This means that people who believe themselves to be well have tests to find out if they are at risk of particular conditions. If someone has a symptom, screening tests are not applicable - they are only for people with no symptoms.
To try and stop something from happening again, for example, if someone has had a stroke, secondary prevention aims to stop another stroke from happening.
Another term for placebo, but often used to describe ‘sham surgery’ when patients either have a ‘real’ operation or a procedure that feels and looks like a real operation but isn’t.
When people feel something is wrong, for example, a fever, a cough, and muscle aches can be symptoms of the flu, or a breast lump might be a symptom of cancer. Symptoms are felt by the person having them.
A way of searching through all the research on a subject, looking carefully for research that hasn’t been published in medical journals or isn’t obvious. This is usually a good way of making sure that all the research is weighed up before judging whether treatments work or not.