The Mankoski Pain Scale is the most commonly used one:
Here is a link to it...

http://www.wemsi.org/painscale.html

I think pain is a very subjective thing. Some people can withstand alot of pain, and others cannot.

One can learn to dissociate some pain, through autohypnosis and relaxation techniques. Some research is being done with this type of therapy so that dependence on drugs can be less.

There is a neuronal pathway in the brain that processes pain. And evidence is mounting that it becomes a LEARNED process like other things we learn. So if one allows pain to become your master, it may never go away centrally. The example given is the phantom pain amputees feel, which continues in the brain after the limb is gone. So it is very important NOT to dwell on discomforts, to shift attention and focus elsewhere, so the pain loop does not become permanent.

This is one reason I prefer patches and local pain interventions because stopping the signal at the source seems to prevent future chronic issues. The Lidoderm patches work this way, as well as topical RX creams compounded or OTC like Biofreeze.