Summary The Taxonomy Subcommittee recommended the current International Association for the Study of Pain (IASP) definition of pain as "An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage . " IASP Council in 1979 . This definition has been widely accepted by health professionals and researchers in the field of pain and adopted by several professional, governmental and non-governmental organizations, including the World Health Organization. In recent years, some in the field have reasoned that advances in our understanding of pain warrant a reevaluation of the definition and have proposed modifications. Therefore, in 2018, the IASP formed a 14-member multinational Presidential Task Force, comprising individuals with extensive experience in clinical and basic pain-related sciences, to evaluate the current definition and accompanying note and recommend whether they should be retain or change. This review provides a synopsis of the critical concepts, analysis of IASP member and public comments, and the committee’s final recommendations for revisions to the definition and notes, which were discussed over a 2-year period. Ultimately, the task force recommended that the definition of pain be revised to "An unpleasant sensory and emotional experience associated with, or similar to that associated with, actual or potential tissue damage ," and that the accompanying notes be updated to a Bulleted list including etymology. The revised definition and notes were unanimously accepted by the IASP Council earlier this year. |
“Scientific and medical definitions are tools. Even when we recognize them as imperfect or provisional, awaiting replacement by an improved version, they perform work that cannot be achieved with less precise instruments." David B. Morris
In 1978, after 2 years of deliberations, the Taxonomy Subcommittee of the International Association for the Study of Pain (IASP), chaired by Professor Harold Merskey and including representatives from various specialties, recommended definitions of "Pain Terms" to the Council. from IASP. The subcommittee’s recommendations, which were strongly supported by then-IASP President John J. Bonica and approved by the Council more than 4 decades ago , included the current IASP definition of pain.
Pain was defined as: “An unpleasant sensory and emotional experience associated with actual experience or potential tissue damage, or described in terms of such damage” (Table 1). The subcommittee report noted that definitions may be modified as new knowledge is acquired and that the recommendations were intended to "serve as an operational framework, not as a constraint on future development ."
The IASP definition of pain has been globally accepted by healthcare professionals and researchers in the field of pain, and has been adopted by various professional, governmental and
non-governmental organizations, including the WHO. Although there have been subsequent revisions and updates to the list of associated pain terms (1986, 1994, 2011), the IASP definition of pain itself has remained unchanged .
However, in recent years, some in the field have argued that advances in our understanding of pain in its broadest sense warrant a reevaluation of the definition. Several proposed modifications to the current definition of pain have stimulated considerable discussion. with strong, sometimes fervent, opinions that favor or oppose the need for revision.
Recognizing these ongoing discussions, IASP President Judith Turner formed a Presidential Task Force in spring 2018 to “evaluate the current IASP definition of pain and accompanying note” and recommend whether they “should be retained or changed in based on current evidence" knowledge-based". A 14-member working group was formed composed of people from several nations who had extensive experience in clinical and basic sciences related to pain. The working group deliberated over a period of almost 2 years (2018-2020).
This review provides a synopsis of working group members’ discussions of critical concepts, analysis of comments from IASP members and the public, and the committee’s final recommendations for revisions to the definition and notes that were unanimously accepted by the IASP Council early this year.
Arguments for and against updating the IASP definition
Pain can vary widely in intensity, quality and duration and has diverse mechanisms and pathophysiological meanings. Therefore, defining the concept of pain concisely and precisely presents a challenge. Several prominent leaders in the last century have alluded to this problem, including Sir Thomas Lewis, who wrote in the preface to his monograph entitled PAIN, "Reflection tells me that I am so far from being able to define pain that the attempt could not serve as a nothing".
Merskey, chair of the IASP Taxonomy Subcommittee, recognized that pain was “a psychological concept and not a physical measure and that the experience of pain had to be distinguished from noxious stimulation .” The current IASP definition (1979) recognizes that although Tissue injury is a common antecedent of pain; pain may be present even when tissue damage is not perceptible.
The strengths of this definition include its recognition of the multidimensional aspects of pain, its brevity, and its simplicity. The definition has helped provide a common understanding of the term pain to clinicians, researchers, and people with pain around the world and has influenced health policy, research, and clinical care.
