Redefining the Way Chronic Pain Is Categorized

The 11th edition of the International Classification of Diseases includes chronic pain in the “Symptoms, Signs or Clinical Findings” category.

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

To gain additional insights regarding this issue, Clinical Pain Advisor interviewed co-author Jianguo Cheng, MD, PhD, professor of anesthesiology, director of the Cleveland Clinic Multidisciplinary Pain Medicine Fellowship Program, and president of the American Academy of Pain Medicine, and Timothy R. Deer, MD, DABPM, FIPP, president and CEO of the Spine and Nerve Center of The Virginias, and clinical professor of anesthesiology and pain medicine at the West Virginia University School of Medicine.

Clinical Pain Advisor: How do you explain  that pain is still considered a symptom rather than a disorder?

Dr Deer: Pain is such a common occurrence in a heterogeneous number of conditions that it is often associated with many diseases of aging, thus it is thought of as a symptom.

Dr Cheng: Acute pain is typically part of the warning system that informs the body of injury or disease and is therefore physiologic and protective. Because most individuals have experienced acute pain that resolves in most cases after the inciting injury or disease heals, it is not uncommon for people to hold the belief that chronic pain is just like acute pain as a symptom of other diseases or injuries. However, chronic pain typically loses its protective function and becomes harmful to one’s functionality, productivity, well-being, and quality of life.

Many pain syndromes exist without clear inciting injury or disease. Thus, chronic pain could be a category of disease in its own right. It often has biopsychosocial determinants that need to be treated in such a model of care to achieve better outcomes. This  is not widely known even among health care professionals, primarily due to the very limited pain education throughout the continuum of professional training for most health care providers, let alone for patients and the public.

Clinical Pain Advisor: For patients, what are some of the potential benefits of categorizing chronic pain as a disease rather than as a symptom?

Dr Deer: It is a complicated discussion. There is a need for a separate specialty of pain medicine, because it is currently very disorganized. For example, a physician with very little training can offer their services to the public and suggest they are a pain physician. This can be dangerous and was a major factor in the pill mill problem. Chronic pain can be viewed as a disease, but this would require close coordination of a nationwide task force and a separation of interventional pain specialists and noninterventional specialists, with a need to work together in a multimodal method of patient care.

Dr Cheng: Categorizing chronic pain as a category of disease would recognize the legitimate complaints and the physical and emotional pain of these patients. It would also help  reduce the stigma of chronic pain that is so commonly encountered in health care settings, in the workplace, at home, and in society.

Clinical Pain Advisor: What are some of the benefits that such a classification of chronic pain would bring to pain medicine physicians and the field at large?

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Dr Deer: It would standardize training and make it much easier for patients and insurers to understand who is delivering care and training. This could also lead to national registers to follow outcomes.

Dr Cheng: With the understanding that chronic pain can be a category of disease, we can better study its prevalence, epidemiology, ideology, classification, mechanisms, assessment, diagnosis and differential diagnosis, and safe and effective therapeutic strategies and treatment methodologies. Mechanism-guided and evidence-based therapies for specific chronic pain syndromes and diseases can be developed, and treatment outcomes can be monitored, compared, and improved.

Only then can healthcare providers break the habit of treating pain as a symptom of disease — often with the overuse of painkillers — and embrace the concept of the biopsychosocial model, using a multidisciplinary and multimodal approach to patient-centered pain care. Ultimately, this would benefit patients by better treating their pain and improving their functionality, productivity, and quality of life.

Clinical Pain Advisor: What are additional takeaways or remaining needs in this area?

Dr Deer: It is important that all specialties with a focus on pain treatment create a more collaborative effort — this has been a major impediment to the process. I would call for a national summit of validated and concerned societies to create a plan to create the specialty of pain medicine — with an interventional track that requires additional time in training — and a focus on chronic pain as a disease.

Dr Cheng: The Health and Human Services Pain Management Best Practices Inter-Agency Task Force has made strong recommendations about recognizing chronic pain as a category of disease in its draft report to the US Congress. It has also made specific recommendations on professional training and education, as well as on educating patients, their families, and the public. Congress has allocated substantially more research funding to the National Institutes of Health for pain and substance use disorder research.

The recently formed National Academy of Medicine Action Collaborative on Countering the U.S. Opioid Epidemic has designated a specific Health Professional Education and Training Working Group that is charged with finding ways to improve education, accreditation, certification, and credentialing processes regarding pain and substance use disorder throughout the continuum of professional education in all relevant health professions.  


1. World Health Organization. ICD-11 is here! Accessed  April 30, 2019.

2. Lu Y, Cheng J, Han JS, et al. A proposal to add a new dedicated chapter in ICD-11: disorders related to chronic pain [published online April 6, 2019]. Pain Med.  doi:10.1093/pm/pnz060

3. Treede RD, Rief W, Barke A, et al. Chronic pain as a symptom or a disease: the IASP Classification of Chronic Pain for the International Classification of Diseases (ICD-11). Pain. 2019; 160(1):19-27.

This article originally appeared on Clinical Pain Advisor