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Chronic Primary Pain vs Chronic Secondary Pain – what is the difference?

I have been working as a patient advocate in chronic pain for many years. As I have learned about chronic pain, the science, and the neuroscience of pain, I have realised that a huge part of the problem, and a reason for the untreated pain epidemic we are now experiencing in Australia, is as simple as definitions. 

It has been my driving force to correct the record and teach people the difference between the types of chronic pain and why and how the term ‘chronic pain’ has been hijacked, and the damage that has done to people living with constant, severe pain.

What is chronic pain

The term ‘chronic pain’ is an umbrella term. It is a phrase with such broad meaning as to have no practical meaning at all.  If a person has ‘chronic pain’ this tells you nothing about them, except there is pain. They may have a range of diseases or injuries, or no physical cause for pain at all.  There is no one treatment path, and a diagnosis of ‘chronic pain’ is just the starting point, not a diagnosis at all.

There are many types and causes of chronic pain, but the dominant definition most often quoted is ‘pain that persists beyond the normal healing time’ or pain for which no structural cause can be found.

But this definition applies to only ONE type of chronic pain – chronic primary pain.   There is another common kind of chronic pain – chronic secondary pain.  Unfortunately, in Australia in 2023, many allied health professionals and even some GPs do not understand the difference.  They have not been taught the difference, or why it matters.  This article will aim to explain.

Chronic Primary Pain

Chronic primary pain is pain where no structural, pathological or biological cause can be found for the pain. The common definition is pain that lasts for longer than 12 weeks, and persists beyond the normal healing time of, or is out of proportion to, the original injury or disease.

It’s also referred to as ‘non-specific pain’ or ‘nociplastic pain’.

Chronic primary pain is associated with high levels of distress and people with primary pain are highly anxious, and/or depressed about their pain. 

They are often high care seekers, looking for a firm diagnosis or someone to ‘fix’ their pain. They are commonly convinced that there is something seriously wrong with their body, and continue to consult doctor after doctor, getting test after test, all of which come back normal.  They may have received low quality care, poor advice, or misinterpreted what their doctor told them, leaving them with maladaptive thoughts and beliefs around pain.  These thoughts and beliefs have led to poor choices.

They have poor self-efficacy and low health literacy. 

They are afraid of exercising, or movement, for fear of causing damage and pain. Consequently, they become deconditioned, and lose muscle mass and strength.  When they do try to move, their muscles have become stiff and sore, which they interpret as pain, which only reinforces their fear of movement and their belief that exercise is harmful.    

People often give up work, stop socialising, and stop engaging with their communities.   This causes social isolation and loneliness which compounds their distress, anxiety and depression.

By definition, chronic primary pain is mild to moderate, but the person’s distress, anxiety and fear amplifies their perception of pain.

Chronic primary pain is caused by a malfunctioning or over-sensitised nervous system via a process called central sensitisation. Central sensitisation turns up the volume on pain, and people with primary pain have a lower pain threshold and lower pain tolerance.  It has been compared to an overly sensitive car alarm that goes off at the slightest touch. In chronic primary pain, the brain ‘learns’ pain via a process called neuroplasticity, which is the mechanism by which the brain changes and adapts.  Thankfully, neuroplasticity works both ways, and with proper therapy, the volume knob can be turned back down.  After treatment, some people become completely pain free, and but most still live with some pain, usually mild or intermittent pain.

In chronic primary pain, ‘pain’ is not really the core problem, anxiety, fear and maladaptive thoughts and behaviours are. 

Opioids should never be prescribed for chronic primary pain.

Role of Pain Science Education

Pain science education was designed as a therapy to reduce chronic primary pain, but it is only effective in combination with other therapies. It was originally proposed as a treatment in its own right, but the science shows that pain science education does not reduce pain, or disability, in and of itself.  Most physiotherapists see pain science education as an adjunct therapy.

However, pain science education is a very popular therapy with some, that may empower people to engage with rehabilitation.  Pain science education teaches that pain is an output of the brain that can be changed via a combination of education on the neurobiology of pain and reassurance.   People are taught that ‘hurt does not equal harm’ and that they are ‘safe to move’ which reduces their fear and anxiety.  Graded exercise teaches them to start exercising slowly and safely, and gradually increase the length and intensity of exercise sessions. 

Pain science education was only EVER designed as an explanation and treatment for pain that persists without a medical cause – chronic primary pain. It should NOT be considered a treatment for chronic secondary pain. Every study on pain science education recrutied people with mild to moderate pain, and excluded those with pathology. That is, they excluded people with chornic secondary pain. But hey keep that very quiet and sold this treatment as a panacea for ALL ‘chronic pain’. This was misleading at best and outright deceptive at worst.

