Secondary Logo

Journal Logo

The IASP classification of chronic pain for ICD-11: chronic primary pain

Nicholas, Michaela; Vlaeyen, Johan W.S.b,c,d; Rief, Winfriede; Barke, Antoniae; Aziz, Qasimf; Benoliel, Rafaelg; Cohen, Miltonh; Evers, Stefani; Giamberardino, Maria Adelej; Goebel, Andreask; Korwisi, Beatricee; Perrot, Sergel; Svensson, Peterm,n; Wang, Shuu-Jiuno,p; Treede, Rolf-Detlefq,*; ; The IASP Taskforce for the Classification of Chronic Pain

doi: 10.1097/j.pain.0000000000001390
Narrative Review

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.

aPain Management Research Institute, Royal North Shore Hospital, University of Sydney, Sydney, Australia

bResearch Group Health Psychology, University of Leuven, Leuven, Belgium

cDepartment of Clinical Psychological Science, Maastricht University, Maastricht, The Netherlands

dTRACE, Center for Translational Health Research, KU Leuven—Ziekenhuis Oost-Limburg, Genk, Belgium

eDivision of Clinical Psychology and Psychotherapy, Department of Psychology, Philipps-University Marburg, Marburg, Germany

fCentre for Neuroscience and Trauma, Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary, University of London, London, United Kingdom

gDepartment of Diagnostic Sciences, Rutgers School of Dental Medicine, Rutgers, Newark, NJ, United States

hSt Vincent's Clinical School, UNSW Medicine, Sydney, New South Wales, Australia

iDepartment of Neurology, Krankenhaus Lindenbrunn and Faculty of Medicine, University of Münster, Münster, Germany

jDepartment of Medicine and Science of Aging, CeSI-MeT, G D'Annunzio University of Chieti, Chieti, Italy

kPain Research Institute, University Hospital Aintree, University of Liverpool, Liverpool, United Kingdom

lPain Clinic, Cochin Hospital, Paris Descartes University, INSERM U 987, Paris, France

mSection of Orofacial Pain and Jaw Function, Institute of Odontology and Oral Health, Aarhus University, Aarhus, Denmark

nDepartment of Dental Medicine, Karolinska Insitutet, Huddinge, Sweden

oThe Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan

pBrain Research Center and Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan

qDepartment of Neurophysiology, CBTM, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany

*Corresponding author. Address: Department of Neurophysiology, Centre for Biomedicine and Medical Technology Mannheim, Medical Faculty Mannheim, Heidelberg University, Ludolf-Krehl-Str.13-17, 68167 Mannheim, Germany. Tel.: +49 (0)621 383 71 400; fax: +49-(0)621 383 71 401. E-Mail address: (R.-D. Treede).

Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (

M. Nicholas, J.W.S. Vlaeyen, W. Rief, and A. Barke contributed equally to the manuscript.

Back to Top | Article Outline

1. Background on chronic primary pain

There are 2 main diagnostic classification systems used internationally for chronic pain, apart from headaches: the Diagnostic and Statistical Manual (DSM) published by the American Psychiatric Association (APA), and the International Classification of Diseases (ICD) published by the World Health Organization (WHO). However, both have been found wanting in their accounts of chronic pain conditions. In particular, neither system reflects the developments in pain research over the last 2 decades, and they do not have clear treatment or management implications.10,15,16,38,61 To illustrate, ICD-10 refers to pain attributable exclusively to an underlying pathophysiological mechanism.19 In the absence of a clear (pathophysiological) etiology, and when biological, psychological, and social factors seem to be contributing to a chronic pain presentation,15ICD-10 offers only the option of “somatoform pain disorder.” However, this classification cannot be used when pathophysiological factors are also considered to be contributing to the pain problem.39

These distinctions have important treatment implications. As Taylor and colleagues pointed out, if we accept that chronic pain is a disease or a long-term condition, “then the philosophy of care may change from a biomedical model that views chronic pain as a symptom to that of a biopsychosocial one that views chronic pain as a disease or long-term condition” (p. 1948).53 In an attempt to address the problems with the representation of chronic pain in ICD, the German adaptation of ICD-10 (ICD-10-GM) introduced the concept of “chronic pain disorder with somatic and psychological factors.”18 It was an important step to acknowledge equal contributions of somatic and psychological factors, and the concept seems well-accepted. However, not only is this diagnosis limited to German-language countries, it still rests in the psychiatric section of the classification. Conceptually and clinically, it seems overly broad: it can be applied to most chronic pain conditions and fails to recognize subtypes. In this article, the suggested concept of chronic primary pain (CPP) overcomes these limitations by providing a clear definition unencumbered by inappropriate classification within psychiatric disorders, and it allows for subtypes. The challenge to conceptualize chronic pain as a long-term condition has been accentuated by advances in the understanding of psychological, social, and central nervous system mechanisms that may account for many hitherto inexplicable pain phenomena.37,51,60,61 These developments have meant that attempts to classify chronic pain presentations need to acknowledge the likelihood of multiple interacting contributors to a chronic pain presentation. The alternative of pain being either “somatic” or “psychogenic” has become obsolete in several ways. Psychological factors such as learning and coping play a role in chronic pain that was previously considered “somatic,” eg, chronic osteoarthritis (now classified as one of the “chronic secondary pain syndromes”). Vice versa, biological changes are closely linked to psychological processes; this is most obvious in neurophysiological brain reactions contributing to changes in pain perception. As will become apparent, these developments are acknowledged by the new diagnostic entity of CPP. The new entity will also provide a framework to unite conditions that have hitherto been scattered throughout the ICD and help to focus on their commonalities and differences.

Back to Top | Article Outline

2. The need for a classification

To overcome the shortcomings identified in previous and current versions of both DSM and ICD, this article proposes for ICD-11 the new diagnosis of CPP, which would be appropriate independently of identified biological or psychological contributors unless another diagnosis would better account for the presenting symptoms. The goal was to create a classification that will be useful in both primary care and in specialized pain management settings. It is also proposed that, as much as possible, the classification of pain conditions should be cast in “positive” terms, using “observable” concepts, and that diagnosis “by exclusion” should be avoided.56

Back to Top | Article Outline

3. The IASP task force ICD initiative

To remedy the lack of accurate classification of chronic pain in general and chronic pain where disease-oriented pain diagnoses are not appropriate, the International Association for the Study of Pain (IASP) established a Task Force that worked in close co-operation with WHO representatives in generating a systematic and improved classification of chronic pain.56 The classification is dedicated exclusively to chronic pain syndromes and excludes acute pain. The Task Force subchapter on CPP was steered by the first 2 authors.

Chronic pain was defined as pain23 that lasts or recurs for longer than 3 months.55 This definition was chosen because it provides a clear operationalization that is in line with widely used criteria in other fields of medicine. A code for the severity of the chronic pain syndrome was added, which records the intensity of the pain, the emotional distress, and the interference in daily activities due to pain. To assist with the specification of the severity of the pain, the use of numerical rating scales categorizing its 3 dimensions is recommended.55 Each dimension can be rated on a 0 to 10 scale (where 0 = nil and 10 = extreme), which can then be categorized to yield a code (0-3) for each dimension (where 0 = absent; 1-3/10 = 1 or mild; 4-6/10 = 2 or moderate; and 7-10/10 = 3 or severe). This will allow a case to be given a code of 0 to 3 for each dimension. The use of these codes is illustrated in the case vignettes 1-5 accompanying the text. ICD-11 will be coordinated with the International Classification of Functioning, Disability and Health (ICF) that will provide additional features of activities and participation.32

The classification presented here is integrated with the “frozen version” of ICD-11, published by WHO on June 18, 2018. A previous version had undergone field testing by WHO for line coding and case coding in 2017, through the IASP website.

