Study deisgn and levels of evidence Flashcards
What are the 5 aims of epidemiology?
- Identify the cause of disease
- Measure the extent of disease
- Study the progression and prognosis of disease
- Evaluate methods of treating and preventing disease
- Inform policy development
What level of evidence are case series, post test or pre test and post test, cross sectional?
Level 4
Define a case series study and its aim
Describes the characteristics of a group of people who has the same disease or exposure.
Theaim is yo understand the demographic, presentation, prognosis of those with the disease.
Define a cross sectional study and what is this good to use for
Takes a selective population and measures health information at a point in time like a snapshot of health.
Involves asking participants with a questionnaire. health surveys is an example
Good way to assess exposure and outcomes and health needs of a population
Define case control study and what is it commonly used for. List some pros and cons
Starts with cases with the diseases and uses a comparison group without the disease called controls.
Asked about previous exposures to different risk factors.
Commonly used in outbreak investigation.
Pros
- quick and cheap
- good for uncommon disease
Cons
- not rare exposures
- difficulty in control selection
- recalling exposures lead to inaccuracy
What is a cohort study ? List some pros and cons
A group of people followed over a period of time and risk factors are collected. Outcomes compared to those exposed and not exposed to risk factor.
Pros
- time sequence can be determined
- collection of outcome
Cons
- high cost - can be large number of people
- not good for rare diseases
Define a clinical trial
an intervention is done on a group of people and the outcome is studied.
Types of intervention - meds, vaccine, advice
Outcome- change in disease, behavioural change
