Epidemiology Multiple Choice Questions and Answers 100% Correct

A case-control study, if properly designed, should provide the same answer about the exposure-disease relationship as a cohort study, however case-control studies are generally more vulnerable to all except which of the following challenges: - ANSWER-Difficulty measuring past exposures (ANSWER) Difficulties in rare disease diagnosis Recall bias Difficulties in choosing representative cases and controls A confounder is - ANSWER-a factor associated with the outcome and associated with the exposure, but not on the causal pathway True or False? If an effect is real but the magnitude of the effect is different for different groups of individuals, effect modification is likely present. - ANSWER-true A national survey of asthma conducted on May 1, 2012, obtained the following results for the state of Oklahoma: X = The number of residents with asthma; Y = The population of the state on June 30, 2012, and all members of the population were considered at risk; Z = The number of new cases of asthma diagnosed during 2012. The point prevalence of asthma (proportion) on May 1, 2012, would be expressed as: - ANSWER-X/Y Of the different epidemiological study designs, the ecological design is considered the weakest because - ANSWER-Across a population, individuals with risk factors are not necessarily the same individuals who contract the disease True or False? A relative risk of less than 1 means that there is no association between exposure and outcome. - ANSWER-False Cohort study is to risk ratio as: - ANSWER-case-control study is to odds ratio. Examples of purely observational epidemiologic studies do not usually include: - ANSWER-experimental studies In a cohort study, epidemiologists usually begin with an exposed group, then assemble a nonexposed group for comparison. This approach is good for - ANSWER-Rare exposures and common diseases What is the main reason why randomized clinical trials, the gold standard for evidence in medicine, are not commonly used in environmental and occupational epidemiology - ANSWER-It would be unethical to randomize participants into exposed and unexposed groups Which of the following statements is true about cohort studies? - ANSWER-All statements are true: Subjects are classified according to their exposure. They are a type of longitudinal design. They may be either prospective or retrospective. The measure of association is called relative risk. True or False? An ecologic study is one that examines a group as the unit of analysis. - ANSWER-True A national survey of asthma conducted on May 1, 2012, obtained the following results for the state of Oklahoma: X = The number of residents with asthma; Y = The population of the state on June 30, 2012, and all members of the population were considered at risk; Z = The number of new cases of asthma diagnosed during 2012. The incidence rate of asthma during 2012 (per 100,000) would be expressed as - ANSWER-(Z/Y) × 100,000 The limitations of environmental epidemiology include the fact that - ANSWER-All statements are limitations of environmental epidemiology: Accurate assessment of exposure is difficult. Environmentally associated diseases often have low incidence and prevalence. Long latency periods often occur between initial exposures and disease outcomes. The effects of exposures are often non-specific. True or False? Cross-sectional studies may be used to formulate hypotheses that can be followed up in analytic studies. - ANSWER-True A cross-sectional study, if properly designed, should provide results that can be confirmed by cohort or case-control studies, however cross-sectional studies generally face the following major challenge (pick one) - ANSWER-Difficult to determine whether the exposure or outcome came first Those members of the population who are capable of developing a disease or condition are known as: - ANSWER-the population at risk Which of the following observational designs is used for hypothesis testing? - ANSWER-Cohort studies