Back to Top | Article Outline

4. Classification of chronic primary pain

Many chronic pain conditions have an obscure etiology and pathophysiology, but they are characterized by a complex interplay of biological, psychological, and social factors.15 Currently, these conditions are covered by labels such as chronic widespread pain (CWP), fibromyalgia, complex regional pain syndrome, type I (CRPS1), temporomandibular disorder (TMD), irritable bowel syndrome (IBS), and most back pain and neck pain conditions, which invariably include vague and ambiguous terms such as “nonspecific,” “somatoform,” or “functional.” The term “chronic primary pain” was chosen after extensive consultation with the ICD-11 revision committee and is expected to have widespread acceptability, especially from a nonspecialist perspective.

The definition of the new diagnosis of CPP is intended to be agnostic with regard to etiology; in particular, it aims to avoid the obsolete dichotomy of “physical” vs “psychological,”28 as well as exclusionary terms that define something by what is absent, such as “nonspecific.” The meaning of “functional” is also ambiguous. Some take it to mean “all in the mind” and others as a “disorder of function.”54

The introduction of “chronic primary pain” eliminates this ambiguity. Chronic primary pain is defined as pain in one or more anatomical regions that

  • (1) persists or recurs for longer than 3 months
  • (2) is associated with significant emotional distress (eg, anxiety, anger, frustration, or depressed mood) and/or significant functional disability (interference in activities of daily life and participation in social roles),
  • (3) and the symptoms are not better accounted for by another diagnosis.

In other words, the experience of chronic pain should be sufficiently concerning for the person to seek help for it. As in all conditions, before a diagnosis is made, it has to be ascertained whether another diagnosis better accounts for the chronic pain presentation, in which case, the diagnoses are the chronic “secondary” pain syndromes described in the companion articles: chronic cancer pain,4 chronic postsurgical or posttraumatic pain,45 chronic neuropathic pain,44 chronic secondary headache or orofacial pain,5 chronic secondary visceral pain,2 and chronic secondary musculoskeletal pain.35

Back to Top | Article Outline

4.1. The general structure of the classification of chronic primary pain

Chronic primary pain can occur in any body system (eg, nervous, musculoskeletal, and gastrointestinal systems), and in any body site (face, low-back, neck, upper-limb, thorax, abdominal, pelvis, and urogenital region), or in a combination of body sites (eg, widespread pain). This is mirrored by the general structure of the classification. Subtypes of CPP are listed in Figure 1. A complete overview of all CPP conditions as implemented in the ICD-11 foundation layer is provided in the supplementary material accompanying this article (available at

Figure 1.

Figure 1.

In the “frozen linearization” of ICD-11, CPP receives the diagnostic code MG30.0. If, however, the subtype remains unclear, the code “chronic primary pain unspecified” (MG30.0Z) will be appropriate. We expect that the subtypes are more informative and will often be identified easily.

Back to Top | Article Outline

4.2. The diagnostic codes in the classification of chronic primary pain

All codes share the characteristics of CPP explained above. Specifically, it is chronic pain in one or more anatomical regions that persists or recurs for longer than 3 months and is associated with significant emotional distress and/or significant functional disability. The emotional distress can take many forms, such as demoralization, depressed mood, anxiety, anger, or frustration. Functional disability also covers a wide range of interference in daily life, such as difficulties working, sleeping, or taking part in social activities. In addition to these common features, the individual types of CPP have unique characteristics that distinguish one particular diagnosis from another.

Back to Top | Article Outline

4.2.1. Chronic widespread pain

Chronic widespread pain is diffuse musculoskeletal pain in at least 4 of 5 body regions and in at least 3 or more body quadrants (as defined by upper–lower/left–right side of the body) and axial skeleton (neck, back, chest, and abdomen).9 Chronic widespread pain is characterized by the core features of CPP, such as pain persisting for at least 3 months, and associated with significant emotional distress and/or functional disability. The diagnosis is appropriate if the pain is not directly attributable to a nociceptive process in these regions, and if there are features consistent with nociplastic pain,26 such as spontaneous or evoked pain in the affected regions, accompanied by allodynia and/or hyperalgesia and identified psychological and social contributors. Chronic widespread pain is often associated with increased medical comorbidity, including sleep disturbances, obesity, hypertension, and diabetes.31

Back to Top | Article Outline Fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a form of CWP, which is defined as pain in at least 4 of 5 body regions (in at least 3 or 4 body quadrants), and is associated with sleep disorders, cognitive dysfunction, and somatic symptoms. The symptoms have been present at a similar level for at least 3 months and are not better accounted for by another diagnosis. Definitions of FMS have been repeatedly revised since it was first recognized as a rheumatic disease by WHO in 1992. Some authorities prefer to reserve the term FMS for the more severe presentations of the spectrum encompassed in CWP/FMS, but this approach reflects a quantitative rather than a qualitative distinction that depends on criteria that have yet to be validated.20,42Case vignette 1 features a patient with FMS.

Back to Top | Article Outline

4.2.2. Complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a type of CPP characterized by pain in a regional distribution that usually starts distally in an extremity after trauma and that is disproportionate in magnitude or duration to the typical course (of pain) after similar tissue trauma.6,8 The pain is spontaneous but can typically also be evoked. Complex regional pain syndrome is further characterized by signs indicating autonomic and inflammatory changes in the affected body region that may vary between patients and over time.6 Patients can present with hyperalgesia, allodynia, skin color and temperature changes, sweating, edema, altered hair and nail growth, dystrophic skin, reduced strength, tremors and dystonia in the affected limb, and focal osteoporosis.21 Some of these changes may be related to nociplastic mechanisms,26 and they may change over time. At a late stage, some patients present with muscle atrophy, and joint and tendon retraction (see case vignette 2). Two subtypes of CRPS have been delineated: type 1 and type 2. Both can occur after trauma, but in CRPS type 1, there is no peripheral nerve injury, while evidence of peripheral nerve injury is required for CRPS type 2.49 Although neuropathic mechanisms are commonly believed to be associated with CRPS type 2,45 and nociplastic mechanisms are believed to be associated with CRPS type 1,26 recent studies have cast doubt on the degree of difference between the 2 types of CRPS once established.33 The definition of CRPS is also part of the ICD-11 chapter on disorders of the autonomic nervous system and cross-linked to CPP.

Back to Top | Article Outline

4.2.3. Chronic primary headache or orofacial pain

Chronic primary headache or orofacial pain is defined as headache or orofacial pain that occurs on at least 15 days per month for longer than 3 months. The duration of pain per day is at least 2 hours5 (untreated), or several shorter attacks per day may occur.34,43 Other chronic headache or orofacial pain diagnoses to be considered are listed under chronic secondary headache or orofacial pain. For most purposes, patients receive a diagnosis according to the phenotypes of headache or orofacial pain with which they currently present or with which they have presented within the last year. Each distinct type, subtype or subform of headache or orofacial pain within one patient must be separately diagnosed and coded. When a patient receives more than one diagnosis, these should be listed in the order of importance to the patient.17,22,46 There are several subtypes of chronic primary headache or orofacial pain.

