Just because using a treatment is associated with people getting better or worse, that doesn’t mean that the treatment made them better or worse.
Sometimes researchers find a link or connection (an association) between something people do – like going to the doctor – and something that happens to them – like being sick. This does not mean that what they did caused what happened to them. For example, it is more likely that people went to the doctor because they were sick than that going to the doctor caused them to be sick.
When there is a link between people using a treatment and how sick or healthy people are, the treatment may or may not have made them more or less sick. The link may have happened by chance or it may be because of something else.
For example, in some countries ice cream sales and drowning are linked. When more ice-cream is sold, more people drown. That does not mean that eating ice cream causes people to drown. A more likely explanation is that people eat more ice cream when it is hot and they swim more when it is hot. So telling people to stop eating ice cream (a treatment) is very unlikely to reduce the number of people who drown!
BEWARE of claims that a treatment has an effect because using the treatment is associated with people getting better or worse.
REMEMBER: Ask if you can be sure that there aren’t other reasons for the association.