IASP Classification of Chronic Pain for the ICD-11

This is a series of PubMed articles (in numerical order) dealing with the classification and coding of chronic pain in the upcoming 11th edition of the International Classification of Diseases.

Getting this right by creating the right descriptions for each type of pain is critical for meaningful diagnoses and pain research.

Chronic pain as a symptom or a disease: the IASP Classification of Chronic Pain for the International Classification of Diseases (ICD-11). – PubMed – NCBI –  Jan 2019   

Chronic pain is a major source of suffering. It interferes with daily functioning and often is accompanied by distress. 

Yet, in the International Classification of Diseases, chronic pain diagnoses are not represented systematically. The lack of appropriate codes renders accurate epidemiological investigations difficult and impedes health policy decisions regarding chronic pain such as adequate financing of access to multimodal pain management. 

In cooperation with the WHO, an IASP Working Group has developed a classification system that is applicable in a wide range of contexts, including pain medicine, primary care, and low-resource environments. 

Chronic pain is defined as pain that persists or recurs for more than 3 months. In chronic pain syndromes, pain can be the sole or a leading complaint and requires special treatment and care. 

In conditions such as fibromyalgia or nonspecific low-back pain, chronic pain may be conceived as a disease in its own right; in our proposal, we call this subgroup “chronic primary pain.”

In 6 other subgroups, pain is secondary to an underlying disease: 

1. chronic cancer-related pain, 
2. chronic neuropathic pain, 
3. chronic secondary visceral pain, 
4. chronic posttraumatic and postsurgical pain, 
5. chronic secondary headache and orofacial pain, and
6. chronic secondary musculoskeletal pain. 

These conditions are summarized as “chronic secondary pain” where pain may at least initially be conceived as a symptom. 

Implementation of these codes in the upcoming 11th edition of International Classification of Diseases will lead to improved classification and diagnostic coding, thereby advancing the recognition of chronic pain as a health condition in its own right.

The IASP classification of chronic pain for ICD-11: chronic primary pain. – PubMed – NCBI

This article describes a proposal for the new diagnosis of chronic primary pain (CPP) in ICD-11.

Chronic primary pain is chosen when pain has persisted for more than 3 months and is associated with significant emotional distress and/or functional disability, and the pain is not better accounted for by another condition. 

As with all pain, the article assumes a biopsychosocial framework for understanding CPP, which means all subtypes of the diagnosis are considered to be multifactorial in nature, with biological, psychological, and social factors contributing to each. 

Unlike the perspectives found in DSM-5 and ICD-10, the diagnosis of CPP is considered to be appropriate independently of identified biological or psychological contributors, unless another diagnosis would better account for the presenting symptoms. 

Such other diagnoses are called “chronic secondary pain” where pain may at least initially be conceived as a symptom secondary to an underlying disease. 

The goal here is to create a classification that is useful in both primary care and specialized pain management settings for the development of individualized management plans, and to assist both clinicians and researchers by providing a more accurate description of each diagnostic category.

The IASP classification of chronic pain for ICD-11: chronic cancer-related pain. – PubMed – NCBI

Worldwide, the prevalence of cancer is rising and so too is the number of patients who survive their cancer for many years thanks to the therapeutic successes of modern oncology. 

One of the most frequent and disabling symptoms of cancer is pain.

In addition to the pain caused by the cancer, cancer treatment may also lead to chronic pain.

Despite its importance, chronic cancer-related pain is not represented in the current International Classification of Diseases (ICD-10). 

This article describes the new classification of chronic cancer-related pain for ICD-11. 

Chronic cancer-related pain is defined as chronic pain caused by the primary cancer itself or metastases (chronic cancer pain) or its treatment (chronic postcancer treatment pain).

It should be distinguished from pain caused by comorbid disease. Pain management regimens for terminally ill cancer patients have been elaborated by the World Health Organization and other international bodies. 

An important clinical challenge is the longer term pain management in cancer patients and cancer survivors, where chronic pain from cancer, its treatment, and unrelated causes may be concurrent. 

This article describes how a new classification of chronic cancer-related pain in ICD-11 is intended to help develop more individualized management plans for these patients and to stimulate research into these pain syndromes.

The IASP classification of chronic pain for ICD-11: chronic postsurgical or posttraumatic pain. – PubMed – NCBI

Chronic pain after tissue trauma is frequent and may have a lasting impact on the functioning and quality of life of the affected person. Despite this, chronic postsurgical and posttraumatic pain is underrecognised and, consequently, undertreated. 