Back to Top | Article Outline Chronic migraine

Chronic migraine is defined as headache occurring on 15 or more days/month for more than 3 months, which, on at least 8 days/month, has the features of migraine headache. Migraine is a recurrent headache disorder manifesting in attacks lasting 4 to 72 hours. Typical characteristics of the headache are unilateral location, pulsating quality, moderate or severe intensity, aggravation by routine physical activity, and an association with nausea and/or photophobia and phonophobia.17,22,46

Back to Top | Article Outline Chronic tension-type headache

Chronic tension-type headache is a frequent episodic headache, which occurs for at least 2 hours per day on 15 or more days per month for more than 3 months. Typically, they are bilateral, pressing, or tightening in quality and of mild to moderate intensity, lasting hours to days, but can be unremitting. The pain does not worsen with routine physical activity but may be associated with mild nausea, photophobia, or phonophobia.17,22,46

Back to Top | Article Outline Trigeminal autonomic cephalalgias

Trigeminal autonomic cephalalgias (TACs) share the clinical features of unilateral headache and, usually, prominent cranial parasympathetic autonomic features (eg, lacrimation, rhinorrhoea, nasal congestion, and eyelid oedema), which are ipsilateral to the headache. Diagnostic labels commonly used for TACs include cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks, and hemicrania continua. These are considered chronic TACs if the TAC attacks persist for 1 year or longer without remission, or with remission periods lasting less than 3 months.17,22,46

Back to Top | Article Outline Chronic temporomandibular disorder

Chronic TMD pain is one of the most common chronic facial pain syndromes and includes pain affecting the temporomandibular joints (TMJ) and masticatory muscles and associated tissues. Temporomandibular disorder is defined as chronic orofacial pain that occurs for at least 2 hours per day on at least 50% of the days over at least 3 months. There are at least 2 distinct phenotypes: pain in the masticatory muscles termed myofascial TMD pain, and pain in the TMJ or associated tissues termed TMJ arthralgia (see case vignette 3). There are also forms of chronic secondary TMD.5

Back to Top | Article Outline Chronic burning mouth pain

Chronic burning mouth pain is chronic orofacial pain characterized by intraoral burning or dysesthetic sensation that recurs for more than 2 hours per day on 50% of the days over more than 3 months, without evident causative lesions on clinical investigation and examination. Chronic primary burning mouth pain should be distinguished from secondary burning mouth syndrome attributed to diagnoses such as candidiasis or vitamin B12 deficiency. Two separate phenotypes have been described: with and without somatosensory disturbances.17,22,46

Back to Top | Article Outline Chronic primary orofacial pain

Chronic primary orofacial pain is chronic pain in the mouth and face area that is associated with significant emotional distress and/or functional disability that is not better accounted for by other diagnoses of chronic primary or chronic secondary orofacial pain.5

Back to Top | Article Outline

4.2.4. Chronic primary visceral pain

Chronic primary visceral pain is CPP localized in the head or neck, thoracic, abdominal, or pelvic region. Of note, it represents one of the major categories of internal medicine. The respective anatomical location is compatible with typical referral pain patterns from specific internal organs. Chronic primary visceral pain includes pain in the head/neck viscera of the digestive system; in the thoracic region (eg, noncardiac chest pain and reflux hypersensitivity); in the abdominal region arising from viscera of the digestive system (eg, epigastric pain syndrome, IBS, centrally mediated abdominal pain syndrome, and biliary dyskinesia) and in the pelvic region due to involvement of the viscera of the digestive, urinary, and genital systems (eg, bladder pain syndrome, anal spasm, chronic pelvic pain, and chronic testicular pain).3,13,24,25,27,50,58 Several diagnoses that before this new classification were termed “functional” are to be subsumed under chronic primary visceral pain and have been renamed.54 There are several subtypes of chronic primary visceral pain. These are described next.

Back to Top | Article Outline Chronic primary chest pain syndrome

Chronic primary chest pain syndrome is recurrent primary retrosternal pain. Its anatomical location is compatible with typical referral pain patterns from esophageal origin. The pain must be present for 3 months with a symptom onset at least 6 months before the diagnosis with a frequency of at least once a week. Other esophageal symptoms such as heartburn and dysphagia must be absent. The symptoms are not better accounted for by reflux disease, other mucosal (eg, eosinophilia esophagitis) or motor processes (eg, achalasia, Jack Hammer esophagus, and diffuse esophageal spasm), cardiac causes, heartburn, dysphagia, or a diagnosis of chronic secondary visceral pain.1 The pain is perceived in the somatic tissues of the chest wall (skin, subcutis, and muscle) in areas that receive the same sensory innervation as the esophagus (referred visceral pain) and can sometimes radiate to the arm and jaw much like angina. In these areas, secondary hyperalgesia (increased sensitivity to noxious stimuli in areas other than the primary site of the nociceptive input) may occur (see case vignette 4 for an illustration of the diagnosis).41,59 The term “noncardiac” chest pain has been used to explain the symptoms,14 but this is inappropriate as it is describing the pain by an absence.

Back to Top | Article Outline Chronic primary epigastric pain syndrome

Chronic primary epigastric pain syndrome is CPP localized in the epigastric region. The distinct anatomical location is compatible with typical referral pain patterns from specific internal organs. Consistent with the ROME IV criteria, it is characterized by epigastric pain or burning that does not occur exclusively after meals, but can occur even during fasting, or even be improved after a meal. It may overlap with postprandial distress syndrome, which is associated with meal-induced dyspeptic symptoms.48 Bothersome epigastric pain and/or burning that is severe enough to impact on usual activities must be present for at least 1 day per week over the last 3 months with symptom onset at least 6 months before diagnosis. The pain may be perceived in the somatic tissues of the abdominal wall (skin, subcutis, and muscle) in areas that receive the same sensory innervation as the small or large bowel (referred visceral pain). As with other CPP diagnoses, the diagnosis of chronic primary epigastric pain syndrome should be used unless another diagnosis would better account for the presenting symptoms and findings from investigations such as upper gastrointestinal endoscopy.11,48 Postprandial epigastric bloating, belching, and nausea can also be present, but pain from biliary causes should be excluded. Presence of persistent vomiting should prompt the search for another disorder. Other digestive symptoms such as from gastroesophageal reflux disease and IBS may coexist with chronic primary epigastric pain.

Back to Top | Article Outline Irritable bowel syndrome

Irritable bowel syndrome is one of the most frequent chronic primary abdominal pain conditions. Irritable bowel syndrome is a bowel disorder in which recurrent abdominal pain occurs on average for at least 1 day/week in the last 3 months and is associated with 2 or more of the following: (1) related to defecation; (2) associated with change in frequency of stool; and (3) associated with a change in form (appearance) of stool. Criteria should be fulfilled for the last 3 months with symptom onset 6 months before diagnosis. Irritable bowel syndrome subtypes may include IBS with predominant constipation or diarrhea; IBS with mixed bowel habits; and IBS unspecified.29

Back to Top | Article Outline Chronic primary abdominal pain syndrome

Chronic primary abdominal pain is CPP localized in the abdominal region and associated with significant emotional distress and/or functional disability. The pain is usually continuous with no or only occasional associations with physiological events (eg, eating, defecation, or menses). Its anatomical location is compatible with typical referral pain patterns from specific internal organs, but the symptoms are not better accounted for by a diagnosis of chronic secondary abdominal pain. Chronic primary abdominal pain disorders may be associated with pathologies that have arisen secondary to changes in the control mechanisms of an organ or system and may be associated with neurobiological, physiological, and sometimes anatomical changes in the central nervous system.2,7,11,30,48

Back to Top | Article Outline Chronic primary bladder pain syndrome

Chronic primary bladder pain syndrome is CPP perceived in the region of the urinary bladder that is also associated with at least one other symptom, such as worsening of the pain upon bladder filling and urinary frequency during day time and/or night time. The symptoms are not better accounted for by infection or any diagnosis of chronic secondary visceral pain. The presence of sexual dysfunction or dysfunction of the lower urinary tract should be considered.2,12 Specific types of inflammation may be present in subsets of patients and need to be excluded. Other terms previously used include “interstitial cystitis,” “painful bladder syndrome,” and “PBS/IC” or “BPS/IC,” but these are no longer recommended.2,12

