Screening test: What the result tells you

What screening is and what it is not

The basic idea of screening has a long history and is well described in medicine. The classic principles of Wilson and Jungner, published by the World Health Organization in 1968, state that screening is an initial step in an apparently healthy group. Its purpose is to identify people for whom closer examination may be useful. Determining whether a condition is actually present happens afterward.

For self-tests, this means a questionnaire can collect signs and show you whether your answers fall within a positive range. But it cannot determine what is causing them. Symptoms such as concentration problems, fatigue, or low mood can have many possible causes. That is why screening is a starting point, not an endpoint.

A simplified calculation example

The following numbers are made up and are used only for illustration. They are not study results. Suppose a screening test uses a cutoff to divide a group into positive and negative results. Of 1,000 people, 150 fall within the positive range. This does not mean that 150 people have the condition. It means only that 150 people may benefit from further evaluation. How many actually have the condition depends on the test quality and on how common the condition is in that group.

If you lower the cutoff, more people fall within the positive range. You identify more affected people, but you also incorrectly flag more unaffected people as positive. If you raise it, the opposite happens. A cutoff is therefore always a tradeoff, not a sharp dividing line between healthy and ill.

The cutoff

The cutoff is the score at or above which a result is considered positive. It comes from studies in which an instrument was tested in a specific group. This matters because a cutoff is tied to those exact conditions, including the specific instrument, the language version, the population studied, the setting, and sometimes sex. A value that works well in a clinical population may not have the same meaning in the general population. We therefore use cutoffs only when the instrument and its source support them, and we explain them on the relevant test page.

Common confusion

The most common mistake is treating a positive screening result as a diagnosis. A positive result does not mean that a condition is probably present, at least not without considering how well the test performs and how common the condition is. A negative result is also often treated as an all-clear. It is not. A low score can make a condition less likely, but it does not reliably rule it out, especially when someone compensates well for their difficulties or has trouble recognizing them in self-report.

What this means for self-tests on medtests.net

Many self-tests on medtests.net are screenings in exactly this sense. The Depression Test uses the PHQ-9, the Anxiety Test uses the GAD-7, the ADHD Test uses the ASRS, and the Autism Test uses the AQ-10. The same logic applies to all of them. A positive score is a reason to have the issue assessed by a doctor or psychotherapist, not proof. In the Eating Disorder Test with the SCOFF, for example, a low score explicitly does not provide an all-clear because certain patterns are detected less well. You can find the detailed scoring information for each instrument on its test page.

What the term does not mean

Screening is not a diagnostic judgment and it is not a test that can rule out a condition. It does not tell you that you definitely have a condition, and it does not tell you that you are definitely healthy. Statements such as "above the cutoff, you have the condition" or "below the cutoff, everything is fine" are incorrect. A self-test provides orientation and does not replace medical, psychotherapeutic, or diagnostic evaluation. If symptoms are affecting you, talking with a qualified professional can be useful regardless of the result.