Pain Centre progress

Article taken from Arthritis Today | Summer 2015 | No 168

Chronic pain – the kind of pain that doesn’t go away or comes and goes in varying degrees – is highly complex.

Unlike acute pain, which has an obvious cause, such as toothache or a broken bone, the causes of long-term pain, as found in osteoarthritis, for example, have always been challenging for scientists and researchers to understand.

For example, two people with osteoarthritis of the knee may have exactly the same amount of cartilage degeneration in their knees, as revealed on x-rays. However, both may experience completely different levels of pain. So while one person might carry on and cope with taking occasional painkillers, the other will be waiting for a knee replacement.

This curious phenomenon is something that researchers at our pain centre are puzzling over, because understanding the different pain pathways and how the brain processes chronic pain is clearly crucial in developing new ways to tackle it.

Puzzling over pain 

Over the course of their first five years the research team made some interesting discoveries. When the centre was first established, it was often thought that pain from osteoarthritis was simply the result of damage to a joint. The research team have made a major contribution to changing the way people think about the pain of osteoarthritis, recognising that it’s the result of several interacting factors.

They've identified that there are two broad sub-groups of people with knee osteoarthritis, whose pain appears to be processed in very different ways. 

1. In one group, the pain is directly transmitted from the joint. The team are currently looking at new potential pain-relieving drug targets for this type of pain.
2. In the other group, signals from the joint are amplified and diverted into pain pathways as they travel through the spine. The research team has helped to discover that psychological distress, such as low mood and anxiety experienced by some people with osteoarthritis, is linked to the way the central nervous system processes these pain signals. 

"Different people might respond differently to different drugs at different times."Centre director Professor David Walsh

Explains centre director Professor David Walsh: “Our findings now lead us to think that people with knee osteoarthritis might move between these two sub-groups during the development and progression of their osteoarthritis, and therefore effective treatments will differ between early and late disease.

“We’ve demonstrated that arthritis pain is many different things to different people and at different times.

“We’ve surveyed more than 9,000 people in the Nottingham area and within this population we’re now able to define the different knee pain characteristics and groups of people with arthritis pain.”

The right treatment at the right time

This idea of putting patients into sub-groups depending on their profiles or characteristics rather than treating them in a one-size-fits-all fashion is a concept known as ‘stratification’ which has been covered in previous editions of Arthritis Today.

It’s a concept that started with cancer specialists and is currently being developed in rheumatology circles for rheumatoid arthritis patients. It basically means that instead of treating patients as all having the same disease and taking a one-size-fits-all approach to their treatment, they’re given the right drug or treatment that will work best for them, at the best time and at the most effective dose. 

Professor Walsh points out that currently there are dozens of ways to treat osteoarthritis, from drugs to lifestyle changes to surgery.

“Being able to get the right treatment to the right patient for the right problem at the right time is one of the challenges we have in medicine,” he acknowledges.

“At the moment what treatment you get depends on the person you go to see – a physiotherapist will give you physiotherapy; a GP is likely to give drugs; and a surgeon a may suggest a new knee joint. It risks being a lottery. If we give better advice to people on what they’re likely to get benefit from for their particular problems, you’d get away from that.”

Pain centre colleague Professor Mike Doherty concurs. “Everyone recognises that patients should have an individual assessment when they see a health professional so they can be assessed both psychologically and physically, but often this doesn’t happen,” he says. Often they’re just given paracetamol and told if it works not to come back.

"In the future patients can be offered the treatments that might prevent their pain getting worse.”Professor David Walsh 

“The idea of a management plan to meet the individual characteristics of the person is steeped in evidence-based philosophy. And we need to try to extend that into a practice guide for GPs.”

Although the development of stratified medicine as a means of treating people with osteoarthritis would appear to be a few years down the line, Professor Walsh is clear about the centre’s aims for the next five years. 

“We’ll have a better understanding of the nature and consequences of how the pain of arthritis changes in people with knee osteoarthritis, and find ways to predict in whom pain is likely to progress,” he says. “So in the future patients can be offered the treatments that might prevent their pain getting worse.” 

Mood and arthritis 

As well as concentrating on basic science and laboratory-based research, pain centre researchers are now developing their programme of clinical studies involving patients. 

They’re running a small feasibility study looking at psychological distress experienced by some people with osteoarthritis and whether the antidepressant duloxetine can reduce pain in this subgroup of patients.

It’s known that the outcome of surgery can depend on patients’ mood, and those with depression and anxiety have worse outcomes.

So the team is also running a feasibility study called HAPPiKNEES to see if offering cognitive behavioural therapy to people with low mood and anxiety before they undergo knee replacement surgery improves their pain outcomes after the operation, and make them more likely to benefit from post-op rehabilitation.

Arthritis Today will keep you up to date with developments.

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Our pain centre was launched in 2011 with £5.5m from the charity and the University of Nottingham. It received a further five years of funding of £2.5m from us in 2014.

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