It is not represented in the current International Classification of Diseases (ICD-10). 

This article describes the new classification of chronic postsurgical and posttraumatic pain for ICD-11. 

Chronic postsurgical or posttraumatic pain is defined as chronic pain that develops or increases in intensity after a surgical procedure or a tissue injury and persists beyond the healing process, ie, at least 3 months after the surgery or tissue trauma.

In the classification, it is distinguished between tissue trauma arising from a controlled procedure in the delivery of health care (surgery) and forms of uncontrolled accidental damage (other traumas).

In both sections, the most frequent conditions are included. This provides diagnostic codes for chronic pain conditions that persist after the initial tissue trauma has healed and that require specific treatment and management.

It is expected that the representation of chronic postsurgical and posttraumatic pain in ICD-11 furthers identification, diagnosis, and treatment of these pain states. 

Even more importantly, it will make the diagnosis of chronic posttraumatic or postsurgical pain statistically visible and, it is hoped, stimulate research into these pain syndromes.

The IASP classification of chronic pain for ICD-11: chronic neuropathic pain. – PubMed – NCBI

The upcoming 11th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD) of the World Health Organization (WHO) offers a unique opportunity to improve the representation of painful disorders. For this purpose, the International Association for the Study of Pain (IASP) has convened an interdisciplinary task force of pain specialists. 

Here, we present the case for a reclassification of nervous system lesions or diseases associated with persistent or recurrent pain for ≥3 months.

The new classification lists the most common conditions of peripheral neuropathic pain: 

• trigeminal neuralgia,
•  peripheral nerve injury, 
• painful polyneuropathy, 
• postherpetic neuralgia, and 
• painful radiculopathy. 

Conditions of central neuropathic pain include pain caused by spinal cord or brain injury, poststroke pain, and pain associated with multiple sclerosis. 

Diseases not explicitly mentioned in the classification are captured in residual categories of ICD-11. Conditions of chronic neuropathic pain are either insufficiently defined or missing in the current version of the ICD, despite their prevalence and clinical importance. 

We provide the short definitions of diagnostic entities for which we submitted more detailed content models to the WHO. 

Definitions and content models were established in collaboration with the Classification Committee of the IASP’s Neuropathic Pain Special Interest Group (NeuPSIG). 

Up to 10% of the general population experience neuropathic pain.

The majority of these patients do not receive satisfactory relief with existing treatments.

A precise classification of chronic neuropathic pain in ICD-11 is necessary to document this public health need and the therapeutic challenges related to chronic neuropathic pain.

adequate coding, as well as patient management through better diagnostic classification.

The IASP classification of chronic pain for ICD-11: chronic secondary headache or orofacial pain. – PubMed – NCBI

This article describes chronic secondary headache and chronic orofacial pain (OFP) disorders with respect to the new International Classification of Diseases (ICD-11). 

The section refers extensively to the International Classification of Headache Disorders (ICHD-3) of the International Headache Society that is implemented in the chapter on Neurology in ICD-11. 

The ICHD-3 differentiates between

• primary (idiopathic) headache disorders, 
• secondary (symptomatic) headache disorders, and 
• OFP disorders including cranial neuralgias. 

Chronic headache or OFP is defined as headache or OFP that occurs on at least 50% of the days during at least 3 months and lasting at least 2 hours per day.

Only chronic secondary headache and chronic secondary OFP disorders are included here; chronic primary headache or OFP disorders are listed under chronic primary pain syndromes that have been described in a companion publication.

The subdivisions of chronic secondary OFP of ICHD-3 are complemented by the Diagnostic Criteria for Temporomandibular Disorders and contributions from the International Association for the Study of Pain Special Interest Group on Orofacial and Head Pain and include chronic dental pain.

The ICD-11 codes described here are intended to be used in combination with codes for the underlying diseases, to identify patients who require specialized pain management. In addition, these codes shall enhance visibility of these disorders in morbidity statistics and motivate research into their mechanisms.

The IASP classification of chronic pain for ICD-11: chronic secondary visceral pain. – PubMed – NCBI

Chronic visceral pain is a frequent and disabling condition. Despite high prevalence and impact, chronic visceral pain is not represented in ICD-10 in a systematic manner.

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 

• by persistent inflammation,
• by vascular mechanisms or 
• by mechanical factors. 

