Exam 1 Refresh
1. Which is the best reason to conduct a systematic review to make a strong case for a causal relationship?
A: In a systematic review, investigators ensure that their findings satisfy all of the Bradford Hill considerations for causal relationships.
B: Systematic reviews always analyze multiple randomized clinical trials.
C: In a systematic review, investigators collect data, in a systematic way, about all known patients with an emerging infectious disease.
D: Systematic reviews summarize original research following a scientifically-based plan that has been decided on in advance and made explicit at every step.
2. You are on the hospital s preventive services review team. You are deliberating about a plan to implement a screening program for abdominal aortic aneurysms (AAA). The proposal is to screen all people who have ever smoked tobacco for AAA with an ultrasound. Your hospital would need to provide the equipment, specialized personnel, and ensure access to specialist care for positive screens. Which type of study will be most useful in evaluating this plan?
A: Cross-sectional study measuring the causes of death of people with AAA
B: Cohort study of 20 participants with AAA who do not have surgical intervention
C: Systematic review of similar screening programs from multiple countries and health systems
D: RCT comparing two types of ultrasound techniques
1. D: Systematic reviews summarize original research following a scientifically-based plan that has been decided on in advance and made explicit at every step.
2. C: Systematic review of similar screening programs from multiple countries and health systems
A group of people is assembled, none of whom has experienced the outcome but all of whom can experience the outcome
What is a cohort study?
incidence in exposed persons/ incidence in nonexposed persons
(a/a+b)/(c/c+d)
What is relative risk?
Define the Difference between Observational and Experimental.
1. Investigators receive additional funding to conduct additional tests to understand more about high blood pressure in young people. They recruit 100 students from each year of the nursing, medical, and dental school programs. The students complete a 20-minute online survey and have lab testing completed at the student health center lab to evaluate their cardiometabolic markers. This new study is:
2.The investigators obtained additional funding to learn about medical and dental students as well. These two additional groups were also texted and asked how much they exercise each week and whether they currently have (or have ever been diagnosed with) high blood pressure. This new study is:
3.Decide which type of study is described by the scenario presented. A representative sample of first-year nursing students at UC Davis were texted a three-question survey. The survey asked how much they exercise each week, their family history of illness, and whether they currently have (or have ever been diagnosed with) high blood pressure.
1. 2. 3. Observational Cross-sectional
A study evaluated calorie needs in a pediatric ICU for children who are intubated (on a breathing machine). They found that on average, pediatric caloric needs were distributed normally by age, height and gender. Which of the following would best represent an ecologic fallacy?
A: Children will benefit from being fed based on their predicted caloric intake
B: Children will be harmed by being fed based on their predicted caloric intake
C: A given childಬs caloric intake can be determined from the study results
D: A given childಬs caloric intake cannot be determined from the study results
C: A given child's caloric intake can be determined from the study results
Fraction or proportion of a group of people initially free of the outcome of interest that develops the condition over a given period of time.
What is Incidence?
When a given sample, without bias, may misrepresent the situation in the population as a whole
What is Chance?
Randomization is ethical when there is no compelling reason to believe that either of the randomly allocated treatments is better than the other.
What is Equipoise?
A large study of estradiol levels in patients with XY chromosomes (assigned male at birth) reveals that the parameter is normally distributed with a mean of 30 picograms/mL and standard deviation of 5 picograms/mL. According to these results, 95% of estradiol observations in these patients lie between which of the following limits?
A: 25 and 35 picograms/mL
B: 25 and 40 picograms/mL
C: 20 and 40 picograms/mL
D: 15 and 45 picograms/mL
E: 10 and 50 picograms/mL
C: 20 and 40 picograms/mL
1. you are in a pediatric hematology oncology rotation and are rounding in the neonatal intensive care unit. You are discussing the early development of the immune system. You review branches of the immune system: passive, adaptive, and innate. These branches are examples of which type of variable?
2. Typically, absolute neutrophil counts (ANC) are 1,500 cells/microliter or higher. The normal range for ANC for neonates is 6,000 26,000 cells/microliter. Your patient s ANC is 800 cells/microliter. The ANC is an example of which type of variable?
3. The resident reports the ANC as indicative of moderate neutropenia. Neutropenia means low ANC and causes patients to be immunocompromised. Neutropenia is classified as follows: Mild: 1,000 5,999 cells/microliter Moderate: 500 999 cells/microliter Severe: less than 500 cells/microliter This is an example of which type of variable?
