Week 1

Question 1

Evidence based medicine EBM

Answer 1

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

Question 2

The evaluation bypass

Answer 2

Procedures are evaluated to either be useful or not useful
Only useful ones are taken up into the health service

Question 3

An example of harm caused by lack of evidence

Answer 3

Thalidomide

Question 4

The AAAA framework

Answer 4

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

Question 5

Importance of the AAAA framework

Answer 5

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

Question 6

Categories of healthcare questions

Answer 6

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

Question 7

Epidemiological studies

Answer 7

Descriptive or analytical

Question 8

Descriptive studies

Answer 8

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

Question 9

Descriptive studies: case report/ case series

Answer 9

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

Question 10

Descriptive studies: cross sectional study

Answer 10

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

Question 11

Descriptive studies: ecological studies

Answer 11

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

Question 12

Analytical studies

Answer 12

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

Question 13

Analytic- observational studies

Answer 13

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)

Question 14

Analytic observational studies: case control study

Answer 14

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

Question 15

Analytic observational studies: cohort studies

Answer 15

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

Question 16

Case control or cohort study

Answer 16

How many exposures do you want to capture
How many outcomes do you want to measure
How long between exposure and development of outcome
Is the outcome rare or common
Case control: can investigate multiple exposures, can only investigate one outcome, recruitment is based on presence or absence of outcome so do not have to wait for this to occur, groups for comparison are based on the presence of the outcome: active case finding overcomes the problem of rare outcomes
Cohort study: can only investigate one exposure, can investigate multiple outcomes, you have to wait for the outcome to occur after recruiting on the basis of exposure so loss to follow up is a problem for diseases with long latency period, for rare outcomes a lot of exposed individuals would need to be recruited to be sure of enough outcomes occurring

Question 17

Analytic experimental studies clinical studies: the randomised controlled trial RCT

Answer 17

A controlled clinical trial is an experimental study where researchers decide whether participants receive the new intervention being tested or receive a control treatment usually either the standard/ existing treatment or placebo
Controlled clinical trials are used to investigate effectiveness
Participants consent to researchers deciding which treatment they receive
Randomised controlled clinical trials RCTs have design features that increase their internal validity (reduce bias )

Question 18

Effectiveness is the balance between harms and benefits

Answer 18

Pre-requisite for an RCT (experiment) is that there is genuine uncertainty about which treatment is best: equipoise and that the new treatment will do more good than harm

Question 19

Evidence for cause and effect: hierarchy of evidence

Answer 19

Randomised controlled trails
Cohort studies
Case control studies
Case series and reports
Expert opinion evidence

Question 20

Qualitative research

Answer 20

Healthcare questions about patient/ carer/ health professional experiences
Collection of non numerical data about peoples subjective understanding of their lives and experiences
In depth study of a small number of individuals in a specific setting rather than aiming for generalisability across different settings in quantitative research which requires larger sample size
Interpretation of the meaning of the data helps us understand individuals behaviour and social phenomena
Multiple methods available for collecting data including direct observation of behaviour, individual interviews and group interviews (focus groups)

Question 21

Study for questions about patterns of disease

Answer 21

Descriptive studies: cross sectional studies and ecological studies

Question 22

Study for questions about cause and effect

Answer 22

Analytic studies
Observational: cohort and case control designs
Experimental