The pain intensity is not necessarily fully correlated with the disease process, and the chronic visceral pain may persist beyond successful treatment of the underlying cause. 

This article describes how a new classification of chronic secondary visceral pain is intended to facilitate the diagnostic process and to enable the collection of accurate epidemiological data. 

Furthermore, it is hoped that the new classification will improve the tailoring of patient-centered pain treatment of chronic secondary visceral pain and stimulate research. 

Chronic secondary visceral pain should be distinguished from chronic primary visceral pain states that are considered diseases in their own right.

The IASP classification of chronic pain for ICD-11: chronic secondary musculoskeletal pain. – PubMed – NCBI

Chronic musculoskeletal pain is defined as chronic pain arising from musculoskeletal structures such as bones or joints.

I believe this defines the pain from EDS. With our defective connective tissue, parts of the body (bones, organs, blood vessels) can move from their correct position and this often results in pain.

EDS pain is chronic pain only in the sense that the pain occurs daily, though in different places for different reasons.

EDS pain isn’t constant unchanging pain: it pops up in new places and sometimes disappears as unpredictably as it arrives, first in an ankle, then in a hip, then on the left side of the sacrum, then on the right side.

This was extremely puzzling to me before I knew I had EDS, which finally explained my traveling pains.

Although comprising the most prevalent set of chronic pain conditions, it was not represented appropriately in the 10th edition of the International Classification of Diseases (ICD-10), which was organized mainly according to anatomical sites, was strongly focused on musculoskeletal disease or local damage, and did not consider the underlying mechanisms of pain.

The new ICD-11 classification introduces the concept of chronic primary and secondary musculoskeletal pain, and integrates the biomedical axis with the psychological and social axes that comprise the complex experience of chronic musculoskeletal pain.

Chronic primary musculoskeletal pain is a condition in its own right, not better accounted for by a specific classified disease.

Chronic secondary musculoskeletal pain is a symptom that arises from an underlying disease classified elsewhere.

Such secondary musculoskeletal pain originates in persistent nociception in musculoskeletal structures from local or systemic etiologies, or it may be related to deep somatic lesions.

It can be caused

• by inflammation,
• by structural changes, or
• by biomechanical consequences of diseases of the nervous system.

It is intended that this new classification will facilitate access to patient-centered multimodal pain management and promote research through more accurate epidemiological analyses.

The IASP classification of chronic pain for ICD-11: applicability in primary care. – PubMed – NCBI

The International Classification of Diseases, 11th Revision (ICD-11), proposes, for the first time, a coding system for chronic pain. 

This system contains 

• 1 code for “chronic primary pain,” where chronic pain is the disease, and 
• 6 codes for chronic secondary pain syndromes, where pain developed in the context of another disease. 

This provides the opportunity for routine, standardised coding of chronic pain throughout all health care systems.

In primary care, this will confer many important, novel advantages over current or absent coding systems. Chronic pain will be recognized as a centrally important condition in primary care. 

The capacity to measure incidence, prevalence, and impact will help in identification of human, financial, and educational needs required to address chronic pain in primary care. Finally, opportunities to match evidence-based treatment pathways to distinct chronic pain subtypes will be enhanced.

The IASP classification of chronic pain for ICD-11: functioning properties of chronic pain. – PubMed – NCBI

Physical, mental, and social well-being are part of the concept of health according to the World Health Organization, in addition to the absence of disease and infirmity.

Therefore, for a full description of a person’s health status, the International Classification of Functioning, Disability and Health (ICF) was launched in 2001 to complement the existing International Classification of Diseases (ICD).

The 11th version of the ICD (ICD-11) is based on so-called content models, which have 13 main parameters. 

One of them is functioning properties (FPs) that, according to the WHO, consist of the activities and participation components of the ICF.

Recently, chronic pain codes were added to the 11th edition of the ICD, and hence, a specific set of FPs for chronic pain is required as a link to the ICF. In addition, pain is one of the 7 dimensions of the generic set of the ICF, which applies to any person.

#So just as we remove pain as a factor for patient satisfaction, the international community adds it to the criteria for Classification of Functioning, Disability and Health (ICF)

This article describes the current consensus proposal by the International Association for the Study of Pain (IASP) and the International Society of Physical and Rehabilitation Medicine (ISPRM) for a specific set of FPs of chronic pain, which will have to be empirically validated in a next step. 

The combined use of ICD-11 and ICF is expected to improve research reports on chronic pain by a more precise and accurate description of each diagnostic category.