4. What type of variable is Cancer recurrent/not recurrent 5 years after initial treatment.
1. Nominal
2. Continuous
3. Ordinal
4. Categorical- dichotomous
Fraction of a group possessing a clinical condition or outcome at a given point in time.
What is prevalence?
Occurs when exposure is associated with another variable and the effect of one is confused with or distorted by the effect of the other
What is confounding?
Difference between Efficacy vs Effectiveness
Efficacy-answers the questions about treatment under ideal circumstances. Very specific. Phase 2
Effectiveness- answers the questions about treatment under ordinary circumstances. Real-world questions. Phase 3
Question 1 of 3: You are on a rotation in Spokane, Washington, which has a population of 200,000. It is estimated that of these people, 800 have cardiovascular disease (a treatable, but incurable disease). There are 90 new cases and 10 deaths each year from myocardial infarctions caused by the disease. There are 100 deaths per year from all causes. The best estimation of the prevalence of cardiovascular disease in your population of interest on the first day of your investigation is given by:
A: 10 / 200,000
B: 90 / 200,000
C: 800 / 200,000
D: 80 / 200,000
Question 2 of 3: You want to learn more about the health status of people in Spokane before they develop cardiovascular disease. You want to evaluate whether high blood cortisol levels lead to early development of cardiovascular disease. The best way to learn more about this process is to design a:
A: Prospective cohort study during which you measure cortisol levels over time and record the incidence of cardiovascular disease
B: Prospective cohort study during which you measure cortisol levels over time and record the prevalence of cardiovascular disease
C: Case-control study during which you measure cortisol levels over time and record the incidence of cardiovascular disease
D: Case-control study during which you measure cortisol levels over time and record the prevalence of cardiovascular disease
Question 3 of 3: When you track how many cases of cardiovascular disease (CVD) arise in your study subjects, you need to calculate the following values:
A: Prevalence = (number of new CVD cases) / (time * number of people at-risk for developing CVD)
B: Prevalence = (number of people with high cortisol levels) / (time * number of people at-risk for developing CVD)
C: Incidence = (number of new CVD cases) / (time * number of people at-risk for developing CVD)
D: Incidence = (number of people with high cortisol levels) / (time * number of people at-risk for developing CVD)
1. C: 800 / 200,000
2.A: Prospective cohort study during which you measure cortisol levels over time and record the incidence of cardiovascular disease
3.C: Incidence = (number of new CVD cases) / (time * number of people at-risk for developing CVD)
List Bradford hill criteria
Strength of association
The stronger the association, the more likely it is that the relation is causal.
Temporal relationship
Exposure always precedes the outcome.
Consistency
The association is consistent when results are replicated with different people under different circumstances and with different measurement instruments.
Theoretical plausibility
It is easier to accept an association as causal when there is a rational and theoretical basis for such a conclusion.
Coherence
The association should be compatible with existing theory, hypotheses, and knowledge.
Specificity
In the ideal situation, the effect has only one cause.
Dose response relationship
An increasing amount of exposure increases the risk.
Experimental evidence
Any related research that is based on experiments will make a causal inference more plausible.
Analogy
Sometimes a commonly accepted phenomenon in one area can be applied to another area.
What is person years
1. The study you conduct has the ability to be valid within the environment it was created. Degree to which results of a study are correct for the sample of patients being studied.
2. You conduct a study evaluating the efficacy of bright light therapy to treat depression in Portland. You put up signs with a phone number to call for interested participants around town, and receive 80% of your phone calls from medical students who would like to participate and otherwise meet eligibility criteria. This is a threat to which of the following in your study?
1. What is internal Validity?
2. What is External Validity?
What is Researcher Allocation, Participants, practitioners, and Data Analyst?
Step one: None
Step Two: Researcher Allocation
Step Three: Participants, Practitioners
Step Four: Data Analyst
a. Occurs when the methods of measurement are dissimilar among groups of patients
b. Occurs when comparisons are made between groups of patients that differ in determinates of outcome other than the one under study
c.Remember an exposure
a. What is measurement bias?
b. What is selective bias?
c. What is recall bias?
