Understanding Evidence-Based Pain Management (EBPM)An important deficiency of many research reports is that they focus on pain relief of a therapy as a statistical phenomenon, rather than examining whether there were clinically meaningful benefits for patient care. A recent study investigated characteristics of “responders” to fibromyalgia therapy that can make a difference in achieving successful outcomes that are durable over time.
Clinical trials of drugs and other treatments for pain often demonstrate “statistically significant” pain reductions in patients without demonstrating any “clinically meaningful” reductions, wrote Gabriel Miller in the September edition of Pain Medicine News [Miller 2010]. The article was based on a presentation at the 2010 meeting of the American Pain Society (APS) in which researchers noted how, with an adequately large sample size, a one-point reduction on a visual analog scale (VAS) can be statistically significant, yet may do nothing to truly improve a patient’s pain or quality of life.
The researchers further reported that patients who seem to achieve less than certain pain threshold at 6 months post-treatment — specifically, a score of 4 on a 10-point VAS scale — generally continue to improve, whereas those who never get down to that threshold more often return to pretreatment pain levels. Their study involved 301 female patients with fibromyalgia who underwent a standardized course of rehabilitation (not further described). Overall, there was a statistically significant reduction in pain intensity from baseline in almost all patients (p<0.001), achieving an average score of 5 on the 10-point scale. However, at the 6-month followup only 73 patients reported pain levels below a score of 4, which was considered the threshold between “mild” and “moderate to severe” pain; whereas, the majority of patients reverted back to having debilitating pain.
The researchers observed that one way of resolving the conflict between statistically significant versus clinically relevant reductions in pain relies on responder analysis; that is, looking separately at patients who were either “responders” or “non-responders” to the intervention under investigation. In their study, the 73 patients who were responders had pain below a 4 on the VAS and continued to improve; eventually, this group’s pain score dropped more than 3 points from baseline, to a 2.2 on average.
Another group, of 140 patients, who also were hovering around a score of 5 on the VAS immediately after treatment turned out to be non-responders and went in the exact opposite direction; at 6 months this group’s average pain was higher than their baseline score. Hilary Wilson, PhD, from the University of Washington who participated as a researcher in the study, noted, “It really demonstrates that something happens when you can get a patient’s pain at a 4 or less. They are able to somehow improve their function, get back into their life, and continue to realize improvements. If you can get your patient in treatment below that threshold, they can continue to get better.”
COMMENT: Perspectives from this article shed more light on the typical flaws in research in the pain management field and what practitioners and their patients should expect from effective therapies. Research reports focusing on average, or mean, improvements in pain (as many do) are unhelpful. Readers do not know whether all patients improved to some degree or a only small segment of patients benefitted greatly, which skewed the overall average higher. Researchers need to present their data in ways that can help identify which patients, if any, can benefit most from a particular therapy.
One approach, as noted in the above article, is to identify the characteristics of “responders” who achieve a “minimal clinically important difference” (MCID), such as a predetermined improvement from baseline in self-reported VAS scores. We have previously described [here] that a 10% to 20% reduction in VAS score is generally considered as minimally acceptable, with 30% to 36% reductions being moderate, and a 50% or greater reduction deemed substantial.
One of the problems with data such as self-reported VAS scores is that there can be what is called a “regression toward the mean” over time. That is, regardless of whether the treatment was effective, patients may drift back toward their initial scores; hence, group averages may eventually reflect no meaningful differences in treatment effects. The research reported at APS suggests that a VAS score of 4 is somewhat of a critical threshold for identifying patients who have meaningfully benefitted from a therapy and will continue to show improvements, as compared with other patients who may have benefitted initially but may revert back to their initial pain status or worse. Of course, the interpretation of “clinically meaningful” is somewhat relative and depends on how high a level of pain the patient was experiencing before treatment; however, it is something to consider.
