The terms of reference for the NICE guideline was to cover “all people with chronic pain (also known as persistent pain or long-term pain)”. The draft guideline uses the pain descriptions set out in the WHO’s new International Classification of Diseases (ICD-11), which comes into effect in January 2022.4,5

The ICD-11 draft version says that chronic pain is “pain that persists or recurs for longer than 3 months”. ICD-11 also introduces the term ‘chronic primary pain’, something that does not appear in ICD-10, which was last updated in 2019.6,7,8

Summarising the difference between primary and secondary pain, the International Association for the Study of Pain said: “Chronic primary pain represents chronic pain as a disease in itself. Chronic secondary pain is chronic pain where the pain is a symptom of an underlying condition.9

Other ICD-11 chronic pain categories are chronic cancer-related pain, chronic postsurgical or post-traumatic pain, chronic neuropathic pain, chronic secondary headache or orofacial pain, chronic secondary visceral pain and chronic secondary musculoskeletal pain.2,8