STUDY DESIGNS FOR HEALTH ARE QUESTIONNAIRES Flashcards
What is evidence based medicine
The conscientious, judicious and explicit use of current best evidence when making decisions about the care of individual patients
What 3 sectors make up EBM
- Clinical research
- eliciting patient preferences
-Clinical experience
Give two examples of harm caused by lack of evidence
- Sudden infant death syndrome (SIDS)
- Thalidomide
What are the two types of epidemiological studies
- Descriptive
- Analytical
Why is the AAAA framework important? (3)
- Medical knowledge is continuously evolving
- Medical profession frequently fails to use effective treatment
- Keeping up to date is a lifelong commitment for a doctors
What are epidemiological studies and what are they used for?
- Studies that are descriptive/ observational
- Used to answer questions about frequency and pattern of diseases e.g how much disease and distribution of disease
- Used for hypothesis generation
What are the two types of descriptive studies?
- Case report
- Case series
- Cross sectional studies
- Ecological studies
- Analytical studies
What is the AAAA framework
It is a way of finding and critically appraising evidence. The 4 As stand for
- Assess - what type of healthcare question - what type of study
- Access - Finding the best evidence (validity and relevance)
- Appraise - evaluating the quality of evidence and interpreting the results
- Act - is the evidence relevant to my clinical practice and should this evidence change my practice
What are case reports
A detailed report of an unusual ‘condition’ or ‘occurence’ in a single patient
What are case series
A detailed report of an unusual ‘ condition’ or ‘occurrence’ in a series of patients
What are cross sectional studies, what are they also known as?
- A study where information is collected in a planned way from individuals in a defined population at one point in time
- Also known as prevalence study, incidence study, survey
What is an example of a cross sectional study
- Office for national statistics
- People, populations and community surveys
- Health and social care
What is the definition of an ecological study?
- A study in which information is collected from a whole population to compare disease frequencies
How can an ecological study be carried out
- In one population at different points in time
- Between different populations at the same period of time
What is an analytical study and what is the aim of it?
It is an explicit comparison of two or more groups of individuals. Its aim is to establish whether an exposure causes an outcome (cause and effect)
What are the two types of analytical studies
- Observational (cohort and case control)
- Interventional/ experimental (intervention and clinical trials)
What are analytical observational studies
They are natural experiments - the researcher isn’t in control of a persons exposure to something that causes harm or disease. They are not in control because of ethical or logistical constraints
Describe the two types of analytical observational studies
- Case control - this is where a study starts with the identification of the outcome (disease). Those with the condition are compared to those without (control group)
- Cohort - study starts with the identification of the exposure e.g risk factor. Those with the risk factor are grouped and compared against those who don’t have the risk factor. If the incidence of outcome is higher in those with the risk factor compared to those without then there might be a risk factor
Examples of cohort studies (4)
- Nurses health studies
- Whitehall studies
- Framingham heart studies
- National child development study (UK)
Give 3 pro’s of case control studies
- Can investigate multiple exposures
- Don’t have to wait for outcome to occur
- Groups for comparison are based on the presence of the outcome and this overcomes the problem of rare outcomes
What is a con of case control studies?
Can only investigate one outcome
Give one pro of cohort studies
Can investigate multiple outcomes because exposure to one thing can result in lots of different outcomes
Give 3 cons of cohort studies
- Can only investigate one exposure
- Have to wait for outcome after exposure - this can result in problems with follow up
- For rare outcomes, a lot of exposed individuals would need to be recruited
What is a controlled clinical trial and what are they used for?
An experimental study where researchers decide whether participants will receive the new intervention being tested or receive a control treatment e.g placebo. They are used to investigate effectiveness
Advantage of randomised controlled clinical trials (RCTs)?
Increases internal validity
What is the pre-requisite for an RCT
- There is genuine uncertainty about which treatment is best
- Equipoise - balance of interests
- The new treatment will do more harm than good
Give the order of the hierarchy of evidence
- RCT
- Cohort studies
- Case control studies
- Case series and reports
- Expert opinion and anecdotal evidence
What is qualitative research?
- Collection of non numerical data about peoples subjective understandings of their lives and experiences
- in depth study of small amount of individuals, doesn’t aim for generalisability
- Interviews, direct observations
