Medicine Expert Q&A

The following is a measure of the strength of association,typically used in case-control studies to measure the association between exposure and disease:

A) Incidence rate
B) Population attributable fraction
C) Attributable fraction
D) Prevalence
E) Odds ratio

Which of the following measures represents the absolute risk of getting a disease?

A) Prevalence
B) Odds ratio
C) Risk ratio
D) Incidence
E) Risk difference

Which of the following statements is the most accurate description of the attributable risk (deaths per 100,000) of coronary heart disease for smokers in this study? Use the following information: Lung Cancer and Coronary Health Disease Mortality by Smoking Status
$$\begin{array}{r}\text{ Age-adjusted death rates per }100,000\\ \begin{array}{lll}& \text{ Smokers }& \text{ Nonsmokers }\\ \text{ Lung cancer }& 150& 70\\ \text{ Coronary heart disease }& 700& 300\end{array}\end{array}$$ [Modified from Doll R,Peto R.Mortality in relation to smoking: 20 years' observations on male British doctors.Br Med J.1976;2(6051) :1525-1536.]

A) The attributable risk of coronary heart disease deaths is 700 deaths per 100,000.
B) The attributable risk of coronary heart disease deaths is 400 deaths per 100,000.
C) Attributable risk cannot be used as an indicator of the disease burden reduction that could be achieved if the risk factor eliminated.
D) The risk of coronary heart disease deaths among smokers is 70 per 100,000.
E) The risk of coronary heart disease deaths among nonsmokers is 30 per 100,000.

The population of Oriol City in June 2018 was 612,437.According to the Oriol City's health department,there were 329 new cases of Raven's disease during 2018.Counting those new cases,by December 31 it was estimated that there were 6580 persons with Raven's disease in Oriol City.What was the incidence rate of Raven's disease in 2018?

A) 26 per 100,000 population
B) 33 per 100,000 population
C) 54 per 100,000 population
D) 1074 per 100,000 population
E) 5000 per 100,000 population

Epidemiologists tried to examine the distribution of multimorbidity,and of comorbidity of physical and mental health disorders,in relation to age and socioeconomic deprivation.They extracted data on 40 morbidities from a database of 1,751,841 people registered with 314 medical practices in Scotland as of March 2007.They analyzed the data according to the number of morbidities,disorder type (physical or mental) ,sex,age,and socioeconomic status.They defined multimorbidity as the presence of two or more disorders.[From Barnett K,Mercer SW,Norbury M,et al.Epidemiology of multimorbidity and implications for health care,research,and medical education.Lancet.2012;380(9836) :37-43.] What is the proper classification for this study?

A) Cross-sectional study
B) Prospective cohort study
C) Case-control study
D) Randomized trial
E) Case report

Calculate the age-adjusted death rate from disease X in cities A and B by the direct method,using the total of both cities as the standard population.What is the age-adjusted death rate from disease X for City B? Use the following table to answer the question. Number of Residents and Deaths From Disease X by Age Group in City A and City B
\begin{array}{|c|c|c|}\hline\quad\quad\quad\quad\quad\text{} &\quad\quad\quad\quad\quad\quad\quad\text{City A} \quad\quad\quad\quad\quad\quad\ & \quad\quad\quad\quad\quad\quad\quad\text{City B}\quad\quad\quad\quad\quad\quad\\end{array}
$\begin{array}{lllll}\text{ Age group }& \text{ No. of residents }& \begin{array}{l}\text{ No. of deaths }\\ \text{ from disease X }\end{array}& \text{ No. of residents }& \begin{array}{l}\text{ No. of deaths }\\ \text{ from disease X }\end{array}\\ \text{ Age }<65& 3,000& 30& 6,000& 60\\ \text{ Age }>65& 6,000& 450& 3,000& 225\end{array}$

A) 53 deaths/1,000 people
B) 32 deaths/1,000 people
C) 10 deaths/1,000 people
D) 75 deaths/1,000 people
E) 43 deaths/1,000 people

Which of the following statements is not evidence suggesting Exposure A as a causative agent on Disease X?

A) Exposure A is clearly linked to mediator M. Approximately 11% of mediator M patients will go on to have Disease X over a 10-year period.
B) Many of the observations regarding Exposure A and Disease X have been replicated repeatedly.
C) Prevalence of Exposure A in patients with Disease X is 90% to 100%.
D) Eradication of Exposure A heals Disease X at the same rate as other treatment of choice.
E) None of above

In a cohort study of smoking and myocardial infarction in City A,the number of myocardial infarctions were 250 cases among 7,000 smokers and the number of myocardial infarctions were 150 cases among 20,000 nonsmokers.What is the attributable risk (risk difference) of smoking?

A) 2.8 per 1,000
B) 3.6 per 1,000
C) 7.5 per 1,000
D) 28.2 per 1,000
E) 35.7 per 1,000

Two infectious disease epidemiologists want to investigate a new laboratory test that identifies tuberculosis (TB) infections.Dr.Merritt uses the standard test,which has a sensitivity of 80% and a specificity of 90%.Dr.Foundry uses the new laboratory test,which is 90% sensitive and 99% specific.In City A,it is known that 100 of 1,000 people have TB infections.What is the positive predictive value of the standard test in City A?

