Evidence-Based Medicine Flashcards
Evidence-Based Medicine
The conscientious, explicit, and judicious use of current best evidence in making decisions
about the care of individual patients
Why do we need evidence based medicine
- Ensures medicines are of high quality
- recommendation made for patient and other health proffessionals in phsrmacy services
Secondary studies
- Clinical practice guidelines
- Meta analysis systematic review
Experimental study design
1 level of evidence
- Randomised control trials prospective test treatment
Level 3 source of evidence
Case control study
- Subjects have outcomes of interest looking for risk factors
observtional study
Cross-sectional study
- Doesn’t concider time doesn’t tell causation
- Obsrvations occour concurently
- Participants are selected based on set inclusion and exclusion criteria
- Population based research
Experimental studies
Animal lab studies
- Animal research uses animals to test potential pharmaceuticals prior to human trials
Disadvantages of animal study
- Application is limited considering the difference between human
and animal physiology - Experiments are undertaken in a highly controlled environment
Groups in cross sectional study
- Exposed and outcome present
- Exposed and no outcome
- Uexposed and outcome present
- Unexposed and no outcome
Advantages of cross sectional case control study
- Less expensive
- Easier to do and take less time
- Useful when obtaining follow-up data that is difficult to obtain due to
the nature of population being studied - More efficient if the disease is rare
- This design may be the only ethical way to evaluate something
Disadvantage of case-control study
- Potential recall bias
- Subject to selection bias
- Generally do not allow investigators to calculate an incidence (new cases can’t use retrospective data) or absolute risk
Cohort study
- Outcome is not know
- Identify 2 cohort one recives intervention other not exposed
- Follow and observe to see effect
- Almost always prospective, but sometimes can be
retrospective
Advantages of cohort study
- Can more clearly show the time of exposure and development of the outcome
- Allows for evaluation of more than one outcome as it relates to an exposure
- Allows for calculation of incidence (in new cases)
Disadvantage of cohort studies
- Can be expensive and time needing follow up
- loss of follow up introduces bias
- May not be good for rare disease
Randomised controlled trial
- Randomly assign subject to either have control (placebo) or new medication
- Is a prospective study
Advantages of random control trial
- Considered the gold standard
- This design allows for washout of most population bias
- Reduced influence by confounders
- Reduced variability in the outcome(s)
- Easier to blind patients than observational studies
Disadvantages of randomised contol trial
- Time consuming trial
- Tend to be more expensive
Sytamatic review
- Locates, appraise and synthesize the best available evidence relating to a specific research question and evidence-based answers.
- How to deliver interventions or to make changes to policy
Meta-analysis
- Summarize the results of
independent studies by combining information from all relevant studies - More precise estimates of the effects of health care than those derived from the individual studies included within a review
Advantages of Meta-analysis
- Objective evalulation of reseach findings
Disadvantage of meta-analysis
- Not all topics have sufficient research evidence to allow a meta-analysis to be conducted
Advantages of NICE guidelines
- Thorough and transparent development process to ensure fairness.
- Representative stakeholders involved in the process.
- Directly applicable to patients.
- Often take into account a huge number of potential treatments and drug classes, e.g. type 2 diabetes guidelines.
- Complex issues simplified.
- Regularly reviewed.
- Take into account cost considerations
Disadvantages of NICE guidelines
- May involve conflict of interest however resolved by conflict of interest
- Large amount of resources required
Primary endpoint
- The main result/s that is measured at the end of a
study to see if a given intervention was effective - ,ust be clinically relevant
Secondary endpoint
- These are additional events of interest, but which
the study may not be specifically powered to assess
Patient-oriented endpoints
- An ideal endpoint should be a valid and applicable measure of how a patient feels, functions or survives
- Measure directly the number of patients with conditions
- e.g. - Neither vitamin prevents cancer or cardiovascular disease
Advantages of Patient-oriented endpoints
Measures of true patient benefit, clinically meaningful,
clinical certainty
Disadvantages of Patient-oriented endpoints
Need large sample size, longer trial duration, more
expensive, delay in potentially beneficial medicines coming to market
Disease oriented endpoints
Do not directly measure how a person feels, functions or survives, but which should be so closely associated with a clinically meaningful endpoint
- e.g. - Beta-carotene and vitamin E are good antioxidants
Advantages of Disease oriented endpoints
smaller sample size, shorter trial duration, less
expensive, expediates medicines to market
Disadvantage of Disease oriented endpoints
May not relate to clinically meaningful outcomes,
may not change at all stages of disease, may predict that harmful treatments are effective
Absolute risk reduction
- Difference between two rates trial 1 and trial 2
See the difference in percentage/100
Relative risk reduction
- Difference in event rate expressed
relative to what you started with - Divide trial 1 by 2
(First percentage - second percentage/first)
NNT (Number needed to treat)
Number of patients
we need to treat for one patient to
benefit.
1/ARR
