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SPHG 712 Exam 2 With Complete
Solution
What is an etiology study? - ANSWER Does X cause Y? Casual Inference - ANSWER -Inductive/deductive reasoning -Koch's postulates -Bradford Hill guidelines -Causal pies -Counterfactuals -Causal diagrams (DAGs (directed acyclic graphs) What are the 3 questions to ask about exposure and outcome? - ANSWER - Exposure before outcome? -Outcome before exposure? -Exposure and outcome at same time? What are the two questions to ask about study designs? - ANSWER - When were exposure and outcome measured? -What was the unit of analysis? What are the two outcomes for unit of analysis? - ANSWER Group level Individual level Case control study - ANSWER Cases leads to the exposure
Controls and looking at exposure Compare the two Do case control studies happen in the past, present or future - ANSWER Past Retrospective cohort - ANSWER Exposure (+) then compare disease risk and rates Exposure (-) then compare disease risk and rates Do retrospective cohort studies happen in the past, present or future - ANSWER Past Prospective cohort study - ANSWER Exposure (+) then compare disease risk and rates Exposure (-) then compare disease risk and rates Do prospective cohort studies happen in the past, present, or future - ANSWER Future after start of study RCT, intervention studies - ANSWER Intervention (+) compare disease risk and rates Intervention (-) compare disease risk and rates Do RCT and intervention studies occur in the past, present, or future - ANSWER Future after start of study Cross sectional study - ANSWER Exposure (+/-) and Outcomes (+/-) measured at one point in time Cross sectional studies compare what - ANSWER risk rates
Can the participants have the behavior change at the start of a cohort study?
- ANSWER No What are the two types of cohort studies? - ANSWER 1. retrospective study: formed in the past OR start now but form cohort in the past
- prospective study: starts now; goes into the future
Example of retrospective study that starts now but was formed in the past - ANSWER Looking at workers exposed to radiation from the Tennessee Valley or in various radium mining
Pro's of cohort studies - ANSWER -directly estimates rates and risks -good for rare exposures -good for multiple outcomes -provide evidence of temporality between exposure and outcome
Cohort study measures of disease occurrence - ANSWER Risk (R) Rate (IR)
Cohort study measures of association - ANSWER Risk difference (RD) Risk ratio (RR) Rate ratio (IRR)
RCT vs Cohort studies - ANSWER Both follow participants over time RCT investigator assigns the exposure (i.e. getting drug vs. placebo)
Experimental vs. Nonexperimental studies - ANSWER Experimental: -investigator randomly assigns exposure -EX: randomized control trials
Nonexperimental: -Observations (doesn't assign exposure) EX: case control, cohort, ecologic, cross sectional
When are RCT's used - ANSWER -test new drugs or medical treatments -drug or treatment is randomized -intervention group and control group should be comparable in all aspects -strongest evidence for causal inference -helps prevent bias
Types of blinding - ANSWER non-blinded single blinded
What is a 'classic' ecologic study - ANSWER Characteristics of a 'classic' ecologic study are both exposure and outcome are measured at the group level
Time frame for ecologic studies - ANSWER - One point in time (cross sectional)
- Multiple points in time (time trend)
Do ecologic studies use prevalence? - ANSWER Yes - one point in time
Do ecologic studies use rates and risk? - ANSWER Yes -multiple points in time
Ecologic studies associations with ratios - ANSWER -prevalence -prevalence odds -risk -rates
Ecologic studies associations with differences - ANSWER -prevalence -risk -rates
Def of ecologic fallacy - ANSWER Concluding that an association between exposure and disease at group level is therefore true at individual level
Case series/case reports include what - ANSWER only include cases, no control group
What kind of report is common in medical literature - ANSWER Case series/case reports
Can you make conclusions about exposure outcome relationships with case series/case reports? - ANSWER No
What kind of study is hypothesis generating - ANSWER Case series/case reports
What do you compare in cross sectional diseases - ANSWER risk rates exposures
What do cross sectional ecologic studies entail - ANSWER investigator
What does control group refer to in cohort study - ANSWER they are in the unexposed group
What does control group mean in case control studies - ANSWER a group of individuals selected without the disease who if they had developed the disease would be selected as a case
key steps for case control study - ANSWER 1. define and select cases
- define and select controls
- compare exposure prevalence
What is a case selection population based - ANSWER specific geographic region chosen as source population with certain restriction criteria (age, SES, race)
In January 2016, you, an investigator, want to evaluate MMR vaccination and a potential association with autism diagnosis in Vietnam. You used a administrative claims database associated with the state run health care plan system to define your study population. You defined your study population as all women who were enrolled and pregnant in 2009. You followed them and their children through their child's birth and early childhood until 2014. This study design is likely
Case control Ecologic cross sectional retrospective cohort case series prospective cohort pre/post intervention comparison - ANSWER Retrospective cohort
Investigators will likely choose to prioritize calculating which measure of association/comparison for the new NIH study mentioned in a previous question?
