Survey says... Pain Intensity or Pain Frequency?

One of the things we like to do in the top secret PIRL lab is wile away our time coming up with new an innovative ways to quantify the unquantifiable.  This is one of the reasons we love the field of pain measurement - not only is it clinically relevant and the number 1 reason that people come to see physiotherapists, but it is also an intensely personal and subjective experience.  Here at the PIRL we subscribe to the 'pain is what the patient says it is, and occurs when the patient says it does' doctrine, regardless of what is happening in their other physiological systems (although we poke around in those as well).  

About 5 years ago, as part of a project we launched exploring the concept of recovery from musculoskeletal injuries, we held a series of focus sessions, one-on-one interviews, and invited written reflections asking people in pain what 'recovery' would look like in their view.  This work has already led to a number of publications and the development and publication of the Satisfaction and Recovery Index (SRI).  However, those who look at the SRI will note that there is nothing in there specifically asking about symptoms.  'Absent or manageable' symptoms was one of the primary indicators of recovery in our data, so why is it not in the SRI?  Because I wanted the SRI to be more about those other domains of life that affected health-related satisfaction.  Symptoms appeared to be adequately important as to warrant a dedicated scale.  So we've also been working on the "MSK Symptom Index" (MSI), which is meant to be a complementary tool to the SRI, both of which will ultimately serve to identify adequate recovery.  The MSI is not out in the wild yet so don't bother looking for it, but with luck it will be by the end of this year.

The symptoms on the MSI have been informed directly by our patient informants.  They identified several symptoms that were not captured on any symptom intensity scale we could find.  They will be presented below.  Interestingly, those informants frequently talked in language that would indicate that it's not necessarily the intensity of the symptoms that was the biggest factor to a sense of recovery, but how often they were experienced (frequency).  Drawing on my years as a clinician, I know that we routinely measure symptom intensity using a Numeric Rating Scale or such tool, but rarely would we capture frequency of each symptom.  And I'm not aware of a single tool that would allow measurement of both frequency and intensity of a variety of symptoms on the same tool.

So, that's what we've set out to create with the MSI.  It's been over 5 years in development now so I won't bore you, dear reader, with the finer details of its birth and refinement.  We have now been collecting data on it for several years and have some 150 response sets to work with.  As I started working on it last week, I realized that my original idea for scoring the tool wasn't working the way I expected it to.  Long story short, it's hard to know how to incorporate several constructs (number of symptoms, frequency of those symptoms, intensity/interference from those symptoms) into a single summative score.  In fact, those who know me know I prefer a unidimensional scale for clinical measurement.  But as an index, I wanted something more multidimensional for this purpose.  

I explored different ways of looking at this tool, and have now been working with a health economist to decide whether we can use the tool from a personal valuation perspective.  What does the population at large value for example, the symptom types, their frequency or their intensity?  Knowing this will help us to create unique weightings for the tool responses and create a more patient-centered scale score.  It's all rather complex and is pushing the boundaries of my knowledge (not hard).  A full standard gamble or time-trade-off study is likely in the cards, but for now I wanted to get a sense of whether it's even worth doing.  If everyone simply values symptom intensity as the primary construct, then why go any further?  With that in mind, I put a very simple online survey together last week and posted it on my Twitter account (@uwo_dwalton).  There were 4 questions, to which 20 people responded over the week.  While not a large (and by no means representative or definitive) sample, the results would suggest that there is something interesting to be explored here.  So, without further ado, here are the results of this short survey:

Question 1: Rank these symptoms from the worst (1) to the best (10):

Symptom ranks.jpg

These are sorted such that the symptom rated the worst receives the lowest score, while the symptom ranked the best receives the highest score.  From this we can see that these rankers clearly put the two pain-related symptoms, localized sharp and general dull, in a tier unto themselves as the worst of the bunch.  Weakness or giving way was in the next tier, with the remainders forming a sort of third tier, with increased sensitivity to environmental stimuli possibly forming a 4th 'least bothersome' tier.

That's interesting, but without collecting any information on the rankers it's hard to really say what this all means.  So the next questions got to the heart of the severity v frequency question.

Question 2: Please choose which of the following would be better: constant but mild (1-2/10) pain, or rare but severe (9-10/10) pain.

cons mild v rare severe

Complete wash on this one, perfect 50/50 split.  In this case the respondents were split on whether they value severity over frequency.  I had a sense this might happen, so question 3 was a bit more nuanced.  Here I reduced the gap between the intensities and the frequencies.

Question 3: Would you rather have: pain that is moderately intense (4-5/10) but often present (part of every day), OR pain that is quite intense (7-8/10) but rarely present (every few days)?

moderate vs quite intense.jpg

A clear winner here - these respondents appear to be indicating that frequency (rarely present) is more important to them than would be intensity.  Finally, I got right to the heart of the matter with question 4.

Question 4: In your mind, what is the more pressing matter when it comes to pain management: the frequency of the pain (how often you feel it) or the intensity of the pain (how severe it is when you do feel it)?

freq v intensity

A close race on this one, and plenty of caveats apply, but among these 20 mystery raters, frequency nudges out intensity 11 to 9 as the more pressing pain management issue.

At the end of the day, I don't know who these people were, this was a quick and dirty survey, and I can't confidently say that this wasn't the same person responding to the survey 20 times (though I highly doubt it).  But, assuming these were at least 20 different people, the take home from this simple little survey would suggest that while pain (or other symptom) intensity is still important, it would appear as though there is rationale for exploring pain frequency as a potentially important outcome for pain management treatment and research.  This lends support to the MSI tool we're developing, so stay tuned for updates on that.

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