-
Factors determining study design
- ability to answer primary research question
- potential new treatment
- probability of risk to participants
- probability of participants likely to benefit
- size & accessibility of studied population
- how data is used
-
investigators will take the primary research question and develop
- a hypothesis to test
- very important when trying to evaluate the study
-
observational studies are good for
discovering things that need to be investigated further
-
interventional studies are good for
investigating the effect of a particular change
-
Prospective study characteristics
- forward in time
- gather data on events as they happen
- creating chart
- interventional trials
-
retrospective trial characteristics
- backward in time
- gather data from historical documentation
- looking at chart
- subject to recall bias
-
observational trials may be
pro or retrospective
-
uncontrolled trial characteristics
- results of one group's experince
- can't determine cause and effect
- interventional or observational
- no "control group"
-
Controlled trial characteristics
- One group's results compared to results of group not experiencing event
- two or more groups
- interventional or observational
-
when determining efficacy, the control is
placebo
-
when determining efectiveness/efficaciousness the control is
active
-
Dose comparison trial controls are
two different doses along with placebo group
-
Randomized trial characteristics
- must have 2 or more groups
- individuals randomly assigned
- may be possible in retrospective studies
-
Non-randomized trial characterizations
- may be 1 or more groups
- individuals assigned to group based on certain traits or by choice of investigator
- groups may not be similar
-
when factors are known that are highly likely to affect the results or be predictive of disease progression
- stratification
- ie: try to put the same number of smokers in each group
-
Parallel trial characteristics
- two or more groups have different experiences at the same time
- most common
-
cross-over trial characteristics
- one group having two or more experiences at different times
- each individual serves as his own control
- "paired data"
- smaller groups required
-
advantages of Study diagrams
- visual aid
- understand complex study designs
- identify potential problems
-
Single Blinded trial characteristics
either pt or investigator knows assignment
-
double blinded trial characteristics
- neither patient nor investigator knows assignments
- more objective observation of results
-
Un-Blinded trial characteristics
- investigator and pt know what group pt is in
- outcomes may be reported differently
-
Inclusion criteria
- "to be in the study, pt must..."
- aids in addressing hypothesis
- "fine-tune" a diagnosis
-
Exclusion criteria
- "to be in the study, a pt must not..."
- reduces risk and complications for pt
-
single study site
- smaller numbers of pt
- easy communication
- easy data collection
-
multiple study sites
- large number of pt
- challenging to coordinate research efforts
-
Type I clinical study
- prospective
- interventional
- controlled
- statistical power
-
Type II clinical study
- prospective
- interventional
- controlled
- no power
-
Type III clinical study
- prospective
- observational
- comparison groups
- cohort studies
-
Type IV clinical study
- retrospective
- observational
- comparison groups
- case control study
-
Type V clinical studies
- prospective
- interventional or observational
- uncontrolled
-
Descriptive study designs
- document and communicate experience
- share observations & unusual events
- case report or series
-
Explanatory study design
- examin cause
- efficacy/etiology using method of comparisons
- clinical trials, case controls, cohorts, cross-sectional
-
Examples of interventional/experimental studies (clinical trials)
- superiority
- non-inferiority
- equivalency
-
Observational studies seek
- causes
- etiologies
- predictors
-
examples of observational studies
- cohort
- case control
- cross-sectional
-
Cohort study
- prospective or retrospective
- observational
-
Case Control Study
- retrospective
- observational
- match a person with an outcome of interest to a similar person without and look for differences in variables
-
cross sectional study
- slice in time
- observational
- blend of cohort and case study
- prevalence study
|
|