Getting personal on overdiagnosis: On defining overdiagnosis from the perspective of the individual person.

How can overdiagnosis be defined, explained, and estimated on an individual level? The answers to this question are essential for persons to be able to make informed choices and give valid consents for tests. Traditional conceptions of overdiagnosis tend to depend on counterfactual thinking and prophetic abilities as you would have to know what would happen in the future if you did not test now. To avoid this, overdiagnosis can be defined in terms of the chance of diagnosing a person with a disease when this does not avoid or reduce manifest disease. To be able to relate this to 1's own life and deliberation, I argue that we need answers to specific questions such as the following: If I am tested, and the test and subsequent test results are positive, but I am not treated, what is the chance that I would not experience and suffer from manifest disease? A definition of overdiagnosis that aims at providing answers to this question is as follows: Prospectively overdiagnosis (of an individual person) is given by the estimated chance that a person having a positive test result would not experience and suffer from manifest disease if not treated or followed up in any way. Getting personal on overdiagnosis directs the attention of overdiagnosis estimates towards what matters in medicine: the experience of individual persons.