Text box 1. IASP definition of pain (1979) Pain : An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Note Pain is always subjective . Each individual learns the application of the word through early life injury-related experiences. Biologists recognize that stimuli that cause pain can damage tissue. Consequently, pain is that experience that we associate with actual or potential tissue damage. It is undoubtedly a sensation in a part or parts of the body, but it is also always unpleasant and therefore also an emotional experience . Experiences that resemble pain, for example, pins and needles, but are not unpleasant, should not be called pain. Abnormal unpleasant experiences (dysesthesias) can also be painful but not necessarily because, subjectively, they may not have the usual sensory qualities of pain. Many people report pain in the absence of tissue damage or any probable pathophysiological cause; Usually this happens for psychological reasons . There is no way to distinguish your experience from one due to tissue damage if we take the subjective report. If they consider their experience to be pain and report it in the same way as pain caused by tissue damage, it should be accepted as pain. This definition avoids linking pain to the stimulus. The activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain, which is always a psychological state , although we can well appreciate that pain most often has a proximate physical cause. |
| Revised IASP Definition of Pain (2020). An unpleasant sensory and emotional experience associated or similar to that associated with actual or potential tissue damage. Grades
Etymology Middle English, from Anglo-French comb (pain, suffering), from Latin poena (penalty, punishment), in turn from Greek poin e (payment, penalty, reward). < * The Montreal Declaration, a document developed during the First International Pain Summit on September 3, 2010, states that "Access to pain treatment is a fundamental human right." |
Criticisms of the definition
Criticisms of the IASP definition have included that it is "Cartesian" , ignoring the multiplicity of mind-body interactions, and that it neglects "the ethical dimensions of pain" and does not adequately address pain in underserved populations such as newborns and the elderly. .
It has been argued that the current definition emphasizes verbal self-report at the expense of non-verbal behaviors that can provide vital information, especially in animals and non-human humans with impaired cognition or language skills.
A concern recently expressed about the current definition was that it excluded the cognitive and social factors that are integral to the experience of pain. Furthermore, the term "nasty" has been discussed as potentially trivializing the severe pain and suffering associated with many acute and acute illnesses. Chronic clinical pain states and does not capture "the full range of words that could be used to describe the experience and its associated suffering ."
Finally, it has also been argued that pain is more than a symptom; chronic pain can be a disease with its own clinical course, and therefore the definition should reflect this perspective.
In recent years, several alternative definitions have been proposed. Williams and Craig defined pain as “a distressing experience associated with actual or potential tissue damage with sensory, emotional, cognitive, and social components.” Cohen et al. offered the following revised definition: "Pain is a mutually recognizable somatic experience that reflects a person’s understanding of a threat to his or her bodily or existential integrity . " Wright and Ayde have proposed other definitions and modifications to the IASP definition.
The note accompanying the current definition has also been criticized as redundant (i.e., reiterating concepts already present in the definition), outdated (statements such as "pain in the absence of tissue damage or any probable pathophysiological cause" generally have "reasons" psychological), and lack of precision .
Concepts, discussions and initial recommendations
During early discussions among members of the working group, consensus was achieved regarding certain basic premises. The definition should be valid for acute and chronic pain and apply to all pain conditions, regardless of their pathophysiology (e.g., nociceptive, neuropathic, and nociplastic).
Second, the definition of pain should be applicable to humans and non-human animals . Third, pain needed to be defined whenever possible from the perspective of the experiencer , rather than an outside observer.
The goal was to develop a clear, concise, and unambiguous statement that describes the varied experiences of pain, while recognizing their diversity and complexity.
The working group recognized from its early deliberations that the notes section would benefit from revision. The members of the working group agreed that the note was not intended to be a treatise on the biology of pain, nor the diagnostic criteria for pain, but rather should emphasize important aspects of the complexity of pain that were difficult to capture in a brief definition. .
Considerable discussion centered on whether to include the social aspects of pain in the definition. Although members of the working group appreciated the importance of the social aspects of the experience of acute and chronic pain, the majority opinion was that they deserved to be highlighted in the note, but not an essential component of the definition. One argument put forward was that the influence of social context was not unique to pain, but was shared by other sensory experiences, such as vision and hearing. Rolf-Detlef Treede asked rhetorically in his commentary: "Can a person alone on a desert island not experience pain?"