Back to Top | Article Outline Chronic primary pelvic pain syndrome

Chronic primary pelvic pain syndrome is CPP localized in the pelvic region. The anatomical location is compatible with typical referral pain patterns from specific internal organs of the pelvic area. The symptoms are not better accounted for by one of the other possible chronic secondary visceral pelvic pain diagnoses: chronic visceral pelvic pain from persistent inflammation, chronic visceral pelvic pain from vascular mechanisms, and chronic visceral pelvic pain from mechanical factors. Chronic primary pelvic pain includes pain in the pelvic region of the digestive and urogenital systems.3,24,36,50,58

Back to Top | Article Outline

4.2.5. Chronic primary musculoskeletal pain (other than orofacial).

Chronic primary musculoskeletal pain is CPP located in the muscles, bones, joints, or tendons. A typical example is chronic primary low-back pain (see case vignette 5). Chronic primary musculoskeletal pain syndromes are distinguished according to location: upper (chronic primary cervical pain), middle (chronic primary thoracic pain), lower back (chronic primary low-back pain), and limbs (chronic primary limb pain). Patients may present with spontaneous or evoked pain in the affected region, accompanied by allodynia and/or hyperalgesia. Here, the conditions that were formerly named “nonspecific” musculoskeletal pain are classified.

Back to Top | Article Outline

5. Discussion

Chronic primary pain is a new diagnosis in the ICD-11 classification for chronic pain that is intended to embrace a number of poorly understood conditions while avoiding obscure and potentially laden terms such as “somatoform,” “nonspecific,” or “functional.” Chronic primary pain syndromes can be conceived as health conditions in their own right, whereas in the other 6 groups of chronic pain conditions (chronic secondary pain syndromes), pain may be considered a symptom of some other underlying diseases.55 The distinction between “primary” and “secondary” has been transferred from the International Headache Classification.22 It avoids designating the basis of the pain as “psychological” or “organic” because chronic pain necessarily includes psychological and social dimensions in addition to the biological components.60

Recently, in addition to nociceptive and neuropathic mechanisms, the concept of “nociplastic” was introduced as a third neurophysiological mechanism underpinning some chronic pain conditions.26 It has been suggested that it may be particularly applicable to CPP. However, at this stage, the relationship of nociplastic pain mechanisms and chronic primary or secondary pain syndromes cannot be determined. Further development of the application of this new descriptor is in progress. However, it should be noted that it does require clinical and psychophysical findings suggestive of altered nociceptive function, and that it does not apply to patients reporting pain without hypersensitivity.

Like the other diagnoses proposed for ICD-11, CPP can be combined with optional specifiers, such as the presence of psychological and social factors and pain severity (combined ratings for pain intensity, distress, and disability). The severity ratings can be coded, and it is hoped that their dimensional nature will facilitate not only clinical communication but also interpretation of research findings. By means of these specifiers, clinicians and researchers will be able to determine whether their samples are similar to those participating in other studies that use these codes. For example, instead of describing a sample of patients as having low-back pain, researchers using ICD-11 will also be able to distinguish levels of severity (mild, moderate, and severe) that help guide treatment (or no treatment). These codes also provide clinicians in both primary care and more specialized facilities with a simple means for evaluating changes over time in their chronic pain patients.47

Naturally, the new classification of chronic pain will have to be shown to be reliable and clinically useful. The next step in the development of ICD-11 will be to encourage field trials to establish the psychometric properties of these codes and their utility. A pilot field trial in 4 countries yielded CPP and chronic secondary musculoskeletal pain as the 2 most frequent diagnostic groups, which were clearly distinguishable by both pain specialists and primary care physicians. Because the categories are more descriptive than former distinctions between “psychological and somatic” pain conditions, we expect that future evaluations will confirm higher retest reliability and inter-rater reliability compared with the previous approaches of classification.

The proposal in this article is that all chronic pain diagnoses should be presented in ICD-11 as a coherent category of diagnoses and not be divided up artificially as is the case in ICD-10. This confers a number of advantages, including when the categories are used for the worldwide collection of data for health statistics. For these statistics, different levels of granularity can be chosen. Chronic pain may be divided into primary vs 6 subtypes of secondary pain syndromes (level 1 in Fig. 1), or any of these top level chronic pain diagnoses is subdivided into one of their level 2 diagnoses (Fig. 1 here and in companion articles). The World Health Organization plans for member states to report their health statistic from 2022 onwards using level 1 and 2. We expect that this will be a useful level of aggregation, in that it provides a category for pain conditions that have hitherto been counted in less useful ways by being dispersed throughout the ICD. This represents chronic pain in health statistics, which influence health policies and allocation of resources for prevention, treatment, and rehabilitation as well as research.

The new ICD-11 CPP classification is also expected to enhance pain management outcomes, in that it allows for inferences about unknown aspects of an individual who has been assigned a specific pain category.40 Indeed, given a pain (sub)category, clinicians and researchers can infer likely causes of symptoms, predict most likely consequences, estimate a timeline, the most likely future developments, and optimize treatment plans for that person. In the case of CPP, in particular, the identification of physiological, psychological, and social contributors to pain is specifically encouraged, and this opens the way for multimodal interventions that can address these factors and potentially enhance treatment outcomes. The German experience with the national variant code F45.41 (chronic pain with somatic and psychological factors) suggests that few large chronic pain diagnoses are more useful to guide treatment and its funding than the numerous more specific ones scattered throughout ICD-10.39

Multimodal pain management is regarded as the most helpful treatment form for chronic pain. How many “variants” of multimodal pain management will be needed in the future is an important research issue. It applies to both primary and secondary pain syndromes. It is expected that the diagnoses of the new classification may be helpful in performing this research program by offering a more helpful grouping of the diagnoses. On the other hand, it should be recognized that any categorization may introduce an assimilation bias52,62 that may draw attention away from idiosyncratic features of the individual that may be important for an adequate personalized pain medicine. ICD-11 users should be aware of this potential bias to limit its impact.

Back to Top | Article Outline

6. Summary and conclusion

By including a distinct CPP syndrome classification within the ICD-11, it is hoped to avoid the problems associated with previous classifications of chronic pain when the etiology is unclear, but the emotional distress and functional disability associated with such pain are very evident, as the Global Burden of Disease project has reported.57 The availability of 6 classes of chronic secondary pain syndromes in the same classification will facilitate the distinction of pain as a disease or long-term condition from pain as a symptom,53 as already demonstrated in a pilot field trial. This classification has clear treatment and management implications: a multimodal approach that addresses the contributing psychological, social, and biological contributors is expected to lead to better outcomes for patients with CPP diagnoses of at least moderate severity, relative to unimodal interventions alone. In chronic secondary pain syndromes, there will be additional disease-specific treatment options to be considered as well. In addition, the representation of CPP in health statistics is expected to advance public policy and research.

