Posted by: notdeaddinosaur | September 26, 2010

Why Pain Cannot be a “Vital Sign”

There’s been a movement afoot for several years now to quantify pain as the so-called “Fifth Vital Sign.” It all started as a well-intentioned effort to raise the level of awareness of inadequate pain control in many patients, but has gotten way out of hand. The problem is that the word “sign” has a specific meaning in medicine that, by definition, cannot be applied to pain.

When you hear us medicos talk about “signs and symptoms” of a disease, it turns out that they are not the same thing. “Symptoms” are things the patient experiences subjectively; “signs” are things that can be observed objectively by another person. Headache is a symptom; cough is a sign. Itching is a symptom; scratch marks over a blistery linear rash are a sign. Vertigo, the hallucination of movement, is a symptom; nystagmus, the eye twitching that goes with inner ear abnormalities that can cause vertigo, is a sign. If someone other than the patient can’t see, hear, palpate, percuss, or measure it, it’s a symptom. Anything that can be perceived by someone else is a sign.

The traditional “vital signs”, four in number, are measurements of bodily functions: temperature, pulse, respiratory rate, and blood pressure. Technically one could also include weight, height, head circumference, waist circumference, urine output, etc. Vital signs are measured, two of them with specific instruments, and yield numeric results. Normal ranges are defined; values that fall outside those normal ranges are described with specific words (eg, bradycardia, tachypnea, hypothermia, hypertension).

What about pain? It is subjective by definition. If someone says they have a fever, we can measure their temperature. If it is below 99 degrees F, we can say they do not have a fever. If a patients says his or her heart is racing and we count only 80 pulse beats over one minute, he or she is not tachycardic. Not so with pain. If a patient tells us they are having pain, we are supposed to believe them (because they usually are), but we cannot measure or observe it. Sure, there are so-called “pain behaviors”, holding the affected part, writhing, moaning, etc., but as is correctly impressed upon us, the absence of those findings — those signs — does not imply the absence of pain.

It has become fashionable to ask patients to grade their pain on a scale from 1 to 10. It seems so logical. Pain is a 7; give drugs; pain goes down to a 3; success. Much as been written about this ridiculous formulation. Pain is so multidimensional that assigning a single number to it, even subjectively, is nigh impossible. I’m not saying that pain shouldn’t be assessed (serially when administering medications for it), merely that reducing it to a single numerical value is clinically ludicrous.

However you look at it, pain cannot be considered a “vital sign”; not the fifth, nor the twentieth nor the fiftieth. I agree with the importance of assessing pain. It’s right up there with the importance of assessing possible exposure to intimate violence, and the importance of asking if a patient has had a flu shot or a mammogram or a colonoscopy; ad infinitum. But trying to style “pain as the fifth vital sign” is nothing but an ill-conceived PR campaign.


  1. Allie Brosh has somewhat solved the inadequacy of the 10-point pain scale at her blog here:

  2. There’s another aspect to the subjectivity of pain, and that’s the degree of tolerance a person may have (or build up) for it.

    I’ll use myself as an example. I was injured back in 2004, resulting in two spine operations (the last a fusion) and permanent damage to the sciatic nerve in my left leg. I haven’t had a pain-free day since the injury. I’m on medication to control it, which reduces the pain to a steady 2-3 out of 10 level; but after years of operating at that level, it no longer feels like a 2-3. It’s more like a perceived 1-2, sometimes even less, simply because I’m used to it. As a result, if I suffer some painful injury, it seems to hurt me less than similar injuries in the past, because I’ve grown more accustomed to pain overall.

    Does this make sense to you as a doctor? Is it something doctors take into account when trying to measure pain, and through pain, the severity of an injury or condition?

    BTW, thanks for a very interesting blog.

  3. Great post….the pain scale was quite useful in the hospice setting, because (1) we were damned sure that these folks had legitimate pain, and it was probably gonna get worse and (2) since they were terminal and could all sorts of hot and cold running narcotics in almost unlimited quantites, there was practically no incentive to lie or exagerate. What is 50 or 100 mgs of Ms04 more when the daily dose is 800 already?

    Outside of that small subgroup, it is really a crapshoot. People lie to get drugs, and also lie to avoid taking meds. Chronic pain doesn’t have the observable behaviors that accompany severe acute pain….usually.

    So, I teach my students the party line……”pain is what the patient says it is….” But I try to let them know about differences in pain tolerance and that the scale is mostly usefull to see if a med is working or not…

  4. I suppose one observable thing may be that people who have long-term pain will hopefully at some point have seen a pain management specialist team and are likely to be on a few different non-opiate/oids as well as the stronger stuff, and will readily appreciate that taking that (say) paracetamol/diclofenac/pregabalin trio along with the MST is crucial to having decent control of their pain. The drug seekers won’t bother with any of the other stuff, they just want the Class As.

