43.5% of UK population in chronic pain

How widespread is the problem of persistent pain? Speaking with Chris Smith, Alan Fayaz is a consultant in anaesthesia and pain medicine at the University College London Hospital…

Alan - Well there is actually a very specific definition for pain. It's been marked out by the International Association for the Study of Pain. And they say that pain is fundamentally an unpleasant sensory and emotional experience, but an experience that is associated with actual or potential tissue damage. So that's the other factor. So when you break that down, it can't be pleasant. It has to be unpleasant. It's a sensory experience, but there is an emotional component to it and that's what differentiates pain from other unpleasant sensations. For example, smelling a bad smell or eating bad food or listening to bad music, those are unpleasant. But because of the strong emotional component to it, that's what differentiates pain. Finally, it is usually in the context of some perceived threat, but that threat doesn't have to be necessarily visible. So I don't have to see a broken bone to believe that you have pain. It's just that it's in the context of that tissue damage that it happens.

Chris - And if we pick an average person off the street, what fraction of people at any moment in time will say they've got pain?

Alan - There is a difference between acute pain, which is pain that essentially makes sense for which there is an evolutionary basis. This is a signal from the outside world to your brain warning you that you've injured yourself. And then there's chronic pain, which is pain that's been present for the period of greater than three months. And that's no longer functional because the function of pain is to warn you, allow you to rest, distract you from the other day-to-day activities so that your body can heal and recover. But at three months, we would assume that all the healing and recovery that a body can do has happened. So at this point, we considered the pain to be dysfunctional and that's often the point at which we would call it chronic pain. And in the UK our study from 2016 suggested that somewhere in the region of between a third and half of the adult population experienced chronic pain at any one period of time.

Chris - And who does it happen to? If we look at that proportion and we ask are there any common factors or recurring factors, do you see any trends?

Alan - There are some trends. Certainly with age, there are trends. So a tendency to be more common the older you get. So when we look at populations over the age of 75, approximately two in three older adults will experience pain and a little less common if you're younger. But in some studies, some population studies in the UK as many years, one in three people under 45 years of age. So that you know, what we would consider the working population at the very least, experience chronic pain as well. But certainly a trend towards increasing likelihood of chronic pain the older you get and perhaps a little bit more common in females than it is in males. And certainly more common if there are coexisting conditions such as depression, anxiety, and social circumstances that have an impact as well. So if you are poorer, if you've had less opportunities for education, if you are unemployed, you are more likely to experience chronic pain than if you were not.

Chris - I've seen patients who say that they are very, very susceptible to pain. Is there any evidence that pain can run in families or some people are genetically more susceptible to experiencing pain in a more pronounced way acutely,

Alan - Almost certainly there is a biological component that drives pain. We know for example, that in general females, contrary to common perception, have a lower biological pain threshold than males do. But again, even when we look at that, there are psycho behavioral societal factors that may be causing that, that may be driving, that might not just be genetics, it might not just be the sex of the patient. Going back to the definition of pain, it's a sensory and emotional experience. So we know the brain is involved in all forms of pain. I'm not just talking about complex, problematic, dysfunctional, chronic pain. I'm even talking about pain in the context of injury. What we think, what we believe, what we understand has a huge impact on what we feel and the way we feel it with very different experiences. And that's why there is a strong emotional component to pain that I think genetics, it's not enough to explain the variations across the population and within an individual.

Chris - And presumably that emotional top-down control and role that's being played in pain must underpin some aspects of what, what we dub the placebo or even the nocebo effect where you expect something to happen. And so it does.

Alan - Absolutely. Absolutely. So there is a kind of therapeutic value to it. There is also potential therapeutic harm, but it extends beyond that. It is really why we focused not just on a biological approach to managing pain, but understanding the importance of sociological psychological approaches to modulating pain and really the importance of being sensitive to the environment and the context and the person's beliefs and fears. And anxieties and how they can impact on pain. Think about body aches from going to the gym. You go to the gym, you work out the next day, your body aches. But invariably you feel good about it. It's a nice feeling. You almost pack yourself on the back and you celebrate it and you go out. But if you have the flu or if you have a cold, it's almost exactly the same sensation. It's almost exactly the same feeling you have in your muscles. But certainly if you're me, you're sort of very catastrophic about it. You feel very miserable, you feel down, you take to your bed. Two very different responses to essentially the same stimulus. And again, this is reinforcing the idea of what does our belief about what's causing this, whether it's true or not, how does that drive what we feel and how can we harness this therapeutically.