Back to Top | Article Outline

Conflict of interest statement

W. Rief reports grants from IASP, during the conduct of the study; personal fees from Heel, personal fees from Berlin Chemie, outside the submitted work. A. Barke reports personal fees from IASP, during the conduct of the study. Q. Aziz reports grants and personal fees from Grunenthal, personal fees from Allergan, outside the submitted work. M.A. Giamberardino reports personal fees from IBSA Institute Biochimique, personal fees from EPITECH Group, personal fees from Helsinn Healthcare, grants from EPITECH Group, grants from Helsinn Healthcare, outside the submitted work. A. Goebel reports grants from Axsome, Pajunk, Biotest outside the submitted work. S.-J. Wang reports personal fees from Eli-Lilly, personal fees from Daiichi-Sankyo, grants and personal fees from Pfizer, Taiwan, personal fees from Eisai, personal fees from Bayer, personal fees from Boehringer Ingelheim, outside the submitted work. R.-D. Treede reports grants from Boehringer Ingelheim, Astellas, AbbVie, Bayer, personal fees from Astellas, Grünenthal, Bauerfeind, Hydra, Bayer, grants from EU, DFG, BMBF, outside the submitted work. The remaining authors have no conflict of interest to declare.

Back to Top | Article Outline


The authors gratefully acknowledge the financial support by the International Association for the Study of Pain and the excellent discussions with Dr. Robert Jakob of WHO.

Members of the Taskforce: Rolf-Detlef Treede (Chair), Winfried Rief (Co-chair), Antonia Barke, Qasim Aziz, Michael I. Bennett, Rafael Benoliel, Milton Cohen, Stefan Evers, Nanna B. Finnerup, Michael First, Maria Adele Giamberardino, Stein Kaasa, Beatrice Korwisi, Eva Kosek, Patricia Lavand'homme, Michael Nicholas, Serge Perrot, Joachim Scholz, Stephan Schug, Blair H. Smith, Peter Svensson, Johannes Vlaeyen, Shuu-Jiun Wang.

J.W.S. Vlaeyen is supported by the “Asthenes” long-term structural funding—Methusalem Grant (# METH/15/011) by the Flemish Government, Belgium.

Back to Top | Article Outline

Appendix A.

Back to Top | Article Outline

Supplemental digital content

Supplemental digital content associated with this article can be found online at SDC includes a complete reference list of the diagnoses entered into the foundation with the foundation IDs as well as the extension codes (specifier). Since the complete list is contained, the material is identical for all papers of the series.

