MEASURING PAIN
The following is an editorial on the topic of Measuring Pain. It is provided complements of Jim Meadows from his regular newsletter on orthopedic physical therapy. It is from Newsletter #4 which can be found with the rest of his newsletters in the Newsletters section of Swodeam.com .
The reason for this editorial is that I have noticed lately that PTs on my courses have varying and often incorrect ideas on why they are using numeric or visual analogue pain scales and I would like to give my perspective on the issue. Over the past few years there has been a move towards using a numeric scale for rating pain. There is little doubt that this move has been accelerated, if not initiated, by the US insurance companies who are for the large part demanding its use on their forms. But leaving the troubled waters of insurance companies aside, the question needs to be asked whether or not using a visual analogue scale or a numeric scale for pain grading is clinically such a good idea. The use of these types of scales goes back to research so that reports of pain intensity could be standardized on an ordinal scale so used to staticize (is that a word?) changes in pain intensity with interventions of interest. The scales were not intended for clinical use although they are utilized here more than anywhere else. To me the most ridiculous aspect of pain scales is their use period. For a profession that is trying to become more scientific you have to wonder at the use of a measure that has been validated against a gold standard that itself was previously in widespread use, was cheap and required little training to use. The gold standard of the validity studies for the pain scales was the patients report of pain intensity. Somebody out there please explain the logic and science of this.
Some of the reasons for using a numeric pain scale (and this discussion will concentrate on the numeric scale as this is the pre-eminent scale in clinical practice) is that compared to a verbal description of pain intensity it is that it is more objective, that it provides absolute levels of the patients pain, that it more easily demonstrates changes, that the patient understands it better, that the therapist understands it better, that it is more scientific, that the insurance companies require it. With the exceptions of the last two arguments none of the above are at all true.
It is certainly not more objective just because you write down a number in place of a word, in fact it is arguable that it is less objective. First the scale has to be understood by the therapist, then it must be explained to the patient who then has to convert his/her pain experience into an unfamiliar scale, then the therapist has to convert the patients conversion into his/her conception of the scale. Without detailed training in the scale by both the therapist and the patient there is no compelling reason to believe that these conversions result in an accurate understanding of the patients pain level by the therapist. Further, pain is not an objective experience but a subjective one and no amount of fiddling with scales will make it objective, so the attempt to do so is just plain silly. Lets look at objectivity in the explanation of the scale, because even if the scale was objective, a subjective explanation of the scale would negate such objectivity even if it existed. It is the upper end of the scale that is problematic. The 10 is variously described as emergency room pain, the worse pain you can imagine, labor pain, suicide pain, and so on. For me the worse pain imaginable is having a large rusty, red hot, blunt knife inserted into a particularly sensitive body part and twisted compared to this pretty much all musculoskeletal pain would pale into insignificance. What now is a 3 on this scale. None of these descriptors are any more objective than saying the patient a 10 is excruciating pain that is intolerable and requires immediate and profound medication. As you can see the so-called objective scale is made subjective by describing the 10 in terms of subjective experience. Even given, for the sake of argument, that the 10 is objective how objective is the 8. Is this excruciating, severe or moderately severe. No this scale is not more objective than words and is likely to be less precise.
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