prevalence ratio odds ratio risk ratio rate ratio - ANSWER Rate ratio
If instead, the study had investigated the relationship of MMR and autism at one point in time, rather than following individuals over time, which measures of association could you have calculated?
prevalence odds ratio
case control ecologic cross sectional retrospective cohort case series prospective cohort pre/post intervention - ANSWER ecologic cross sectional
You calculate a risk ratio of 1.35, with a 95%Confidence Interval of (0.72, 5.5). How would you interpret this confidence interval?
statistically significant not statistically significant - ANSWER not statistically significant
You calculate a risk ratio of 1.35, with a 95%Confidence Interval of (1.05, 5.5). How would you interpret this confidence interval?
statistically significant not statistically significant - ANSWER statistically significant
The study design for the retracted Wakefield article is the following
case control ecologic cross sectional retrospective cohort case series prospective cohort pre/post intervention - ANSWER case series
Up until a few years ago, Guiyu China, was one of the largest sites for electronic waste processing in the world. You suspect that heavy metal exposures is associated with increasing the risk of autism. You and your research team recruit 100 children diagnosed with autism by age 4 in the city's largest clinical practice. You select controls from children who are visiting the practice for their annual wellness check up at the time the case is diagnosed with autism. You then use blood lead levels as a proxy measure for heavy metal exposure. What is the study design?
case control ecologic cross sectional retrospective cohort case series
OBJECTIVE: To report ASD occurrence by MMR vaccine status in a large sample of US children who have older siblings with and without ASD. DESIGN, SETTING, AND PARTICIPANTS: A study using an administrative claims database. Participants included children continuously enrolled in the health plan from birth to at least 5 years of age during 2001-2012 who also had an older sibling continuously enrolled for at least 6 months between 1997 and 2012. EXPOSURES: MMR vaccine receipt (0, 1, 2 doses) between birth and 5 years of age. MAIN OUTCOMES AND MEASURES: ASD status defined as 2 claims with a diagnosis code in any position for autist - ANSWER retrospective cohort
BACKGROUND: Public trust in immunization is an increasingly important global health issue. Losses in confidence in vaccines and immunization programmes can lead to vaccine reluctance and refusal, risking disease outbreaks and challenging immunization goals in high- and low-income settings. National and international immunization stakeholders have called for better monitoring of vaccine confidence to identify emerging concerns before they evolve into vaccine confidence crises. METHODS: We perform a large-scale, data-driven study on worldwide attitudes to immunizations. This survey - which we believe represents the largest survey on confidence in immunization to date - examines perceptions of vaccine
importance, safety, effectiveness, and religious compatibility among 65, individuals across 67 countries. Hierarchical models are employed to probe relationships between individual- and country-level socio-economic fact - ANSWER cross sectional
Background: The aim of this study was to determine whether racial/ethnic differences in psychosocial measures, independent of economic status, exist among a large population of pregnant nulliparas. Methods: Between October 2010 and September 2013, nulliparous women at eight U.S. medical centers were followed longitudinally during pregnancy and completed validated instruments to quantify several psychosocial domains: Cohen Perceived Stress Scale, trait subscale of the Spielberger Anxiety Inventory, Connor-Davidson Resilience Scale, Multidimensional Scale of Perceived Social Support, Krieger Racism Scale, Edinburgh Postnatal Depression Scale, and the Pregnancy Experience Scale. Scores were stratified and compared by self-reported race, ethnicity, and income. Results: Complete data were available for 8,128 of the 10,038 women enrolled in the study. For all measures, race and ethnicity were significantly associated (p < - ANSWER cross sectional
BACKGROUND: Alcohol control policy has a fundamental role in limiting negative health, economic and social harm caused by alcohol consumption. However, there is substantial international heterogeneity in country-level policy adoption, implementation and monitoring. Comparative measures so far focused on
cohort