A) 10%
B) 47%
C) 53%
D) 80%
E) 90%

Investigators think that income might be a confounder in the relationship between Hispanic ethnicity and cardiovascular disease.They conduct a case-control study,and they match cases and controls based on income.They find that Hispanics are more likely to have cardiovascular disease as compared with non-Hispanics.What is the measure of association used in such study?

A) Risk ratio
B) Relative risk
C) Incidence rate ratio
D) Attack rate
E) Odds ratio

A politician asks an epidemiologist how many cases of coronary heart disease can be prevented if they manage to eliminate the exposure to smoking in city A.The epidemiologists explain that,if they eliminate smoking,they could prevent 22% cases of coronary heart disease.What measure of association was used to answer this question?

A) Population attributable risk
B) Odds ratio
C) Relative risk
D) Incidence rate
E) Risk ratio

Which of the following statements is the most accurate characteristic of the nested case-control study?

A) A control who is selected early in the study could later develop the disease but cannot be a case in the same study.
B) In nested case-control studies, controls are a sample of individuals who are at risk for the disease at the time each case of disease develops.
C) Controls are randomly chosen from the defined cohort with which the study began.
D) The problems of possible recall bias from conventional case-control studies still remains.
E) Nested case-control studies are often less economical to conduct.

The Baltimore Longitudinal Study of Aging (BLSA) is a research study of normative aging started in the 1950s.Volunteers,free of chronic conditions,are recruited and followed every 4,2,or 1 year(s) until their death.What type of study design is this?

A) Cross-sectional
B) Ecologic
C) Randomized trial
D) Retrospective cohort
E) Prospective cohort

Temporal relationship is a necessary criterion to establish causality.Which of the following epidemiologic study design allows to evaluate temporal relationship?

A) Cross-sectional
B) Case-control
C) Transversal
D) Cohort
E) Literature review

What is the age-specific mortality rate from disease X in City B for age younger than 65? Use the following table to answer the question. Number of Residents and Deaths From Disease X by Age Group in City A and City B
\begin{array}{|c|c|c|}\hline\quad\quad\quad\quad\quad\text{} &\quad\quad\quad\quad\quad\quad\quad\text{City A} \quad\quad\quad\quad\quad\quad\ & \quad\quad\quad\quad\quad\quad\quad\text{City B}\quad\quad\quad\quad\quad\quad\\end{array}
$\begin{array}{lllll}\text{ Age group }& \text{ No. of residents }& \begin{array}{l}\text{ No. of deaths }\\ \text{ from disease X }\end{array}& \text{ No. of residents }& \begin{array}{l}\text{ No. of deaths }\\ \text{ from disease X }\end{array}\\ \text{ Age }<65& 3,000& 30& 6,000& 60\\ \text{ Age }>65& 6,000& 450& 3,000& 225\end{array}$

A) 53 deaths/1,000 people
B) 32 deaths/1,000 people
C) 10 deaths/1,000 people
D) 75 deaths/1,000 people
E) 43 deaths/1,000 people

Which of the following statements is the most accurate characteristic of cohort studies?

A) It is an efficient study designs for studying rare disease.
B) The temporality of the exposure preceding the outcome is hard to determine.
C) The incidence rate of disease in the exposure group is compared directly to the incidence rate of disease in the unexposed group.
D) The exposure and outcomes are captured at the same time.
E) The participants are randomly allocated to exposure and nonexposure categories.

Investigators think that income might be a confounder in the relationship between Hispanic ethnicity and cardiovascular disease.They conduct a case-control study and they match cases and controls based on income.They find that Hispanics are more likely to have cardiovascular disease as compared with non-Hispanics.What would you conclude about income as a potential confounder in this association?

A) Income is a confounder.
B) Income is not a confounder.
C) Income is an effect modifier.
D) Income is not associated with cardiovascular disease.
E) Income is not associated with ethnicity.

The mayor of Baby City is interested in comparing the infant mortality rate (infants are defined as babies younger than the age of 12 months) of Baby City with the infant mortality rate of Adult City.He argues that the age distributions of these cities are very different and therefore asks you to calculate the age-adjusted infant mortality rate.What is the best approach?

A) Use direct adjustment.
B) Use indirect adjustment.
C) Calculate the standardized mortality ratio.
D) Explain that no age adjustment is needed when comparing with age-specific mortality rates.
E) Use the World Health Organization standard population to calculate an adjusted rate.

In which of the following study designs is possible to calculate incidence rate?

A) Cross-sectional
B) Case-control
C) Cohort
D) Case-series
E) Report of a case

Researchers wanted to provide additional support for a causal association between human papillomavirus (HPV) and oropharyngeal cancers.They performed an epidemiologic study of 100 patients with newly diagnosed oropharyngeal cancer and 200 control patients without cancer to evaluate associations between HPV infection and oropharyngeal cancer.[D'souza G,Kreimer AR,Viscidi R,et al.A study of human papillomavirus and oropharyngeal cancer.N Engl J Med.2007;356(19) :1944-1956.] What kind of study design is this?

A) Retrospective cohort study
B) Prospective cohort study
C) Case-control study
D) Randomized trial
E) Case report