Are you kidding me? That is so unsurprising. Chronic pain in any part of the body makes people more depressed and anxious.
In the article they mention rating scales that I am not familiar with: The Dysfunctional Attitude Scale (DAS) and the Hospital Anxiety and Depression scale (HAD). Years of pain may help to strengthen your dysfunctional attitude. Too bad it doesn't help you to get anywhere.
It makes me think of the pain scales often seen in hospitals and on surveys.
This plain vanilla pain scale seems to cover most people's pain.
This one that I saw from @carvicab has a lot more of the flavour of pain
Having a dysfunctional attitude and catastrophic pain scale ratings is not a good way to get better treatment. In seeking treatment for pain it seems that some doctors withhold it on principal, and others offer it so that you will go away. Pain pills are so often not the answer but it's a complex area.
For an innovative point of view about a scale for patient-identified outcomes see Nick Dawson's blog. It has a very constructive viewpoint.