Draw three graphs and identify mean, median and mode on the graph
1. Skewed left
2. Skewed Right
3. Non skewed
Mode is the highest point in the graph, mean is towards the tail, median is in between
Question 1 of 5: The next 5 questions are from your rural health rotation, where you are working at a small pediatric clinic in Utah. Over time, you have noticed that you have had several young patients with leukemia. You aren t sure if this is atypical or not, but you do know that there was uranium mining as recently as five to ten years ago in the area, and wonder if this could be related to the leukemia rates. Which type of study could best help you answer this question?
A: Case-Control
B: Cross-sectional
C: Retrospective cohort
D: Prospective cohort
Question 2 of 5: You ve decided on the appropriate study type above. Which of the following is the correct pairing of study type and measure of association?
A: Case-control study and Relative Risk
B: Case-control study and Odds Ratio
C: Cohort study and Relative Risk
D: Cohort study and Odds Ratio
E: Both B and C
F: Both A and D
Question 3 of 5: Which of the following is the best control group for this study?
A: Children from your clinic who were exposed to uranium mining and have leukemia
B: Children from your clinic who were NOT exposed to uranium mining and have leukemia
C: Children from other clinics in the area with leukemia
D: Children who had leukemia but then recovered
E: Children from your clinic without leukemia
Question 4 of 5: You find that there are 15 children with leukemia and match them to 15 control patients. You find that 8 of the children with leukemia live close to the uranium mining site, whereas only 2 of the control patients do. Calculate the correct measure of association (odds ratio or relative risk) for this study design.
A: (8/7) / (2/13)
B: (8/15) / (2/15)
C: (8/10) / (7/20)
D: (8/13) / (7/2)
Question 5 of 5: Which of the following is the correct interpretation of this measure of association?
A: For patients with leukemia, the odds of living near a uranium mine are 8 times greater than patients without leukemia.
B: For patients with leukemia, the relative risk of living near a uranium mine is 2.3 times greater than patients without leukemia.
C: The relative risk of developing leukemia given that you live near a uranium mine is 2.3 times greater than if you do not live near a uranium mine.
D: The odds of developing leukemia given that you live near a uranium mine is 8 times greater than if you do not live near a uranium mine.
1.A: Case-Control
2.E: Both B and C
3.E: Children from your clinic without leukemia
4.A: (8/7) / (2/13)
5. A: For patients with leukemia, the odds of living near a uranium mine are 8 times greater than patients without leukemia.
1. Which of the following best describes a dynamic population ?
A: It is uniquely suited for cohort studies.
B: It is rapidly increasing in size.
C: It is the best kind of population for a random sample.
D: People are continually entering and leaving the population.
2.At your lab meeting you are discussing expansion of your project to other sites. What do you need to consider first to ensure your study sample represents the population of interest? Choose the best answer.
A: Consider how the population from which you drew the sample for this study is similar and different from the populations at those sites.
B: Use identical recruitment methods to assemble your study sample.
C: Adjust your recruitment methods as needed to obtain a representative sample of your population of interest.
D: A and C
1. D: People are continually entering and leaving the population.
2.D: A and C
1. (C/C+D)-(A/A+B)
2. 1/(C/C+D)-(A/A+B)
3. 1- ((A/A+B)/(C/C+D))
1. Absolute Risk Reduction
2. Number Needed to Treat
3. Relative Risk Reduction
1. Prior to conducting this study, the supplement curcumin was tested in mouse models of implantable contraception and found to improve vaginal bleeding. The study was then replicated in non-human primates and found to have similar results. If curcumin is found to also decrease vaginal bleeding in women with implanted contraception, which of the following criteria will most likely be strengthened?
A: Analogy
B: Consistency
C: Strength of association
D: Dose-response relationship
2. The study protocol describes that half of study participants will receive curcumin, while half will receive a placebo. After the study is completed, participants in both groups report a decrease in vaginal bleeding, though the curcumin group has less severe vaginal bleeding than the placebo group. Even though the placebo group also has a decrease in vaginal bleeding, which of the following criteria is strengthened by these results?
A: Temporality
B: Consistency
C: Biologic plausibility
D: Strength of association
3. A cross-sectional study of groundwater fluoride ingestion and childhood cognitive functioning implicates fluoride as a potential neurotoxin. Investigators posit that properties of fluoride ions behave like lead ions in certain types of brain matter. Which Bradford Hill criteria would this argument satisfy?
A: Analogy
B: Consistency
C: Dose-response relationship
D: Reversibility
1. B: Consistency
2.D: Strength of association
3. A: Analogy