cancer incidence: the Rancho Bernardo cohort study", which of the following statement is true Select one: a. The women were followed up for 10 years b. The study is a retrospective cohort study c. The study did not find any association between hormone use and lung cancer incidence d. Although not statistically significant, post menopausal women on hormone therapy have lower risk of lung cancer when compared to younger women.

C

In a cohort study examining the association between smoking and lung cancer, suppose the relative risk was 10. How would you interpret the relative risk in words? Select one: a. There were 10 more cases of lung cancer in the smokers. b. Smokers had 10% more lung cancers compared to non-smokers. c. Smokers had 10 times the risk of lung cancer compared to non-smokers. d. 17% of the lung cancers in smokers were due to smoking

C

In cross-sectional studies the exposure and outcome are measured at the sample point in time, hence Select one: a. We can establish causality from the data collected b. The study meets the temporality requirement c. we can determine prevalence of an exposure and outcome at the point in time d. cross sectional studies are non-observational in nature.

C

Is Low Dose Aspirin Beneficial? The Physician's Health Study was conducted to test the hypothesis that 325 mg. of aspirin taken every other day would reduce mortality from cardiovascular disease (N. Engl. J. Med. 320:1238, 1989). Male physicians 40 to 84 years of age living in the US in 1980 were eligible to participate. Physicians were excluded if they had a personal history of myocardial infarction, stroke or transient ischemic attack, cancer, current gout, liver, renal or peptic ulcer disease, contraindication to aspirin consumption, current use of aspirin, platelet-active drugs or non-steroidal anti-inflammatory agents, intolerance to aspirin, or inability to comply with the protocol. Eligible subjects who met the inclusion criteria and who successfully completed a run-in phase were randomly assigned to receive aspirin or a placebo. Eventually 22,071 physicians were enrolled 11,037 were assigned to aspirin, and 11,034 were assigned to placebo. The agents (aspirin and placebo) were identical in appearance and were mailed to the subjects. The recipient's treatment was coded, and neither the subject nor the investigators knew which treatment group a given subject was in. Table 1 below shows the frequency of some risk factors of the subjects at the beginning of the study (baseline). RR is the relative risk of having the risk factor, comparing those who received aspirin to those who received placebo. The p-values that were computed were based on a comparison of the frequency of having the risk factor (or not) among the two treatment groups. Which of the following is an appropriate conclusion that can be drawn from these data>? Select one: a. Aspirin did not reduce the risk of diabetes b. The sample size was too small c. Based on the data, randomization appears to be successful d. The frequency of diabetes difference significantly between the two groups

C

What is "blinding" and what is its purpose? Select one: a. Blinding means you begin with null hypothesis, and base your conclusions totally based on statistical analysis of the data without any preconceived ideas b. Blinding refers to equipoise, ie uncertainty regarding whether a new treatment is effective. c. Blinding means that the subjects and/or investigators do not know which treatment group the subjects is in. The purpose is to prevent bias in assessing the outcome. d. Blinding occurs when the results totally disagree with previously published studies. Its purpose is to cause a re-evaluation of the data.

C

What is the main reason why it is important to use precise, specific criteria for what constitutes a "case", ie in defining the outcome? Select one: a. To limit the number of subjects in the study b. To avoid selection bias c. To avoid misclassification with respect to the outcome d. To avoid interviewer bias

C

Which of the following best describes non-inferiority trials? Select one: a. Is drug A better than drug B b. Is drug A just as good and as drug B c. Is drug A no worse than drug B d. none of the above

C

Which of the following measures of association can be calculated using a case-control study? Select one: a. Attributable risk b. Relative risk c. Odds ratio d. All of the above

C

Which of the following statement regarding the selection of exposed subjects in a cohort study is true? Select one: a. For common risk factors use a special exposure cohort b. subjects should be free of the exposure c. for rare/unusual factors/exposure, a special cohort should be used d. Participants who are selection should always be from the same city

C

Which of the study designs best describes the following statement. "A group of people is identified and assembled in the past on the basis of existing records and is "followed" up to present time. Select one: a. Cross sectional study b. Case-control study c. Retrospective cohort study d. Prospective cohort study

