Chronic Pain has arrived in the ICD-11

Jan 17, 2019

Chronic pain affects 20% of people worldwide. Distress, demoralization and functional impairment often accompany chronic pain, making it a major source of suffering and economic burden. Yet, in the current version of the International Classification of Diseases (ICD-10), chronic pain diagnoses are not represented systematically.

In May 2019, this will change dramatically, when the World Health Organization adopts the new edition, ICD-11. ICD-11 will be the first version to include chronic pain. The chronic pain classification was developed by a Task Force of the International Association for the Study of Pain (IASP) and is based on the current scientific evidence and the biopsychosocial model. Chronic pain is defined as pain that lasts or recurs for more than three months.

A series of 10 papers published in the January 2019 issue of PAIN provide a general overview of the classification and explain the fundamental distinction of chronic primary and chronic secondary pain. 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.

Chronic primary pain is characterized by disability or emotional distress and not better accounted for by another diagnosis of chronic pain. Here, you will find chronic widespread pain, chronic musculoskeletal pain previously termed “non-specific” as well as the primary headaches and conditions such as chronic pelvic pain and irritable bowel syndrome. They are recognized as a group of chronic pain syndromes for the first time in ICD-11.

Chronic secondary pain is organized into the following six categories:

  1. Chronic cancer-related pain is chronic pain that is due to cancer or its treatment, such as chemotherapy. It will be represented in the ICD for the first time.
  2. Chronic postsurgical or post-traumatic pain is chronic pain that develops or increases in intensity after a tissue trauma (surgical or accidental) and persists beyond three months. It is also part of the ICD for the first time.
  3. Chronic neuropathic pain is chronic pain caused by a lesion or disease of the somatosensory nervous system. Peripheral and central neuropathic pain are classified here. These diagnoses are also newly represented in the ICD.
  4. Chronic secondary headache or orofacial pain contains the chronic forms of symptomatic headaches (those termed primary headaches in the ICHD-3 are part of chronic primary pain) and follows closely the ICHD-3 classification. Chronic secondary orofacial pain, such as chronic dental pain, supplements this section.
  5. Chronic secondary visceral pain is chronic pain secondary to an underlying condition originating from internal organs of the head or neck region or of the thoracic, abdominal or pelvic regions. It can be caused be persistent inflammation, vascular mechanisms or mechanical factors.
  6. Chronic secondary musculoskeletal pain is chronic pain in bones, joint and tendons arising from an underlying disease classified elsewhere. It can be due to persistent inflammation, associated with structural changes or caused by altered biomechanical function due to diseases of the nervous system.

In two further papers of the series, the Task Force addresses further important issues. Together with representatives of the International Society of Physical and Rehabilitation Medicine (ISPRM) they explain the functioning properties of chronic pain that crosslink the diagnoses to the International Classification of Functioning, Disability and Health (ICF). The Task Force aimed at developing a classification useful in specialized setting as well as in primary care contexts. Therefore, the series concludes with a discussion of the applicability of the new classification to primary care.

It is the hope of the Task Force that the inclusion of the chronic pain conditions in the ICD-11 will further the recognition of chronic pain as a health problem in its own right and contribute to improved access to adequate pain treatment for persons with chronic pain worldwide.

 

 

--Antonia Barke (Marburg University) coordinates the IASP Working Group on the Classification of Chronic Pain.