- a type of retrospective observational study
- control patients are ‘matched’ using some criteria (age, gender), typically should have no history of the disease of interest and should be representative of the general population
- begins with a definition of outcome or interest
- aims to identify potential risk factors associated with outcomes
- measures exposure to risk factors
- outcome = in case and controls
- odds ratio used to quantify risk, and can be adjusted for confounders (e.g. using logistic regression)
- quick, cheap and easy
- cases and controls may be sampled from pre-existing databases
- useful for identifying possible risk factors of a condition
- useful for studying rare conditions and those with a long latency period following exposure to risk
- not prone to loss to follow-up, unlike cohort studies
- may be used as the initial study generating hypotheses to be studied further by larger, more expensive prospective studies
- controls are often recruited by convenience sampling, and are thus not representative of the general population and prone to selection bias
- subject to confounding (other risk factors may be present that were not measured)
- not always possible in case-control studies to predict whether exposure to the risk factors preceded development of the disease or condition
- relative risk can not be determined as the incidence or prevalence of the condition of interest cannot be estimated in the population
- not suitable if exposure to the risk factors of interest is rare, as few of the cases and controls will have been exposed to them
- cannot determine causation, only association
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
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