Observational studies Study type: Case series
Design: Describes several individual patients with the same diagnosis, treatment, or outcome.
Measures/Example: Description of clinical findings and symptoms. Has no comparison group, thus cannot show risk factor association with disease.
Observational studies
Study type: Cross-sectional study
Frequency of disease and frequency of risk-related factors are assessed in the present.
Measures/Example: Asks, “What is happening?” Disease prevalence. Can show risk factor association with disease, but does not establish causality.
Observational studies
Study type: Case-control study
Design: Retrospectively compares a group of people with disease to a group without disease.
Measures/Example: Asks, “What happened?” Odds ratio (OR). Control the case in the OR. Patients with COPD had higher odds of a smoking history than those without COPD.
Observational studies
Study type: Cohort study
Design: Compares a group with a given exposure or risk factor to a group without such exposure.
Measures/Example: Looks to see if exposure or risk factor is associated with later development of disease. Can be prospective or retrospective. Disease incidence. Relative risk (RR). People who smoke had a higher risk of developing COPD than people who do not. Cohort = relative risk.
Observational studies
Back of card:
Study type: Twin concordance study
Design: Compares the frequency with which both monozygotic twins vs both dizygotic twins develop the same disease.
Measures/Example: Measures heritability and influence of environmental factors (“nature vs nurture”).
Observational studies
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Study type: Adoption study
Design: Compares siblings raised by biological vs adoptive parents.
Measures/Example: Measures heritability and influence of environmental factors.
Observational studies
Study type: Ecological study
Design: Compares frequency of disease and frequency of risk-related factors across populations.
Measures/Example: Measures population data not necessarily applicable to individuals (ecological fallacy). Used to monitor population health. COPD prevalence was higher in more polluted cities.
Design: Describes several individual patients with the same diagnosis, treatment, or outcome.
Observational studies Study type: Case series
Frequency of disease and frequency of risk-related factors are assessed in the present.
Measures/Example: Asks, “What is happening?”
Observational studies
Study type: Cross-sectional study
Design: Retrospectively compares a group of people with disease to a group without disease.
Observational studies
Study type: Case-control study
Design: Compares a group with a given exposure or risk factor to a group without such exposure.
Observational studies
Study type: Cohort study
Compares the frequency with which both monozygotic twins vs both dizygotic twins develop the same disease.
Observational studies
Back of card:
Study type: Twin concordance study
Design: Compares siblings raised by biological vs adoptive parents.
Observational studies
Back of card:
Study type: Adoption study
Design: Compares frequency of disease and frequency of risk-related factors across populations.
Observational studies
Study type: Ecological study
Phase 1 clinics
Phase 2 clinical trials
Phase 3 clinical trial
Phase 4 clinical trial
phase 5 clinical trial
Crossover study
Definition: Compares the effect of a series of ≥2 treatments on a participant. Order in which participants receive treatments is randomized. Washout period occurs between treatments.
Allows participants to serve as their own controls.
Front of card:
Bradford Hill criteria
Back of card:
Definition: A group of principles that provide limited support for establishing evidence of a causal relationship between presumed cause and effect.
Definition: A group of principles that provide limited support for establishing evidence of a causal relationship between presumed cause and effect.
Bradford Hill criteria
Bradford Hill criteria
Strength:
Bradford Hill criteria Consistency:
Repeated observations of the findings in multiple distinct samples.