Class 15 Flashcards
(33 cards)
Research evidence pyramid:
Increasing strength of evidence
In vitro ('bench') research---->Animal research----> Case Reports----> Case Series----> Ecological----> Cross-Sectional----> Case-Control----> Cohort----> Pragmatic and Interventional Studies----> Systematic Reviews
----> Meta-AnalysesWhat is the most useful and appropriate study design?
IT DEPENDS!!!!
On the question being asked and the desired perspective
Quantitative study
Numbers used to represent data
Interventional Vs. Observational
Qualitative study
Words used to represent data
-Open ended questions, look for consistent words, phrases, concepts, themes, between participants
Interventional study
Forced allocation to study groups
Authors/researchers intervene, pick the study and groups
Observational study
No forced allocation to study groups
Let exposures occur naturally
Study design selection based on:
1) Perspective of research question (Hypothesis)
2) Ability/Desire of researcher to force group allocation (randomization)
3) Ethics of methodology
4) Efficiency and Practicality (time/resource commitment)
5) Costs
6) Validity of acquired information (Internal Validity)
7) Applicability of acquired information to non-study patients (External Validity; Generalizability)
Stating a research question
“I wonder if….” statement
Helps frame study intent and can direct researcher to more effective study design to answer question
Null hypothesis
Researchers either accept or reject this perspective, based on results (data analysis)
A research prospective which states there will be NO (true) difference between the groups being compared
Making the assumption that we aren’t going to find anything; have to have results that will change my mind of the null hypothesis
Most conservative and commonly utilized
Various statistical-perspectives can be taken by the researcher:
1) Superiority:
- Think one treatment/exposure will be better
2) Noninferiority:
- Just show that at least the new drug isn't worse
3) Equivalency:
- Both drugs are equivalent
Alternative hypothesis
A research perspective which states there will be a (true) difference between the groups being compared
Errors in Inaccurately-Accepting or Rejecting Null Hypothesis
Type I Error: False positive
-Telling a man he is pregnant
Type II Error: False negative
-Telling a woman who is 9 mo. pregnant that she isn’t pregnant
Interventional study designs considered “experimental”
Investigator-selects interventions (exposure)
- **There IS researcher-forced group allocation
- Randomization processes commonly used to accomplish this
Observational study designs considered “natural”
Researchers “observe” subject-elements occurring naturally or selected by individual (naturally or freely)
Useful for unethical study designs using forced interventions
Most observational study designs not able to prove causation
***There is NO researcher-forced group allocation
Interventional study design
Increasing evidence: Preclinical phase (Phase 0) Phase 1 Phase 2 Phase 3 Phase 4
Observational study design
Increasing evidence: Case reports/series Cross-sectional Ecological Case-control Cohort
Human studies: Population
Population:
- 1st step is to pick a population to study and take a sample of that population that is representative of the big group
- All individuals making up a common group; from which a sample (smaller set) can be obtained, if desired**Not to be confused with the ‘study population’, which is simply the final group of individuals selected for a study
Human studies: Sample
A subset or portion of the full, complete population (‘representatives’)
Useful when studying the complete population is not feasible
Random processes commonly utilized to draw sample
Human studies: study population selection based on:
1) Research hypothesis/question
2) Population of interest
3) Group of individuals most useful and applicable to answer the research question
4) Inclusion and Exclusion selection criteria (Interventional studies) and Case and Control group OR Exposed and Non-Exposed group selection criteria (Observational studies)
- Desired vs. Logical vs. Plausible selection criteria
- These absolutely impact generalizability!!!
- External validity
5) Ethics
- Principles of bioethics MUST be met…
- Some don’t agree w/ use of placebo if treatment is avail.
- Recall Null Hypothesis perspectives:
- Superiority
- Noninferiority
- Equivalency
6) Equipoise
- genuine confidence that an intervention may be worthwhile (risk v. Benefit) in order to use it in humans
Equipose***
Define on exam
Genuine confidence that an intervention may be worthwhile (risk vs. benefit) in order to use it in humans
4 key principles of bioethics
Autonomy
Beneficence
Justice
Nonmaleficence
4 key principles of bioethics: Autonomy
Self-rule/self-determination.
Participants must:
- Decide for oneself, without outside influences
- No coercion, reprisal, financial manipulation
- Have full & complete understanding of risks vs. benefits
- No misinfo, incomplete info, or ineffectively-conveyed info
4 key principles of bioethics: Beneficence
To benefit, or do good for, the patient (not society)
Past unethical research has violated this when thinking about society over the individual
In this case, individual»»> society
4 key principles of bioethics: Justice
Equal & fair treatment regardless of patient characteristics
4 key principles of bioethics: Nonmaleficence
Do no harm. Researchers must not…
- Withhold information
- Provide false information
- Exhibit professional incompetence