Back to Top | Article Outline


[1]. Aziz Q, Fass R, Gyawali CP, Miwa H, Pandolfino JE, Zerbib F. Esophageal disorders. Gastroenterol 2016;150:1368–79.
[2]. Aziz Q, Giamberardino MA, Barke A, Korwisi B, Rief W, Treede RD; The IASP Taskforce for the Classification of Chronic Pain. The IASP classification of chronic pain for ICD-11: chronic secondary visceral pain. PAIN 2019;160:69–76.
[3]. Baranowski AP, Lee J, Price C, Hughes J. Pelvic pain: a pathway for care developed for both men and women by the British Pain Society. Br J Anaesth 2014;112:452–9.
[4]. Bennett MI, Kaasa S, Barke A, Korwisi B, Rief W, Treede RD; The IASP Taskforce for the Classification of Chronic Pain. The IASP classification of chronic pain for ICD-11: chronic cancer-related pain. PAIN 2019;160:38–44.
[5]. Benoliel R, Svensson P, Evers S, Wang SJ, Barke A, Korwisi B, Rief W, Treede RD. The IASP-classification of chronic pain for ICD-11: chronic secondary headache or orofacial pain. PAIN 2019;160:60–8.
[6]. Birklein F, Schlereth T. Complex regional pain syndrome-significant progress in understanding. PAIN 2015;156:S94–S103.
[7]. Brook RA, Kleinman NL, Choung RS, Melkonian AK, Smeeding JE, Talley NJ. Functional dyspepsia impacts absenteeism and direct and indirect costs. Clin Gastroenterol Hepatol 2010;8:498–503.
[8]. Bruehl S. Complex regional pain syndrome. Br Med J 2015;351:h2730.
[9]. Butler S, Landmark T, Glette M, Borchgrevink P, Woodhouse A. Chronic widespread pain-the need for a standard definition. PAIN 2016;157:541–3.
[10]. Cosci F, Fava GA. The clinical inadequacy of the DSM-5 classification of somatic symptom and related disorders: an alternative trans-diagnostic model. CNS Spectr 2016;21:310–17.
[11]. Enck P, Azpiroz F, Boeckxstaens G, Elsenbruch S, Feinle-Bisset C, Holtmann G, Lackner JM, Ronkainen J, Schemann M, Stengel A, Tack J, Zipfel S, Talley NJ. Functional dyspepsia. Nat Rev Dis Primers 2017;3:17081.
[12]. Engeler DS, Baranowski AP, Dinis-Oliveira P, Elneil S, Hughes J, Messelink EJ, van Ophoven A, Williams AC; European Association of Urology. The 2013 EAU guidelines on chronic pelvic pain: is management of chronic pelvic pain a habit, a philosophy, or a science? 10 years of development. Eur Urol 2013;64:431–9.
[13]. Farmer AD, Aziz Q. Mechanisms and management of functional abdominal pain. J R Soc Med 2014;107:347–54.
[14]. Fenster PE. Evaluation of chest pain: a cardiology perspective for gastroenterologists. Gastroenterol Clin North Am 2004;33:35–40.
[15]. Fillingim RB, Bruehl S, Dworkin RH, Dworkin SF, Loeser JD, Turk DC, Widerstrom-Noga E, Arnold L, Bennett R, Edwards RR, Freeman R, Gewandter J, Hertz S, Hochberg M, Krane E, Mantyh PW, Markman J, Neogi T, Ohrbach R, Paice JA, Porreca F, Rappaport BA, Smith SM, Smith TJ, Sullivan MD, Verne GN, Wasan AD, Wesselmann U. The ACTTION—American Pain Society Pain Taxonomy (AAPT): an evidence-based and multidimensional approach to classifying chronic pain conditions. J Pain 2014;15:241–9.
[16]. Fishbain DA. DSM-IV: implications and issues for the pain clinician. Am Pain Soc Bull 1995;5:6–18.
[17]. Forssell H, Jääskeläinen S, List T, Svensson P, Baad-Hansen L. An update on pathophysiological mechanisms related to idiopathic orofacial pain conditions with implications for management. J Oral Rehabil 2015;42:300–22.
[18]. Graubner B. ICD-10-GM 2009 Internationale statistische Klassifikation der Krankheiten und verwandter Gesundheitsprobleme, 10. Revision, German Modification. Köln: Deutscher Ärzte-Verlag, 2008.
[19]. Gustavsson A, Bjorkman J, Ljungcrantz C, Rhodin A, Rivano-Fischer M, Sjolund KF, Mannheimer C. Socio-economic burden of patients with a diagnosis related to chronic pain—register data of 840,000 Swedish patients. Eur J Pain 2012;16:289–99.
[20]. Haliloglu S, Carlioglu A, Akdeniz D, Karaaslan Y, Kosar A. Fibromyalgia in patients with other rheumatic diseases: prevalence and relationship with disease activity. Rheumatol Int 2014;34:1275–80.
[21]. Harden RN, Bruehl S, Perez RS, Birklein F, Marinus J, Maihofner C, Lubenow T, Buvanendran A, Mackey S, Graciosa J, Mogilevski M, Ramsden C, Chont M, Vatine JJ. Validation of proposed diagnostic criteria (the “Budapest Criteria”) for complex regional pain syndrome. PAIN 2010;150:268–74.
[22]. Headache Classification Committee. The international classification of headache disorders, 3rd edition. Cephalalgia 2018;38:1–211.
[23]. IASP. International Association for the Study of Pain, terminology [electronic source]. Available at: Accessed October 04, 2018.
[24]. Jarrell J, Arendt-Nielsen L. Quantitative sensory testing in gynaecology: improving preoperative and postoperative pain diagnosis. J Obstet Gynaecol Can 2013;35:531–5.
[25]. Knowles CH, Aziz Q. Basic and clinical aspects of gastrointestinal pain. PAIN 2009;141:191–209.
[26]. Kosek E, Cohen M, Baron R, Gebhart GF, Mico JA, Rice ASC, Rief W, Sluka AK. Do we need a third mechanistic descriptor for chronic pain states? PAIN 2016;157:1382–6.
[27]. Kumar AR, Katz PO. Functional esophageal disorders: a review of diagnosis and management. Expert Rev Gastroenterol Hepatol 2013;7:453–61.
[28]. La Cour P. Comparison of patients diagnosed with “complex pain” and “somatoform pain”. Scand J Pain 2017;17:49–52.
[29]. Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller R. Bowel disorders. Gastroenterol 2016;150:1393–1407.e5.
[30]. Mones J, Adan A, Segú JL, López JS, Artés M, Guerrero T. Quality of life in functional dyspepsia. Dig Dis Sci 2002;47:20–6.
[31]. Morales-Espinoza EM, Kostov B, Salami DC, Perez ZH, Rosalen AP, Molina JO, Paz LG, Momblona JM, Areu JB, Brito-Zeron P, Ramos-Casals M, Siso-Almirall A. Complexity, comorbidity, and health care costs associated with chronic widespread pain in primary care. PAIN 2016;157:818–26.
[32]. Nugraha B, Gutenbrunner C, Barke A, Karst M, Schiller J, Schäfer P, Falter S, Korwisi B, Rief W, Treede RD. The IASP classification of chronic pain for ICD-11: functioning properties of chronic pain. PAIN 2019;160:88–94.
[33]. Ott S, Maihöfner C. Signs and symptoms in 1,043 patients with complex regional pain syndrome. J Pain 2018;19:599–611.
[34]. Peck CC, Goulet JP, Lobbezoo F, Schiffman EL, Alstergren P, Anderson GC, de Leeuw R, Jensen R, Michelotti A, Ohrbach R, Petersson A, List T. Expanding the taxonomy of the diagnostic criteria for temporomandibular disorders. J Oral Rehabil 2014;41:2–23.
[35]. Perrot S, Cohen M, Barke A, Korwisi B, Rief W, Treede RD; The IASP Taskforce for the Classification of Chronic Pain. The IASP classification of chronic pain for ICD-11: chronic secondary musculoskeletal pain. PAIN 2019;160:77–82.
[36]. Potts JM. Male pelvic pain: beyond urology and chronic prostatitis. Curr Rheumatol Rev 2016;12:27–39.
[37]. Rief W, Isaac M. Are somatoform disorders “mental disorders”? A contribution to the current debate. Curr Opin Psychiatry 2007;20:143–6.
[38]. Rief W, Kaasa S, Jensen R, Perrot S, Vlaeyen JWS, Treede RD, Vissers KCP. New proposals for the International Classification of Diseases-11 revision of pain diagnoses. J Pain 2012;13:305–16.