In chronic primary pain, pain is essentially a fear response. Reduce the fear and you reduce the pain, so the theory goes.  Through education, people realise their pain is not dangerous, that exercise is not harmful, and that they are capable of self-managing their pain. 

Chronic Secondary Pain

Chronic Secondary pain, on the other hand, IS caused by structural/pathological/biological causes.  A biological process, injury or inflammation is the predominant cause of chronic secondary pain.  It is called ‘secondary’ pain because it is secondary to a disease process, or injury.  Cancer is secondary pain, arthritis, MS, Parkinson’s, adhesive arachnoiditis, there are many diseases that cause chronic secondary pain. 

Chronic secondary pain is nociceptive or neuropathic and to treat this pain, the underlying cause must ALSO be treated.  Chronic secondary pain is like acute pain that happens every day, and can be mild, moderate or severe. 

All pain is biopsychosocial, but in chronic secondary pain, psychosocial factors have less influence than in chronic primary pain. Psychosocial influences on pain must still be addressed, but unlike chronic primary pain, it is impossible to ‘cure’ chronic secondary pain with psychosocial treatments alone. 

In chronic secondary pain, especially where pain is severe, biomedical treatments are very often necessary.  Biomedical treatment is the ‘bio’ in the biopsychosocial model and includes surgeries, procedures, and medications.

For example, a person with rheumatoid arthritis will be on disease modifying medications and may have procedures and surgeries to correct joint damage caused by the disease, which then reduces their pain. For the best outcome and quality of life, they will also exercise regularly, eat a healthy diet, maintain a healthy body weight, and address any mental health issues. Sometimes, the pain cannot be treated fully with these methods, and if pain is severe and disabling, pain medications are also an essential treatment to reduce pain.  These can be simple analgesics, nsaids or opioids.  When pain is severe, opioids are often the only effective treatment for chronic secondary pain.

Treatment for chronic primary and secondary pain

It should be obvious that chronic primary pain and chronic secondary pain are very different. They have different causes, and most importantly, require very different treatments.

Unfortunately, in Australia in 2023, allied health professionals, and even many public pain clinics, are treating all ‘chronic pain’ as if it were chronic primary pain.  They believe that the root cause of ALL chronic pain is fear avoidance, anxiety and depression and lack of exercise, which is very wrong.

Every website, every seminar, every flyer, and most research studies refer to ‘chronic pain’ when they mean chronic primary pain.

Obviously, this leaves people with chronic secondary pain without effective pain treatment.  People who have progressive, painful, incurable diseases who were stable and doing well on long term opioid therapy have been force tapered off their long-term opioid therapy, to their great harm. 

Instead, they are given psychological treatments, pain science education, and physiotherapy which does not address the biological aspect of their pain, nor treat it effectively.  In short, people who live with constant, severe, pain are being given treatments that are only appropriate for chronic primary pain, or mild to moderate pain.   

It is a myth that tapering opioids does not result in increased pain.  That idea is based on one flawed study that has been roundly discredited. The majority of studies show exactly what common sense tells you, that tapering opioids most often results in increased pain, increased disability and lower quality of life.

Yet forced tapers continue.

Recent large-scale studies also show that tapering, especially forced tapering, is associated with overdose, suicidal ideation and death. The evidence shows that it is far safer to maintain people on long-term opioid therapy.

Yet forced tapers continue.

There are no alternatives to opioids for severe chronic secondary pain at this time.  Physiotherapy, pain science education, psychological treatments are only effective on mild to moderate pain, and pain science education was only ever intended for the treatment of chronic primary pain.

Opioids are very often the only thing that reduces severe pain enough so that a person living with severe chronic secondary pain can have any quality of life.  Opioids reduce pain enough so that people can work, take care of their families, exercise and engage with their communities.   And when well monitored, as opioid therapy is in Australia, long term opioid therapy IS safe and effective.  There are now many high quality, large scale, recent studies that show this.

But that message is not getting through.  Those studies are not being publicised or promoted in the media.  Health care professionals are taught that opioids are dangerous and ineffective, and people must be tapered. By force, if necessary.

This leaves people with serious, progressive, disabling, painful diseases who are in severe, daily pain, without effective pain treatment. Because psychosocial treatments cannot treat pathological/biological/structural pain, any more than opioids can treat psychosocial pain.

When a person has chronic secondary pain, their pain is NOT caused by poor coping skills, poor choices, or maladaptive thoughts and beliefs around pain.  Psychosocial influences may have an effect, but they are not the cause of the pain and very often have very little influence on pain severity.  Particularly if the person has been living with chronic secondary pain for many years.

