Evidence Based Medicine (3&4) Flashcards
Hierarchy of evidence
- Meta-analysis of RCTs (randomized clinical trials)
- Single large RCT
- Cohort Study
- Case-control study
- Case series
- Expert opinion
- Meta-analysis of randomized clinical trials (RCTs)
Considered the best evidence and the least biased.
Pool of single large RCTs
- Single large RCT
This is the second best evidence, only after a large pool of these
- Cohort Study
(level 2)
Observational study and more biased than RCTs
- Case-control study
(level 3)
Observational study and more biased than RCTs
- Case series
(level 4)
Observational study and without a comparison group
- Expert opinion
The worst type of evidence
What are the common pitfalls in the conduct of clinical research
- Lack of randomization
- Lack of concealment of randomization
- Lack of blinding
- Wrong intention to treat analysis
- Errors in hypothesis tesgting
- Lack of randomization
(common pitfalls in the conduct of clinical research)
Randomization is important because:
- it gives every patient an equal probability of being enrolled to either group.
- It is the single most important technique to limit bias in clinical research. Thus, studies that fail to randomize patients introduce an important bias in the measurement of the outcome measure.
Why is randomization so important? (1)
it gives every patient an equal probability of being enrolled to either group.
Why is randomization so important? (2)
It is the single most important technique to limit bias in clinical research. Thus, studies that fail to randomize patients introduce an important bias in the measurement of the outcome measure.
Concealed randomization ensures that surgeons are unable to ________ the treatment to which their next patient will be allocated.
(common pitfalls in the conduct of clinical research)
predict
The safest manner in which to limit the occurrence of failed concealment is a _________
remote 24-hour telephone randomization service
If randomization is concealed, then the physician cannot ______ the patient will be allocated to at the time of patient consent and application of exclusion/inclusion criteria.
predict to which treatment
Randomization techniques that preserve ________ can include telephone and internet-based randomization.
concealment
_____ also guards against potential bias in a research study.
Blinding
While blinding is feasible in most, if not all, drug trials, it is rarely feasible in a ______trial
Surgical
When ______ is not possible, investigators should take care to ensure _________ assessment of the outcome measures if they require some interpretation (i.e. Radiographic healing of bone, assessment of clinical outcomes, physical examination
blinding is not possible; independent
When blinding is not possible then researchers should ensure that
Independent assessment of the outcome measures if they require some interpretation (i.e. Radiographic healing of bone, assessment of clinical outcomes, physical examination
- Lack of concealment of randomization
Basically being able to predict what treatment the patient will be allocated to
- Lack of blinding
Basically knowing and having bias in a surgical study (ex. giving the more sick some treatment to show more improvement)
- Wrong intention to treat analysis
When some patients undergo the alternative treatment they were not allocated to either by mistake or the result of technical difficulties
Even when proper randomization is performed, some patients undergo the alternative treatment they were not allocated to either by mistake or the result of technical difficulties with one treatment
This approach seems to be COUNTERINTUITIVE at first glance, it PRESERVES the value of randomization: on average known and unknown prognostic factors will be equally distributed across both treatment groups and therefore the treatment effect will be primarily determined by the assigned treatment.
- Errors in hypothesis testing
A common pitfall in clinical trials
Evidence based medicine is defined as
the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.
Bias
Any tendency which prevents unprejudiced consideration of a question.
When does bias occur?
When systematic error is introduced into sampling or testing by selecting or encouraging one outcome or answer over others.
What does bias cause?
E estimates of association to be either larger or smaller than the true association.
In extreme cases, can cause a perceived association which is directly opposite of the true association. (Example: HRT and Heart Disease)
- Preclinical Research
types of research
The evaluation of potential therapeutic interventions in cells and animals.
All drugs require data from various toxicological preclinical studies to support their potential safety in humans before clinical studies can begin
Types of research:
- Preclinical Research
2. Clinical Research
- Clinical Research
The study of human disease, including its prevention, diagnosis and treatment, using human participants, human populations or materials of human origin (mainly involve human participants)
Clinical trial
A research study involving HUMAN participants that is designed to answer specific questions about the safety and efficacy of a biomedical INTERVENTION (e.g., drug or device).
Clinical trials studies are
intended to discover or verify the clinical, pharmacological or pharmacodynamic effects of a drug, or study the absorption, distribution, metabolism and excretion of a drug.
The first “clinical trial”?
: Nebuchadnezzar in the book of Daniel whom ordered to eat meat and wine
The first REAL clinical trial?
James Lind and Scurvy Trial
James Lind
Is considered the first physician to have conducted a controlled clinical trial of the modern era.
While working as a surgeon on the ship Salisbury, Dr. Lind was appalled by the high mortality from scurvy among the sailors.
Drug and device development
- Starts with extensive preclinical laboratory (one of the research types) research involving experiments in animals and human cells.
- If the preclinical research is ________, the manufacturer requests approval from Health Canada to ______ research in humans.
[Drug and device development]
successful; continue research in humans