[39]. Rief W, Zenz M, Schweiger U, Rüddel H, Henningsen P, Nilges P. Redefining (somatoform) pain disorder in ICD-10: a compromise of different interest groups in Germany. Curr Opin Psychiatry 2008;21:178–81.
[40]. Rosch E. Principles of categorization. In: Margolis E, Laurence S, editors. Concepts: core readings. Cambridge: MIT Press, 1999. p. 189–206.
[41]. Sarkar S, Aziz Q, Woolf CJ, Hobson AR, Thompson DG. Contribution of central sensitisation to the development of non-cardiac chest pain. Lancet 2000;356:1154–9.
[42]. Schaefer C, Mann R, Masters ET, Cappelleri JC, Daniel SR, Zlateva G, McElroy HJ, Chandran AB, Adams EH, Assaf AR, McNett M, Mease P, Silverman S, Staud R. The comparative burden of chronic widespread pain and fibromyalgia in the United States. Pain Pract 2016;16:565–79.
[43]. Schiffman E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, List T, Svensson P, Gonzalez Y, Lobbezoo F, Michelotti A, Brooks SL, Ceusters W, Drangsholt M, Ettlin D, Gaul C, Goldberg LJ, Haythornthwaite JA, Hollender L, Jensen R, John MT, De Laat A, de Leeuw R, Maixner W, van der Meulen M, Murray GM, Nixdorf DR, Palla S, Petersson A, Pionchon P, Smith BH, Visscher CM, Zakrzewska JM, Dworkin SF; International RDC/TMD Consortium Network—International association for Dental Research, Orofacial Pain Special Interest Group—International Association for the Study of Pain. Diagnostic criteria for temporomandibular disorders (DC/TMD) for clinical and research applications: recommendations of the international RDC/TMD consortium network and the orofacial pain special interest group. J Orofac Pain 2014;28:6–27.
[44]. Scholz J, Finnerup NB, Attal N, Aziz Q, Baron R, Bennett MI, Benoliel R, Cohen M, Cruccu G, Davis KD, Evers S, First M, Giamberardino MA, Hansson P, Kaasa S, Korwisi B, Kosek E, Lavand'homme P, Nicholas M, Nurmikko T, Perrot S, Raja SN, Rice ASC, Rowbotham MC, Schug S, Simpson DM, Smith BH, Svensson P, Vlaeyen JWS, Wang SJ, Barke A, Rief W, Treede RD. The IASP classification of chronic pain for ICD-11: chronic neuropathic pain. PAIN 2019;160:53–59.
[45]. Schug SA, Lavand'homme P, Barke A, Korwisi B, Rief W, Treede RD. The IASP taskforce for the classification of chronic pain. The IASP classification of chronic pain for ICD-11: chronic postsurgical or posttraumatic pain. PAIN 2019;160:45–52.
[46]. Sharav Y, Benoliel R. Orofacial pain and headache. New York: Quintessence Publication, 2015.
[47]. Smith BH, Fors EA, Korwisi B, Barke A, Cameron P, Colvin L, Richardson C, Rief W, Treede RD. The IASP-classification of chronic pain for ICD-11: applicability in primary care. PAIN 2019;160:83–87.
[48]. Stanghellini V, Chan FK, Hasler WL, Malagelada JR, Suzuki H, Tack J, Talley NJ. Gastroduodenal disorders. Gastroenterol 2016;150:1380–92.
[49]. Stanton-Hicks M, Janig W, Hassembusch S, Haddox JD, Boas R, Wilson P. Reflex sympathetic dystrophy: changing concepts and taxonomy. PAIN 1995;63:127–33.
[50]. Stein SL. Chronic pelvic pain. Gastroenterol Clin North Am 2013;42:785–800.
[51]. Strassnig M, Stowell KR, First MB, Pincus HA. General medical and psychiatric perspectives on somatoform disorders: separated by an uncommon language. Curr Opin Psychiatry 2006;19:194–200.
[52]. Tajfel H, Wilkes AL. Classification and quantitative judgement. Br J Psychol 1963;54:101–14.
[53]. Taylor AM, Phillips K, Taylor JO, Singh JA, Conaghan PG, Choy EH, Tugwell PS, Kaiser U, Strand V, Simon LS, Mease PJ. Is chronic pain a disease in its own right? Discussions from a pre-OMERACT 2014 Workshop on chronic pain. J Rheumatol 2015;42:1947–53.
[54]. Thompson WG, Longstreth GF, Drossman DA, Heaton KW, Irvine EJ, Müller-Lissner SA. Functional bowel disorders and functional abdominal pain. Gut 1999;45(suppl 2):II43–7.
[55]. Treede RD, Rief W, Barke A, Aziz Q, Bennett MI, Benoliel R, Cohen M, Evers S, Finnerup NB, First MB, Giamberardino MA, Kaasa S, Korwisi B, Kosek E, Lavand'homme P, Nicholas M, Perrot S, Scholz J, Schug S, Smith BH, Svensson P, Vlaeyen JWS, Wang SJ. Chronic pain as a symptom and a disease: the IASP classification of chronic pain for the international classification of diseases ICD-11. PAIN 2019;160:19–27.
[56]. Treede RD, Rief W, Barke A, Aziz Q, Bennett MI, Benoliel R, Cohen M, Evers S, Finnerup NB, First MB, Giamberardino MA, Kaasa S, Kosek E, Lavand'homme P, Nicholas M, Perrot S, Scholz J, Schug S, Smith BH, Svensson P, Vlaeyen JW, Wang SJ. A classification of chronic pain for ICD-11. PAIN 2015;156:1003–7.
[57]. Vos T, Abajobir AA, Abate KH, Abbafati C, Abbas KM, Abd-Allah F, Abdulkader RS, Abdulle AM, Abebo TA, Abera SF, Aboyans V, Abu-Raddad LJ, Ackerman IN, Adamu AA, Adetokunboh O, Afarideh M, Afshin A, Agarwal SK, Aggarwal R, Agrawal A, Agrawal S, Ahmadieh H, Ahmed MB, Aichour MTE, Aichour AN, Aichour I, Aiyar S, Akinyemi RO, Akseer N, Al Lami FH, Alahdab F, Al-Aly Z, Alam K, Alam N, Alam T, Alasfoor D, Alene KA, Ali R, Alizadeh-Navaei R, Alkerwi A, Alla F, Allebeck P, Allen C, Al-Maskari F, Al-Raddadi R, Alsharif U, Alsowaidi S, Altirkawi KA, Amare AT, Amini E, Ammar W, Amoako YA, Andersen HH, Antonio CAT, Anwari P, Ärnlöv J, Artaman A, Aryal KK, Asayesh H, Asgedom SW, Assadi R, Atey TM, Atnafu NT, Atre SR, Avila-Burgos L, Avokphako EFGA, Awasthi A, Bacha U, Badawi A, Balakrishnan K, Banerjee A, Bannick MS, Barac A, Barber RM, Barker-Collo SL, Bärnighausen T, Barquera S, Barregard L, Barrero LH, Basu S, Battista B, Battle KE, Baune BT, Bazargan-Hejazi S, Beardsley J, Bedi N, Beghi E, Béjot Y, Bekele BB, Bell ML, Bennett DA, Bensenor IM, Benson J, Berhane A, Berhe DF, Bernabé E, Betsu BD, Beuran M, Beyene AS, Bhala N, Bhansali A, Bhatt S, Bhutta ZA, Biadgilign S, Bicer BK, Bienhoff K, Bikbov B, Birungi C, Biryukov S, Bisanzio D, Bizuayehu HM, Boneya DJ, Boufous S, Bourne RRA, Brazinova A, Brugha TS, Buchbinder R, Bulto LNB, Bumgarner BR, Butt ZA, Cahuana-Hurtado L, Cameron E, Car M, Carabin H, Carapetis JR, Cárdenas R, Carpenter DO, Carrero JJ, Carter A, Carvalho F, Casey DC, Caso V, Castañeda-Orjuela CA, Castle CD, Catalá-López F, Chang HY, Chang JC, Charlson FJ, Chen H, Chibalabala M, Chibueze CE, Chisumpa VH, Chitheer AA, Christopher DJ, Ciobanu LG, Cirillo M, Colombara D, Cooper C, Cortesi PA, Criqui MH, Crump JA, Dadi AF, Dalal K, Dandona L, Dandona R, das Neves J, Davitoiu DV, de Courten B, De Leo D, Defo BK, Degenhardt L, Deiparine S, Dellavalle RP, Deribe K, Des Jarlais DC, Dey S, Dharmaratne SD, Dhillon PK, Dicker D, Ding EL, Djalalinia S, Do HP, Dorsey ER, Dos Santos KPB, Douwes-Schultz D, Doyle KE, Driscoll TR, Dubey M, Duncan BB, El-Khatib ZZ, Ellerstrand J, Enayati A, Endries AY, Ermakov SP, Erskine HE, Eshrati B, Eskandarieh S, Esteghamati A, Estep K, Fanuel FBB, Farinha CSES, Faro A, Farzadfar F, Fazeli MS, Feigin VL, Fereshtehnejad SM, Fernandes JC, Ferrari AJ, Feyissa TR, Filip I, Fischer F, Fitzmaurice C, Flaxman AD, Flor LS, Foigt N, Foreman