Week 1 Flashcards
Evidence based medicine EBM
The conscientious, judicious and explicit use of current best evidence when making decisions about the care of individual patients
Clinical experience
Clinical research
eliciting patient preferences
The evaluation bypass
Procedures are evaluated to either be useful or not useful
Only useful ones are taken up into the health service
An example of harm caused by lack of evidence
Thalidomide
The AAAA framework
Finding and critically appraising evidence
Assess- what type of healthcare question- what type of study
Access- finding the ‘best’ evidence (validity and reasoning)
Appraise - evaluating the quality of the evidence. Interpreting the results
Act- is this evidence relevant to my clinical practice should this evidence change my practice
Importance of the AAAA framework
An essential professional and academic skill
Medical knowledge is continually evolving
The medical profession frequently fails to use effective treatments
Keeping up to date is a lifelong commitment for every doctor
You need to develop and use the skills to find, appraise and act on research evidence
Categories of healthcare questions
Frequency - ecological; cross-sectional study
Aetiology - case-control; cohort
Prognosis
Effectiveness and side effects - RCT
Diagnosis - special cross-sectional/ test accuracy study
Patient experience - qualitative research
Epidemiological studies
Descriptive or analytical
Descriptive studies
By definition observational
Used to answer questions about frequency and patterns of disease
-how much disease
- distribution of disease: time, place, persons
Used for hypothesis generation. Often precede more resource intensive analytic studies
Descriptive studies: case report/ case series
Case report: a detailed report of an unusual ‘condition’ or ‘occurrence’ in a single patient
Case series: a detailed report of an unusual ‘condition’ or ‘occurrence’ in several patients
Descriptive studies: cross sectional study
A study in which information is collected in a planned way from individuals in a defined population at one point in time
Also known as a prevalence study; an incidence study; a survey
Descriptive studies: ecological studies
A study in which information is collected from a whole populations to compare disease frequencies
In one population at different points in time (population defined temporally)
Between different population (population defined geographically) at the same time period
Analytical studies
Key feature: explicit comparison of 2 or more groups of individuals
Aim is to establish whether an exposure causes an outcome
Exposure may be harmful or beneficial
Types:
Observational- researcher is an observer of exposures and outcomes
Interventional/ experimental- researcher allocates exposure and observe outcomes
Analytic- observational studies
Exposure is not under the control of the researcher because of ethical or logistic constraints for example if investigating whether an exposure causes harm/ causes disease
A ‘natural experiment’
Types:
Case control: study starts with identification of the outcome (e.g disease)
Cohort: study starts with identification of the exposure ( eg risks factor)
Analytic observational studies: case control study
Compared those with a condition (cases) to those without the condition (controls). Subjects are grouped for the comparison according to the outcome of study
The level of “exposure” to one or more factors is measured and compared between the 2 groups (cases and controls)
If the level of exposure is higher in the cases than in the controls the exposure might be a risk factor
Analytic observational studies: cohort studies
A cohort study compares those exposed to a factor of interest to those not exposed to a factor of interest subjects are grouped for comparison according to whether they have been exposed to or not
The 2 groups are followed up over time and the amount of disease developing over a specified time period is compared between the 2 groups
If the incidence of the outcome is higher in the exposed compared to the unexposed the exposure might be a risk factor