  5. What great points.

    I’m in 100% agreement with Peter. Chronic pain has also changed my personal pain scale significantly. When I say my pain is a “2 or 3”, I mean a “2 or 3” for me. If I’m experiencing a new pain or a worse pain, when I’m asked to rate it, I’ve wondered if I should try to adjust my reported pain value to meet some not chronic pain focused scale, but then the whole thing just starts to seem like an exercise in futility. It *is* subjective. Personally, I’d prefer that my medical providers understand that and at least try to interpret my pain in context with my history.

  6. The pain scale? Useless. I prefer to explain my personal scale:

    No pain

    Non-distracting pain (when I read or work, I forget about the pain)

    Distracting pain (intrudes upon my concentration)

    Really annoying pain (cannot read or work)

    Severe pain (elevated heart rate and BP, sweating; writhing in pain)

    Serial evaluations of pain after giving meds? What’s wrong with “it’s better, thank you” or “I am sorry, but I cannot feel the effect of the meds yet”?

    Oh, and _my_ narcotics negotiations are usually funnier than the normal ones.

    Dr. (to nurse): “3 mg Dilaudid, IV.”

    Me: “Can I please have Toradol instead of narcotics?”

    Dr.: “No, you cannot have Toradol. You already have proteinuria.”

    Me: “Narcotics make me loopy. I do not like being loopy.”

    Dr.: “Your blood pressure is 210 over 160. You are getting Dilaudid, 3 mg, IV.”

    Me: “Can we at least give that in 0.5 mg increments, wait a little in between, and stop when the pain is controlled?”

    To the ER doctor, the chat must have felt surreal.

  7. Actually, ALL of the vital signs have specific instruments to measure them:

    HR and RR–the second hand of a watch

    The second hand on a watch was actually invented by a physician for the purpose of taking pulses. Or that’s what I’ve heard somewhere along the line, anyway.

  8. Permit a nitpick. Isn’t a cough a symptom? Or vomiting? Or diarrhea?

  9. There are also different TYPES of pain. For example, the pain I feel when I stretch my RIGHT shoulder (wherein I had surgery to repair my torn rotator cuff two months and six days ago, but who’s counting?) while doing my OT-prescribed rehab exercises is distinctly different from the pain I feel in my LEFT shoulder (which is 13 days post cortisone shot which I had for sensations sinkingly familiar to those I had in my right shoulder pre-surgery). The right (repaired) shoulder feels sort of tight but in a weirdly good way (like finally stretching a muscle that you’ve been dying to stretch — it sorta hurts but you can tell your body is doing what it’s supposed to be doing) while the left shoulder just hurts in a really bad, painful way that makes it clear that something is not at all right.

    Like Eskimos have multiple words for snow, I’m developing multiple words for types of pain. For example, the week after my surgery — which involved shaving the bone — MY bone! — gave rise to a whole new quality of pain for me. I called it “profound” pain, and it was unlike anything I’d ever experienced. A scale of 1-10 wouldn’t begin to do it justice.

  10. […] Why Pain Cannot be a “Vital Sign” […]

  11. @Dr. Kirsch: You can hear a patient cough, and (if you are unfortunate enough) sethe vomit and diarrhea. Nausea is a symptom. The urge to cough or defecate is a symptom. How’s that for picking your nits!

  12. My son has sensory integration dysfunction. He tolerates pain that most would be screaming for morphine and rarely notices pain that would send many to the ER (except on migraines, he’s about the same as anyone who gets them!)

    Recently we’ve been fighting the combination of strep & mono (strep became resistant, long story) and when we went back to the ER with tonsils swelling and cutting off his throat ..ability to swallow and breathe (which came alarmingly close to the need for intubation)
    They asked him what his pain is. He said “7 or 8” (he was UNABLE to swallow and only able to spit)
    They nodded, made sense. I pulled up a picture of his toe that had gotten infected .. so much infection it was swollen more than 2 times it’s normal size … the infection was moving into the foot … and he only noticed because blood was messing up his socks when he ran in gym. He came to me after it had irritated him for 6 weeks. When I took him to the doctor he said his pain level was a “2”
    they saw the pic of the toe, realized what a 7 or 8 was to him … I swear the nurse went pale!

    Pain … is purely relative.


    I have often said the same thing!! I say: Pain is neither VITAL nor a SIGN.

    To be alive, you must have a blood pressure, a pulse, a respiratory rate, and a temperature…


    Thanks again!

  14. Excellent work, DinoDoc!
    Of course now JCAHO is going to label your blog a threat to patient safety for posting such blasphemy.

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