C

A study comparing the effectiveness of buprenorphine compared to methadone for treatment of substance abuse disorder is being conducted. Buprenorphine is in an oral dosage form whereas methadone is dispensed as a liquid (suspension). As a lead research designer, your goal is to design a study to compare these two therapies. What type of RCT would best compare these two treatments? Select one: a. Placebo controlled randomized clinical trial b. Placebo controlled double blinded randomized clinical trial c. Active treatment controlled double blinded randomized clinical trial d. Active treatment controlled double dummy double blinded randomized clinical trial

D

All are true statements about randomized control trial except? Select one: a. Baseline characteristics of intervention and control group must be similar b. Investigator bias can be minimized by double blinding c. The sample size depends on the hypothesis being tested d. Drop outs should always be excluded from the analysis

D

What problem arises when the compliance of subject is poor in a randomized intervention study? Select one: a. Confounding will be introduced b. The results will be biased away from the null c. The effectiveness of the blinding will be jeopardized d. If compliance is poor, the two groups (treatment vs controls) will become more alike and the ability to detect true differences in outcomes is diminished.

D

You read an article in a journal which reported the results of a study that sought to assess knowledge related to blood glucose self-monitoring among Hispanic, type II diabetes patients with limited English proficiency. The study consisted of a 35-item, self-administered questionnaire written at the 5th grade English level. Which of the following potential survey research errors would you be most concerned with as you read the results of this study. Select one: a. non-response error b. coverage error c. sampling error d. measurement error e. none of the above

D

________ can occur when researcher surveys only a subset of all possible subjects within the population of interest leading to a discrepancy between the true value of population parameter and the sample estimate of that parameter. Select one: a. Measurement error b. Non-response error c. Coverage error d. Sampling error

D

According to the required reading: Harrison DL, Draugalis JR. Evaluating the results of mail survey research J Am Pharm Assoc 1997, which of the following aspects are important in the evaluation of mail survey research? Select one: a. generalizability of the survey results b. The four sources of error that may operate in any survey c. validity assessment which involves the calculation of Cronbach's alpha d. response rates less than 100% e. a and b only f. all of the above

E

Based on the "Factors associated with mortality in Scottish patients receiving methadone in primary care: retrospective cohort study". What were the factors associated with drug dependent death? Select one: a. Overuse of methadone b. history of psychiatric admission c. Increasing comorbidity measured as charlson index >=3 d. History of prescription of benzodiazepines e. b and d Correct f. a and c g. all of the above

E

In the "Hormone use and lung cancer incidence: the Rancho Bernardo cohort study", how was the exposure to hormone use established Select one: a. Data extraction from electronic medical records b. self reported hormone use "are you taking oral contraceptives..... to regulate periods" c. Claim database d. self reported data validated by examination of pills and prescriptions brought to the clinic e. b and d f. a and c g. all of the above

E

The major purpose of randomization in clinical trials is to Select one: a. Facilitate double blinding b. Help ensure that the study subjects are representative of general population c. Ensure that the groups are comparable on baseline characteristics d. Reduce selection bias in allocation of treatment e. A and B f. C and D g. All of the above

F

What are the major disadvantages of a cohort study? Select one: a. Can estimate the incidence of disease and risk b. Can be very expensive c. There is a chance of loss to follow up bias d. Can study multiple outcomes because of a single factor e. All of the above f. b and c only g. b, c and d

F

In a case-control study, one can calculate either a risk ratio or an odds ratio. Select one: True False

False

Which of the following are the advantages to case-control studies? Select one: a. They tend to be less expensive and more efficient than prospective studies b. They are feasible for rare diseases c. They allow you to study multiple outcomes of a single risk factor d. They are good for diseases that have a long latency period e. a and b only f. a, b, and c g. a, b, and d Correct h. all of the above

G

The primary principle to be followed in identifying an appropriate control group is that control groups should be a sample of the population that gave rise to the cases, and if a member of the control group had had the disease being studied, they would have been identified as a potential case for the study. Select one: True False

True