I recently got a review back from a manuscript I submitted on the usefulness of pressure pain threshold testing in people with acute neck pain. One of the reviewers' commented on my use of the Numeric Rating Scale for evaluating pain intensity, with specific mention of the descriptive anchor I use, and have been using for years, to operationalize a '10' on that scale. I use 10 means Terrible Pain. This reviewer, quite correctly I should say, indicated that Terrible Pain is not a standard anchor for the NRS and asked me to justify its use. I haven't got to it yet, busy as I am currently with teaching and grant applications, but I thought I would take a few minutes to see if we could get some discussion going here on what a 10 should mean.
To start this discussion, I'm going to offer up a segment from an essay that was written by an adolescent patient with chronic pain, and sent to me from a colleague who had been treating this patient for some time. It's an incredibly insightful piece, and I wish I could share it all but don't have permission to do so. Here's a short snippet though:
Let’s say 10 is the worst pain you can imagine, as I have been told many times to do. OK so 10 is the worst pain I can think of. 10 is being burned, while being run over by a train, while having your hair pulled, while watching a puppy die, while….you see where I’m going? If 10 is the epitome of all pain then any pain you may be experiencing at the time seems to be minor in comparison. You may rate your pain as a 2 or a 3, then the person who has asked the question thinks that your pain is not that bad. It is somewhat ridiculous to ask someone to compare what he or she is experiencing to the limitlessness of his or her imagination.
Ok, 10 stands for the worst pain you have ever felt, this was the alternative I was presented with. Well then I guess worst pain I have ever felt was getting a nail through my hand, but then again I was 8 at the time. I was in perfect health and it seemed to me at the time a horrific experience when I skinned my knee. I’m 15 now my pain threshold has gone through the roof, I’ve been in pain for 2 years, and so is it correct to compare my immediate pain to a 7-year-old memory of an event? Honestly I would not trust any memory I have from yesterday, I certainly would not claim accuracy to one that old.
For those familiar with the NRS, you know this patient has pretty much hit the nail on the head. Neither 'worst pain you can imagine' nor 'worst pain you have ever felt' are particularly useful.
Worst pain you can imagine: Depending on the vividness of one's imagination, this could get pretty hairy. Would I choose physical pain or emotional pain as the worst I could imagine? Guess what? As an assessor, you'll never know.
Worst pain ever: Unless the assessor possesses an intimate knowledge of the patient's previous experiences with pain, a response to this question is virtually impossible to interpret. Perhaps this is in fact the worst pain the person has ever felt, even though it's relatively minor in the grand cosmos of pain experiences.
Worst pain possible: Hmm, another imagination-based option. Same problems as above.
Pain at the level for which you would have to go to the hospital: I've heard this one bantered around before, or some variant thereof. The biggest problem with this is that you've added an extra layer of cognitive interpretation here: that of the person's belief in the medical system to control their pain. When they give a low score, is that because they're not feeling intense pain, or because they don't have faith in medicine to control the pain they're feeling and hence wouldn't want to go to the hospital? Don't know unless you explore, and that gets away from the simple elegance of the scale.
The problem here is that pain intensity ratings are far and away the most common method of assessing pain, both clinically and for research purposes. They should be providing guidance for treatment decisions, prognosis and evaluation over time. Yet, with anchors like the ones that have been traditionally used, problems with interpretation abound. Here's a simple example: the WHO analgesic ladder would suggest that front-line therapy for intense pain are high-potency narcotics. But, if you've used the anchor 'worst pain ever', and this paper cut is indeed that patient's worst pain ever, does that mean we move right to morphine? Doesn't make sense.
If you're lucky, you've had a chance to read the Hyperbole and a Half blog about experiences with the Wong-Baker face scale, and a suggested revision. It's a tongue-in-cheek take on the problem I'm discussing here. I also personally like the Scrubs clip on using the Wong-Baker, in a completely inappropriate manner of course. So, what is a '10'? As I mentioned, I've been using Terrible Pain, to give it an anchor that I might have at least some chance of being able to interpret. It's subjective no matter how you look at it, but pain is an intensely personal experience and you can't separate the person from their pain. I could certainly see other descriptors in place of terrible, such as excruciating, torturing, or something else that implies both extreme physical and emotional distress. Another great option I've heard, and I wish I could remember where I heard it (perhaps someone can help me here) is this: a 10 is pain so bad you're afraid you'll die, and an 11 is pain so bad you're afraid of living. That's extreme, but that's the kind of thing an anchor should be - so extreme that people very rarely choose it.
So for now, I like Terrible Pain. It's been working for me in both a clinical and research sense for years. But I'd love to hear your opinions. What do you think a 10 should be? Leave a comment below.