KJ, Franklin RC, Fullman N, Fürst T, Furtado JM, Futran ND, Gakidou E, Ganji M, Garcia-Basteiro AL, Gebre T, Gebrehiwot TT, Geleto A, Gemechu BL, Gesesew HA, Gething PW, Ghajar A, Gibney KB, Gill PS, Gillum RF, Ginawi IAM, Giref AZ, Gishu MD, Giussani G, Godwin WW, Gold AL, Goldberg EM, Gona PN, Goodridge A, Gopalani SV, Goto A, Goulart AC, Griswold M, Gugnani HC, Gupta R, Gupta R, Gupta T, Gupta V, Hafezi-Nejad N, Hailu GB, Hailu AD, Hamadeh RR, Hamidi S, Handal AJ, Hankey GJ, Hanson SW, Hao Y, Harb HL, Hareri HA, Haro JM, Harvey J, Hassanvand MS, Havmoeller R, Hawley C, Hay SI, Hay RJ, Henry NJ, Heredia-Pi IB, Hernandez JM, Heydarpour P, Hoek HW, Hoffman HJ, Horita N, Hosgood HD, Hostiuc S, Hotez PJ, Hoy DG, Htet AS, Hu G, Huang H, Huynh C, Iburg KM, Igumbor EU, Ikeda C, Irvine CMS, Jacobsen KH, Jahanmehr N, Jakovljevic MB, Jassal SK, Javanbakht M, Jayaraman SP, Jeemon P, Jensen PN, Jha V, Jiang G, John D, Johnson SC, Johnson CO, Jonas JB, Jürisson M, Kabir Z, Kadel R, Kahsay A, Kamal R, Kan H, Karam NE, Karch A, Karema CK, Kasaeian A, Kassa GM, Kassaw NA, Kassebaum NJ, Kastor A, Katikireddi SV, Kaul A, Kawakami N, Keiyoro PN, Kengne AP, Keren A, Khader YS, Khalil IA, Khan EA, Khang YH, Khosravi A, Khubchandani J, Kiadaliri AA, Kieling C, Kim YJ, Kim D, Kim P, Kimokoti RW, Kinfu Y, Kisa A, Kissimova-Skarbek KA, Kivimaki M, Knudsen AK, Kokubo Y, Kolte D, Kopec JA, Kosen S, Koul PA, Koyanagi A, Kravchenko M, Krishnaswami S, Krohn KJ, Kumar GA, Kumar P, Kumar S, Kyu HH, Lal DK, Lalloo R, Lambert N, Lan Q, Larsson A, Lavados PM, Leasher JL, Lee PH, Lee JT, Leigh J, Leshargie CT, Leung J, Leung R, Levi M, Li Y, Li Y, Li Kappe D, Liang X, Liben ML, Lim SS, Linn S, Liu PY, Liu A, Liu S, Liu Y, Lodha R, Logroscino G, London SJ, Looker KJ, Lopez AD, Lorkowski S, Lotufo PA, Low N, Lozano R, Lucas TCD, Macarayan ERK, Magdy Abd El Razek H, Magdy Abd El Razek M, Mahdavi M, Majdan M, Majdzadeh R, Majeed A, Malekzadeh R, Malhotra R, Malta DC, Mamun AA, Manguerra H, Manhertz T, Mantilla A, Mantovani LG, Mapoma CC, Marczak LB, Martinez-Raga J, Martins-Melo FR, Martopullo I, März W, Mathur MR, Mazidi M, McAlinden C, McGaughey M, McGrath JJ, McKee M, McNellan C, Mehata S, Mehndiratta MM, Mekonnen TC, Memiah P, Memish ZA, Mendoza W, Mengistie MA, Mengistu DT, Mensah GA, Meretoja TJ, Meretoja A, Mezgebe HB, Micha R, Millear A, Miller TR, Mills EJ, Mirarefin M, Mirrakhimov EM, Misganaw A, Mishra SR, Mitchell PB, Mohammad KA, Mohammadi A, Mohammed KE, Mohammed S, Mohanty SK, Mokdad AH, Mollenkopf SK, Monasta L, Montico M, Moradi-Lakeh M, Moraga P, Mori R, Morozoff C, Morrison SD, Moses M, Mountjoy-Venning C, Mruts KB, Mueller UO, Muller K, Murdoch ME, Murthy GVS, Musa KI, Nachega JB, Nagel G, Naghavi M, Naheed A, Naidoo KS, Naldi L, Nangia V, Natarajan G, Negasa DE, Negoi RI, Negoi I, Newton CR, Ngunjiri JW, Nguyen TH, Nguyen QL, Nguyen CT, Nguyen G, Nguyen M, Nichols E, Ningrum DNA, Nolte S, Nong VM, Norrving B, Noubiap JJN, O'Donnell MJ, Ogbo FA, Oh IH, Okoro A, Oladimeji O, Olagunju TO, Olagunju AT, Olsen HE, Olusanya BO, Olusanya JO, Ong K, Opio JN, Oren E, Ortiz A, Osgood-Zimmerman A, Osman M, Owolabi MO, Pa M, Pacella RE, Pana A, Panda BK, Papachristou C, Park EK, Parry CD, Parsaeian M, Patten SB, Patton GC, Paulson K, Pearce N, Pereira DM, Perico N, Pesudovs K, Peterson CB, Petzold M, Phillips MR, Pigott DM, Pillay JD, Pinho C, Plass D, Pletcher MA, Popova S, Poulton RG, Pourmalek F, Prabhakaran D, Prasad NM, Prasad N, Purcell C, Qorbani M, Quansah R, Quintanilla BPA, Rabiee RHS, Radfar A, Rafay A, Rahimi K, Rahimi-Movaghar A, Rahimi-Movaghar V, Rahman MHU, Rahman M, Rai RK, Rajsic S, Ram U, Ranabhat CL, Rankin Z, Rao PC, Rao PV, Rawaf S, Ray SE, Reiner RC, Reinig N, Reitsma MB, Remuzzi G, Renzaho AMN, Resnikoff S, Rezaei S, Ribeiro AL, Ronfani L, Roshandel G, Roth GA, Roy A, Rubagotti E, Ruhago GM, Saadat S, Sadat N, Safdarian M, Safi S, Safiri S, Sagar R, Sahathevan R, Salama J, Saleem HOB, Salomon JA, Salvi SS, Samy AM, Sanabria JR, Santomauro D, Santos IS, Santos JV, Santric Milicevic MM, Sartorius B, Satpathy M, Sawhney M, Saxena S, Schmidt MI, Schneider IJC, Schöttker B, Schwebel DC, Schwendicke F, Seedat S, Sepanlou SG, Servan-Mori EE, Setegn T, Shackelford KA, Shaheen A, Shaikh MA, Shamsipour M, Shariful Islam SM, Sharma J, Sharma R, She J, Shi P, Shields C, Shifa GT, Shigematsu M, Shinohara Y, Shiri R, Shirkoohi R, Shirude S, Shishani K, Shrime MG, Sibai AM, Sigfusdottir ID, Silva DAS, Silva JP, Silveira DGA, Singh JA, Singh NP, Sinha DN, Skiadaresi E, Skirbekk V, Slepak EL, Sligar A, Smith DL, Smith M, Sobaih BHA, Sobngwi E, Sorensen RJD, Sousa TCM, Sposato LA, Sreeramareddy CT, Srinivasan V, Stanaway JD, Stathopoulou V, Steel N, Stein MB, Stein DJ, Steiner TJ, Steiner C, Steinke S, Stokes MA, Stovner LJ, Strub B, Subart M, Sufiyan MB, Sunguya BF, Sur PJ, Swaminathan S, Sykes BL, Sylte DO, Tabarés-Seisdedos R, Taffere GR, Takala JS, Tandon N, Tavakkoli M, Taveira N, Taylor HR, Tehrani-Banihashemi A, Tekelab T, Terkawi AS, Tesfaye DJ, Tesssema B, Thamsuwan O, Thomas KE, Thrift AG, Tiruye TY, Tobe-Gai R, Tollanes MC, Tonelli M, Topor-Madry R, Tortajada M, Touvier M, Tran BX, Tripathi S, Troeger C, Truelsen T, Tsoi D, Tuem KB, Tuzcu EM, Tyrovolas S, Ukwaja KN, Undurraga EA, Uneke CJ, Updike R, Uthman OA, Uzochukwu BSC, van Boven JFM, Varughese S, Vasankari T, Venkatesh S, Venketasubramanian N, Vidavalur R, Violante FS, Vladimirov SK, Vlassov VV, Vollset SE, Wadilo F, Wakayo T, Wang YP, Weaver M, Weichenthal S, Weiderpass E, Weintraub RG, Werdecker A, Westerman R, Whiteford HA, Wijeratne T, Wiysonge CS, Wolfe CDA, Woodbrook R, Woolf AD, Workicho A, Xavier D, Xu G, Yadgir S, Yaghoubi M, Yakob B, Yan LL, Yano Y, Ye P, Yimam HH, Yip P, Yonemoto N, Yoon SJ, Yotebieng M, Younis MZ, Zaidi Z, Zaki MES, Zegeye EA, Zenebe ZM, Zhang X, Zhou M, Zipkin B, Zodpey S, Zuhlke LJ, Murray CJL. Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet 2017;390:1211–59.
[58]. Wesselmann U. A new paradigm in chronic bladder pain. J Pain Palliat Care Pharmacother 2014;28:406–8.
[59]. Willert RP, Delaney C, Kelly K, Sharma A, Aziz Q, Hobson AR. Exploring the neurophysiological basis of chest wall allodynia induced by experimental oesophageal acidification - evidence of central sensitization. Neurogastronterol Motil 2007;19:270–8.
[60]. Williams AC, Craig KD. Updating the definition of pain. PAIN 2016;157:2420–3.
[61]. Woolf CJ. Central sensitization: implications for the diagnosis and treatment of pain. PAIN 2011;152:S2–15.
[62]. Zotov V, Jones MN, Mewhort DJK. Contrast and assimilation in categorization and exemplar production. Atten Percept Psychophys 2011;73:621–39.

ICD-11; Classification; Chronic pain; Chronic primary pain; CRPS; CWP; Fibromyalgia; Headache; Orofacial pain; Visceral pain; Musculoskeletal pain; Idiopathic pain; Functional pain

Supplemental Digital Content

Back to Top | Article Outline
© 2018 International Association for the Study of Pain