REFERENCE: Miller G. Studying the Difference Between ‘Statistical’ and ‘Clinically Meaningful.’ Pain Medicine News. 2010(Sep);8(9) [article available here].
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6 comments:
I really question the clinical (as opposed to statistical) usefulness of these sorts of grading scales. I've always been a bit bewildered when asked to rank my pain from 1 to 10, and this is despite the fact that I've learned to be quite sensitive to tiny gradations in the level and quality of pain in order to manage it. The problem is that these feelings are impossible to communicate precisely, regardless of how precisely I am able to distinguish them in myself.
My experience is that a score of 4 or less allows the person to sleep better, function better over all and also make decisions that are clear and useful. Anything above that threshold and the person is so preoccupied with pain relief that nothing else matters and if they can not sleep or function they will continue down the rabbit hole of pain. and The related depression and hopelessness continues to spiral as well.
These treatments can help sufferers of chronic pain such as fibromyalgia, cancers, among others but it is also advisable to take medicines such as hydrocodone and lortab especially in non-chronic pain
This was an interesting article, but I can't help but view it as Highly Questionable at best. One man's VAS of 4 may very well be another man's 6, or another's 2. Pain awareness, pain sensation, pain tolerance, the whole concept, is such a "personal phenomenon" that setting a specific level, such as "4", to be determined as the "break point" seems as arbitrary and 'non-specific' as the initial question itself. Personally, as someone who has dealt with pain - real, physical pain, caused by physical abnormalities - since the age of eight or nine as I can best recall, how can I compare what I would consider a '4' to another's percieved '4' without feeling like I'm just pulling a number out of the ether? Personally, I didn't even realize what true pain was until I was well into my twenties, simply because my main point(s) of reference up to that point, my past personal pain experiences, were always dismissed as "a pulled muscle" or "just growing pains" or "just a part of being a kid." I wish I had a nickle for every time I was told to "just walk it off."
In the end, all I really know is that 1) my pain is real, at least as far as I'm concerned; 2) it has a definite effect on every other facet of my life; 3) I just want it to Go AWAY; 4)Finally, it's up to me to take charge of my pain control/treatment/etc. because no one else is going to do it for me, or even really give a darn, as long as MY Pain doesn't interfere with them living Their life. And that's just the way it is. Oh, and one more thing: 50 years from now, who's gonna care if my VAS was 4 or 40?
Thank You.
EE
The comments above make a good point. One person’s ‘4’ may be another person’s ‘6’ and so on. Yet, since pain is so subjective the VAS score was developed as one way of getting a grasp on its intensity. What may be most important for the individual patient is that pain treatment helps to lower their personal VAS scores over time.
The VAS has been a useful research tool. Researchers look at average VAS scores across groups of patients with similar (albeit not absolutely identical) pain conditions. If there are enough subjects in each group, improvements in VAS scores can be a helpful measure of treatment success (as compared with the group who did not receive the treatment); although, there will always be some patients who do better than others, even in the group receiving a placebo or no treatment.
The authors of the above research article remind us that statistically significant differences are all well and good, but we need to keep in mind what are “meaningful” improvements to patients. They’re on the right track, I believe. --- SBL
A scale where the 10 is "need to be in the hospital and 0 is no pain." A happy face and gradations of happy to sad with tears. How can that translate into "electricity" like when you fall asleep on your arm and it begins with pins and needles but hurts a heck of a lot more. Sudden electric-like pain that causes you to jerk your leg up and yell in pain. Back pain so bad you consider suicide. Constant body pain until you feel like your life will never be without this torture. Until people are given the courtesy of being believed when they say they are in pain, treated for the pain appropriately and quickly, the scales will be meaningless. What is the difference between 4 and 6? To one in pain it is just a number. You do not even remember what level you said 5 min later. Sure it helps in the documentation and insurance payments. It might even help you think there is improvement. Regarding function, what is the number? What does it mean? I never understood the difference and rarely was asked to describe the pain in my terms.
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