12 - Key approaches Flashcards
The Canadian Health Measure Survey aims to collect important health information through __________________________________
interview, blood and urine
The CHMS is led by (3):
- Statistics Canada
- Health Canada
- Public Heath Agency of Canada
US NHANES is led by:
the National Center for Health Statistics
Researcher intervenes to change exposure then observes/measures what happens (cause-effect): _____________________
Experimental studies
Researcher observes/measures exposure and outcome (does not manipulate) , environment is not changed, not a true experiment, associations not causations:_______________________
Observational studies
Groups are being compared, aims to associate exposure/intervention and outcome: _________________
Analytical studies
Help identify patterns and generate hypothesis, case report, surveys, fact-finding inquiries, frequency and distribution of single variables:
Descriptive study
Explain case reports:
- They are an in-depth analysis of a single individual, unit or event
- Direct observation and questioning
- Provides considerable detail
- Usually concern rare events
What are 3 challenges associated with case reports?
- Difficult to draw clear causal linkages
- Generalizability of findings
- Potential for observer bias
What are the 3 types of analytical studies?
1) Cohort (prospective)
2) Case-control
3) Cross-sectional
- Characterize (observe) exposures in participants and then track them overtime
- Compared exposed vs controls =
Cohort (prospective)
- Enroll participants with disease or outcome and find matched controls
- Compare previous exposures between groups =
Case-control
- Enroll participants and measure exposures and health simultaneously
- Snapshot =
Cross-sectional
What study is an example of a cohort study?
Nurses Health Study
What are the pros of a cohort study (3):
- can match subjects at baseline
- establish timing of events
- can standardize exposures
What are the cons of a cohort study (4):
- associative study (not causal)
- blinding is difficult
- not randomized
- rare diseases need large sample size and long follow-up
What study is the opposite of a cohort study:
CASE-CONTROL STUDY
Start with an outcome/disease and then work backwards to identify possible causes:
case-control study
What are the pros of a case-control study (3):
- Relatively quick and cheap
- Most feasible for rare disorders or outcomes with long latency period
- Fewer subjects needed than other studies
What are the cons of a case-control study (5):
- Associative study (not causal)
- Reliance on recall and records to determine exposures (past diet??)
- Not randomized
- Control groups hard to find
- Selection bias
Study at one point in time to determine if there’s an association between exposure and health:
Cross-sectional study
What are the pros of a cross-sectional study :
Relatively cheap and simple
What are the cons of a cross-sectional study :
- Associative study (not causal)
- Recall bias problems
- Confounders may be unequally distributed
What tool can you use to make sure you’re doing an observational study the right way?
The STROBE Checklist
What does STROBE stands for:
Strengthening the reporting of Observational studies in Epidemiology
T or F: incomplete and inadequate reporting of research hampers the assessment of the strengths and weaknesses of the studies reported in the medical literature. Readers need to know what was done (and what was not), what was done, what was found, and what the results mean. Recommendations on the reporting of studies that are endorsed by leading medical journals can improve the quality of reporting
T
What are the 2 sub-studies under experimental studies:
1) Randomized controlled trial (where there’s random allocation)
2) Non-randomized controlled trial
Ex: Vaccines for COVID-19, blind the population and blind the researcher so no one knows what is tested where (1/2 are getting the vaccine and the other 1/2 are not getting anything). This is an example of a ________________-
Randomized clinical trial (RCT)
What checklist do we use to check what information to include when reporting a randomized trial:
The CONSORT
What does CONSORT stand for:
Consolidated Standards of Reporting Trials
T or F: Consort is a 25-point checklist, is evidence-based, there’s a minimum set of recommendations for reporting randomized trial
T
Explain the Consort flow chart:
1) Enrollment (assessed for eligibility)
2) Allocation (received the allocated intervention)
3) Follow-up (discontinued intervention/give reasons)
4) Analysis (excluded from analysis/give reasons)
Collects all studies on a topic and statistically combines results:
Systematic review and meta-analyses
What are the 3 type of studies that yield the strongest evidence on the evidence pyramid:
1) Meta-analysis
2) Systematic review
3) Randomized control trial
Bradford Hill Criteria for ___________:
Causation
- strength (effect size)
- consistency (is it reproducible?)
- specificity (specific population, specific site)
- temporality (cause and then effect
- biological gradient (greater exposure = greater incidence
- plausibility - a believable mechanism linking
- coherence - epid and lab studies
- experiment
