Changing the Way Chronic Pain Is Categorized

The 11th edition of the International Classification of Diseases (ICD-11), which was submitted to the 72nd World Health assembly in late May 2019, includes chronic pain in the  “Symptoms, Signs or Clinical Findings” category.¹ In the case this version receives official endorsement by participating countries, these nations will begin using the updated criteria in 2022. However, chronic pain should not be viewed merely as a symptom in the way that acute pain is and should instead be classified as a disease or disorder, according to a range of experts from US and international universities who authored an editorial published in Pain Medicine.²

“Although the view of chronic pain as a disease in its own right has been debated in the past, accumulating evidence from research and clinical practice suggests that chronic or persistent pain meets the definition of a disorder, if not fully meeting the definition of disease at the moment,” noted the editorial authors. “Chronic pain results in a number of pathophysiological changes… that manifest in specific groups of symptoms and signs indicating pathology at various levels…. [and it] characteristically takes place independent from the physiological and protective role of nociception.”

The ICD-11 includes a new chronic pain classification system developed by a task force of the International Association for the Study of Pain in coordination with the World Health Organization, which includes 7 subgroups. Chronic primary pain refers to conditions that include fibromyalgia and nonspecific low back pain, in which “chronic pain may be conceived as a disease in its own right.”³

The other 6 subgroups are considered as chronic secondary pain conditions in which “pain may at least initially be conceived as a symptom.”³ These include chronic cancer-related pain, chronic postsurgical or posttraumatic pain, chronic neuropathic pain, chronic secondary headache or orofacial pain, chronic secondary visceral pain, and chronic secondary musculoskeletal pain.

Although the authors of the Pain Medicine editorial support this classification of chronic pain, they also propose that chronic pain be to the basis for a new [CM1] chapter titled, “Disorders/Diseases Related to Chronic Pain.”²