Chronic primary pain: what is it and what are the medicolegal challenges?

7 Jun 2024

Primary pain is defined as pain that occurs in the absence of, or is disproportionate to, any clearly defined injury or underlying condition. It is deemed chronic when it persists for three months or more. Thus, the term chronic primary pain (CPP) encompasses a number of conditions characterised by medically unexplained pain, which are associated with a significant degree of emotional distress, functional disability and disruption of daily activities. All types of CPP are considered to be multifactorial in nature, with biological, psychological and social contributing factors. Patients can experience both primary and secondary pain (which is explained by an underlying cause) at the same time, and there may be considerable overlap of symptoms. However, it is important to recognise that these are two separate conditions and to treat them accordingly. 

There is no single test available to diagnose CPP. Instead, diagnosis is made on the basis of symptoms reported by the patient. The lack of any definite pathology means that underdiagnosis is relatively common and patients do not always receive the treatment they need. Some patients even struggle to find a doctor who believes them. When encountering a patient with possible CPP, a holistic assessment of their condition, which includes consideration of all the factors, whether physical, emotional or psychological, that might contribute to the reported pain, is required. Although chronic pain is the most obvious symptom, many patients also report functional disturbances such as dizziness, insomnia and exhaustion. There is also likely to be a history of abuse or trauma preceding the onset of symptoms, sometimes by many years, and symptoms often worsen during periods of stress. Many patients with CPP also have a psychiatric diagnosis, such as anxiety or depression. However, the temporal relationship between the two is not always clear. 

Conditions that come under the banner of CPP include fibromyalgia (FM), complex regional pain syndrome, irritable bowel syndrome (IBS), chronic migraine and chronic low back pain. The prevalence of individual conditions varies, from around 2% for FM to over 11% for IBS, but overall, the prevalence of CPP in the population is relatively high. More women than men are affected. The underlying causation of CPP remains poorly understood, although it is thought by some that alterations in the sensory processing within the central nervous system causes central sensitisation. Central sensitisation remains a controversial phenomena as there is no organic pathology that underlies it.  As such, it is argued that central sensitisation falls within the realms of theory as opposed to fact.  This lack of understanding of CPP has made the development of effective treatments difficult, and it is important that patients understand that complete resolution of their symptoms is often not possible, although significant improvement should be achievable. 

Although analgesics have been used to treat CPP for many years, there is little evidence of improvements in pain levels, psychological distress or quality of life. However, the negative effects of these medications are now widely recognised, particularly those associated with long-term use, such as overdose, dependence and withdrawal. Recent UK guidelines issued by NICE now discourage the use of analgesics for the treatment of CPP, even in the short term. Given that around 25% of the adult population in England receives a prescription for analgesics each year, many patients with CPP are likely to already be using medications such as opioids, gabapentinoids, benzodiazepines and anti-depressants. For these patients, a medication review in the form of a shared decision-making process about staged reduction and eventual deprescribing is required. 

Instead of analgesic medications, a non-pharmacological approach to the treatment of CPP is currently recommended. Physical activity is beneficial, with no specific type of exercise being associated with a greater improvement in symptoms. Therefore, patients should be encouraged to keep as active as possible, and supervised exercise programmes can also be offered where appropriate. 

In addition, many patients with CPP report significant improvements following psychological therapies such as cognitive behavioural therapy, which teaches patients to learn to accept their pain. There is also evidence that the less familiar acceptance and commitment therapy (ACT) can result in considerable functional improvement, along with a reduction in anxiety and depression. ACT is a mindfulness and behaviour change approach that emphasises psychological flexibility to enable acceptance of pain. 

Acupuncture, when delivered by a trained professional, has been associated with an improvement in quality of life that lasts for up to three months after treatment. As there is no convincing evidence of longer lasting effects, a single course only is recommended; repeated courses probably offer no additional benefit. Furthermore, acupuncture should not be used for some specific types of chronic pain, such as low back pain. However, it is unclear whether this treatment should be offered if the patient is suffering from two or more conditions where the guidelines contradict each other. In such cases, it may be left to the treating doctor to decide whether to prioritise treatment of the patient’s primary or secondary pain. 

The diagnosis and treatment of CPP remain challenging. Many patients still expect to receive analgesic medications for their condition and the recent change in treatment policy suggested by the NICE guidelines may leave doctors in the difficult position of appearing to refuse treatment. To prevent potential accusations of negligence, it is important that patients understand that current evidence shows that non-pharmacological approaches are usually more beneficial. 

Further reading: 

Harvey-Sullivan A, Higginbottom S, Round T. NICE chronic primary pain guidelines: what the busy GP needs to know. Br J Gen Pract. 2022 Apr 28;72(718):240-241. 

Nicholas M, Vlaeyen JWS, Rief W, Barke A, Aziz Q, Benoliel R, Cohen M, Evers S, Giamberardino MA, Goebel A, Korwisi B, Perrot S, Svensson P, Wang SJ, Treede RD; IASP Taskforce for the Classification of Chronic Pain. The IASP classification of chronic pain for ICD-11: chronic primary pain. Pain. 2019 Jan;160(1):28-37.