The use of the phrase "associated with" to express the relationship between the experience and tissue damage in the current definition has also been criticized as lacking clarity. The phrase “typically caused by” was considered a replacement to clarify this relationship between tissue damage and the experience of pain.
A major concern regarding the current definition related to the phrase "described in terms of such harm" . Several possible replacements for this phrase were discussed, implying a requirement for verbal communication. Alternative verbs that were considered in an effort to encompass nonverbal behaviors of humans and animals included “expressed,” “perceived,” “interpreted,” “inferred,” and “apprehended . ”
In early deliberations, most members of the working group preferred the verb "perceived" . An early definition proposed by the working group was therefore, "An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or perceived as such damage."
However, this initial preference for the phrase "perceived as such harm" as a replacement for "described in terms of such harm" was later criticized as problematic and potentially having the unintended consequence of excluding the same groups of individuals as the group. of work he was trying to include in his review (neonates, people with severe intellectual and developmental disabilities, and most non-human animals).
Based on the IASP Council’s comments on the draft definition and note in November 2018, the working group obtained additional consultations with experts in ethics and philosophy, and held additional discussions on language refinement. The working group also agreed to seek feedback from the broader community on its initial recommendation and to revise the definition and note based on the comments received.
Discussion of controversial topics where decisions were based on majority opinion
The revised definition retains from the current definition an emphasis on pain as an experience.
The note explicitly distinguishes pain as a personal experience distinct from nociception. Although the working group returned to the use of the term "unpleasant" to replace "aversive" , the new definition retains a reference to tissue injury: "...associated with, or resembling, actual or potential tissue injury." to distinguish pain from other aversive experiences (e.g., nausea, itching, and dizziness).
Several task force members agreed with a theme highlighted in public feedback that tissue injuries were given too much weight in the new definition. Although tissue injury certainly plays a role in nociceptive pain, neuropathic pain is a direct consequence of injury or disease of the somatosensory nervous system and can be felt in areas without tissue damage .
In neuropathic pain , the pain may be experienced away from the nervous system injury or disease (e.g., in the leg and foot for people with nerve root compression, or phantom pain for people who have nerve root compression). missing a limb). Likewise, tissue injury plays no proven role in nociplastic pain .
Furthermore, it has been argued that in chronic pain, the relationship between pain and tissue status is less predictable.
An illustrative example is the discordance between reports of pain and structural abnormalities visualized by imaging in patients. with knee osteoarthritis.
The IASP has defined nociplastic pain as “pain arising from impaired nociception despite no clear evidence of actual or threatened tissue damage causing activation of peripheral nociceptors or evidence of disease or injury to the somatosensory system causing the pain.” pain." It is thought that nociplastic pain may be common and play a role in many common chronic pain conditions such as fibromyalgia, low back pain, and headache.
Although many of the working group members felt that nociplastic pain is captured in the revised definition by the phrase "or resembling that caused by actual or potential tissue injury" , other working group members responded that this was inappropriate. The latter group thought that a definition that did not more specifically encompass nociplastic pain syndromes would not fully encompass the complexity of human chronic pain.
Some members also argued that it was necessary to include a role for social injuries , such as psychological trauma or abuse, in the new definition to address all clinically important forms of chronic pain.
| Revised IASP Definition of Pain (2020). Pain is an unpleasant sensory and emotional experience associated with or similar to that associated with actual or potential tissue damage. |
Potential benefits of this new definition for both research and patient care
In 2013, IASP formed a working group to produce and update a classification of pain diseases for international use. As a result of this work, the new edition of The International Classification of Diseases (ICD-11), which the World Health Organization adopted in 2019, includes a classification of chronic pain for the first time.
In the coming years, ICD-11 will be adopted in several countries. Therefore, a revised definition of pain is very timely and aligns with this and other current efforts to advance the ontological frameworks within which pain resides.
These combined IASP efforts are important steps in recognizing pain as an important health condition and will transform pain research and the care of people with pain around the world.
Final recommendations
The final recommendation of the working group that was unanimously approved by the members of the IASP Council. In accordance with the vision of the founding members of the IASP and the first IASP Subcommittee on Taxonomy, this working group hopes that the revised definition and accompanying notes will be a living document that will be updated in accordance with future progress in the field.
Image : The Broken Column, Frida Kahlo, Oil (30 x 39 cm.), Dolores Olmedo Museum, Mexico City (Mexico).
