Causation
-statistical inference that suggests the exposure produces the effect based on: theory, scientific models, biology
association
-a statistical inference that suggests the effect is more likely with a particular exposure
c
Which form of association occurs by chance or bias?
a) causal association
b) confounded association
c) false association
b
Which form of association is caused by the correlation of a third variable?
a) causal association
b) confounded association
c) false association
a
Which form of association confirms the criteria of causality?
a) causal association
b) confounded association
c) false association
Confounding bias
-occurs when the relationship between exposure or treatment and outcome is affected by another variable or a group of variables.
must be associated with the outcome & exposure; not affected by exposure
What is true of confounders?
selection bias
-occurs when procedures are followed in selecting study participants such that participants who get selected in the study are either more likely or less likely to experience the outcome than those not in the study sample.
self-selection bias
-when participants themselves decide to participate in or drop out of a study
referral bias
-if a patient is referred to another provider or referred to laboratory tests because of an exposure to a drug
information bias
-errors in measurement regarding information on the study participants
misclassification bias
-type of measurement error due to misclassifying exposed as unexposed
recall bias
-occurs when participants in a research study or clinical trial do not accurately remember a past event or experience or leave out details when reporting about them
detection bias
-cases are given more importance than controls in collection of information, or when the exposed participants are followed more closely than the unexposed
b
Which methodology of controlling for bias involves assigning individuals to a treatment or control group based on a mechanism that gives the same probability of being in either of the two groups?
a) blinding
b) randomization
c) restriction
c
Which methodology of controlling for bias involves selecting subjects who have the same value for a variable that might be a confounder?
a) blinding
b) randomization
c) restriction
a
Which methodology of controlling for bias involves ensuring that the patient or data collector is ignorant of the treatment assignment?
a) blinding
b) randomization
c) restriction
a
Which methodology is aimed to correct information bias at the study design-level?
a) blinding
b) randomization
c) restriction
matching
-Involves identifying some characteristic that is alleged to be a source of bias (i.e., a confounder) and matching cases with controls or exposed subjects with unexposed subjects with respect to that characteristic
stratification
-Analysis of the exposure-outcome association is performed within each of several subgroups created based on the (proposed) confounding variable
-Can combine effect estimates for all strata into one weighted summary effect measure (called a pooled or common effect
multivariable modeling
What do we use to control for multiple confounders at the same time?
propensity score methods
-designed to assign participants to an assigned treatment group based on observable characteristics; patients with similar probabilities are considered similar patients.
construct a measure; obtain outcomes
what are the two main important steps in risk adjustment?
risk adjustment/ case-mix
-The process by which the health status of a population is taken into account when making meaningful comparisons of patterns or outcomes of care or setting capitation rates
construct a measure
Which step of risk adjustment involves creating or setting a measure to define risk or severity?
obtain outcomes
Which step of risk adjustment involves the researchers using the adjusted risk severity?
rcts; cohort
________ exclude patients with comorbidities while _________ include patients to examine real-world outcomes.
diagnosis-based measures
-–based on diagnoses codes ICD10CM (e.g., Charlson comorbidity index, Elixhauser index, APACHE)
pharmacy-based measures
-based on medication use (e.g., chronic disease score (CDS), RxRisk score)
to balance the treatment groups based on calculated observable characteristics to mimic a randomized controlled trial
What is the purpose of propensity scores?
similar patients
Patients with similar probabilities are considered what?
match patients on scores before analysis, as a predictor variable, to do a stratified analysis, and as sampling weights in outcome analysis
How can we use propensity scores?
sensitivity analysis
-Systematically repeating the analysis by varying assumptions eachtime, in order to assess how sensitive the results obtained are to thevariations in model assumptions and whether the results areconsistent across the variations in assumptions
Risk adjustment
-the process by which the health status of a population is taken intoaccount when making meaningful comparisons of patterns oroutcomes of care or setting capitation rates
case-mix adjustment
What's another term for risk adjustment?
comorbidities
______ are unrelated to causality to the principal diagnosis, but may be important risk factors?