If you take a sampling of patients from a GP practice, it's obviously going to skew results by not factoring in those who have simply given up trying to get a GP to do their job. This is bad inference. Especially as it's typically advised that unless there are specific reasons for it, healthy young people do not need to take regular appointments with a GP. In my country I think it's only around 50 that GPs are advised to make regular check-ups. When I got sick, I had not seen my GP in something like 6 years. This is pretty typical and it's expected that sick people would naturally have more contact with health care than healthy people advised not to do that unless necessary.
And this is the explanation. Patients who would be categorized in this "with severe fatigue" get the message that they are not welcome and give up. Which happens to literally be the point of doing that, the entire premise for this approach is to exclude those patients from medical practice because they are too expensive and annoying and we get the damn message that we are not welcome.
Other than being officially advised, you mean? That seems pretty clear. It's literally advised. I'm not sure what could possibly be hard to understand here. When you insult people over something they stop bringing it up. The insults are explicitly on purpose based on a belief system meant to discourage exactly this. The response is obviously not to bring it up, in part because it immediately becomes the obsessive focus from a psychological waste of efforts.
Since it's research on primary care, perhaps the first three are GP's not normally involved in research.