Psychologically, if a person is distressed, anxious, or frightened, their pain may be amplified by their emotions.  If you have two people with identical injuries, say you have two people with a broken femur, the one who is calm, unafraid and positive may experience less pain, or cope better with the injury.  The person who is hysterical, screaming and crying may experience more pain.  That does NOT mean emotions are the cause of the pain, the pain is still caused by the injury, the broken femur.  And the pain cannot be treated without treating the broken femur. 

While you may be able to reduce, or even cure, chronic primary pain with education and reassurance, you cannot explain away a tumour or reassure away a severed limb.   Yet this is exactly what physiotherapists are trying to do, when they give pain science education as a treatment to a person living with chronic secondary pain.

People with chronic secondary pain can have excellent mental health, not be distressed or anxious or depressed, exercise daily, have no maladaptive thoughts and beliefs around pain, understand pain neuroscience, engage in meditation and live mindfully, have excellent self-efficacy and health literacy,  AND STILL live with constant, severe pain.

Because their pain is caused by a biological/pathological/structural process.  NOT fear or anxiety or poor coping skills or lack of education, or poor choices.  A biological process is the root cause of their pain.

All Pain is Biopsychosocial

All pain is biopsychosocial.  The first step in treating any chronic pain is a complete biopsychosocial assessment.  Pain is individual.  Two people can have the same diagnosis, or injury, and have very different experiences of pain.    There is NO one size fits all for chronic pain.  

Yet that is what is happening.  All pain is being treated as chronic primary pain, even the term ‘chronic pain’ is being used to describe only chronic primary pain. People living with chronic secondary pain are being ignored, and not allowed access safe and effective pain treatments.

All people are herded into pain science education courses, regardless of diagnosis or pain severity, before they can even see a doctor.  Some pain clinics require that the person self-taper their pain medications before they will be seen.

This leaves people living with progressive, painful diseases without effective pain treatment. And these people are amongst the most vulnerable in our community.  These are the people living with the most severe chronic pain, people who are genuinely disabled by physical issues, not psychosocial ones.

Some health professionals stigmatise people who rely on long term opioid therapy.   Some insist that people on long term opioid therapy have an opioid use disorder.  Or believe that they are not willing to ‘do the hard work’, that they ‘want a quick fix pill’.  This is highly stigmatising and borne of ignorance on the health care professional’s part.  They have learned the biopsychosocial model, but they were only taught half of it – the psychosocial half.

We must not forget the ‘bio’ in the biopsychosocial model. Its there for a reason! All health care professionals need to understand the difference between chronic primary pain and chronic secondary pain, and how the treatment differs.

Diabetes is often compared to chronic pain, usually comparing insulin to opioids in an effort to explain dependence vs addiction. The analogy holds in terms of chronic primary and secondary pain. Imagine if only one type of diabetes were treated? What if those with type 1 diabetes were treated with the medications and lifestyle changes that type 2 diabetics are often treated with? What if, instead of insulin, they were told to lose weight and exercise?

People with type 2 diabetes would die.

Type 1 and Type 2 are not the same disease, they are very different diseases, with very different treatments. Just like chronic primary pain and chronic secondary pain.

In fact, when speaking of diabetes, the first question is almost always “Type 1 or type 2?”

This is what needs to happen in chronic pain treatment.

Its time to STOP referring to ‘chronic pain’ without clarification. ‘Chronic Pain’ is a meaningless term; chronic pain is either primary or secondary.  Before pain can be treated, it must be determined whether the pain is primary or secondary. Although there can be elements of central sensitisation in people with chronic secondary pain, it is secondary pain if the pain is predominently caused by pathological/structural/biological factors. If the pain is predominently caused by central sensitistaion, it is chronic primary pain. There are validated instruments and tools to determine the level of central sensitisation, yet they are rarely used in clinical practice. It is just assumed that chronic pain is cause by central sensitistation, leading to low quality and ineffective treatment. This has to stop.

Researchers need to stop refering to ‘chronic pain’ in their work and clarify what type of pain they are discussing. Some already do, the more ethical ones, though its usually buried in the text. And they need to stop promoting treatments for chronic primary pain as treatments for all chronic pain. This is fallacious at best and fraudulent at worst.  And pain management programs, seminars, webinars, books etc that people are profiting from, need to be honest in what kind of pain they can and cannot treat.

Non-specific pain, psychosocial pain, nociplastic pain, these are all terms for chronic primary pain.

Nociceptive pain, and neuropathic pain are chronic secondary pain.

Most of all, each person must be treated as an individual, and chronic pain, primary or secondary, must be treated with empathy, compassion and most of all, the correct treatment.

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