Mental Health Mismeasurement.
In common with an unfortunately many papers on physically debilitating conditions, this paper uses standard mental health tools (PHQ9,...) with the normal recommended cuts for a healthy patient.
At the same time as measuring significant physical disability to the point many patients have had to give up work, or reduce work, the scales useduncritically ask patients 'Do you enjoy the things you used to do' and 'Are you worried about your health'.
These answers supposedly inform on mental health.
All of the MH tools used need careful thought to see what the appropriate baseline that would be expected given the persons physical condition.
Using the standard cuts makes as much sense as concluding that people with one leg are at high risk of low blood pressure following asking them 'do you wobble when you standup'.
This is more than an academic issue. This mismeasurement gets swallowed into meta analysis, where it is even further distanced from verification, and then may be used to drive treatment policy based on the fact that anxiety/depression is a meaningful component of the illness.
Competing interests: No competing interests