HPE Chronic pain – part one - Page 4

Currently, there is still a lack of universal understanding and formal definition of ‘pain chronification’. This issue was addressed recently by an international group of pain experts. 10 • Pain chronification describes the process of transient pain progressing into persistent pain • Pain processing changes as a result of an imbalance between pain amplification and pain inhibition • Genetic, environmental and biopsychosocial factors determine the risk, degree and time-course of chronification. The key question: is chronic pain a symptom or a disease? Over the last two decades several pain specialists called to recognise pain as a disease, whereas others have argued against this concept. 11 In 2001, the European Pain Federation (EFIC ® ) claimed in their Declaration on pain that “chronic and recurrent pain is a specific health care problem, a disease in its own right.” 12 The concept that chronic pain is considered to differ from pain as a symptom remains a debated topic in the scientific community. To guide this debate, a pragmatic approach is to start from the definitions of symptom and disease respectively and to check if chronic pain fits into the framework of these definitions. According to the World Health Organization (WHO), a disease is “a particular abnormal condition that negatively affects the structure or function of part or all of an organism, and that is not due to any external injury.... A disease may be caused by external factors such as pathogens or by internal dysfunctions. 13 Significant progress has been made over the last 20 years in unravelling neural mechanisms in the central nervous system that are associated with chronic pain. Substantial functional, structural and chemical changes were demonstrated by advanced neuroimaging studies, such as functional magnetic resonance and PET scans. 14 Pain in these circumstances is not simply a symptom of some distinct disease pathology but rather the expression of a pathologically functioning nervous system. 15 This means that chronic pain is “a particular abnormal condition” and that both the “structure and function of the organism” are negatively affected. Moreover, chronic pain modifies not only physical functioning, but also psychological and social functioning. A major step forward: the ICD-11 The International Classification of Diseases 11th Revision (ICD-11) is the latest update of the global standard for diagnostic health information. 16 In 2012, the IASP Task Force for the Classification of FIGURE 1 Diagnostic criteria for chronic primary pain Conditions A–C are fulfilled: A Chronic pain (persistent or recurrent for longer than 3 months) is present B The pain is associated with at least one of the following: B.1 Emotional distress due to pain is present. B.2 The pain interferes with daily life activities and social participation. C The pain is not better accounted for by another chronic pain condition. 4 | 2019 | hospitalpharmacyeurope.com Chronic Pain developed a new classification of chronic pain, published the proposals and commenced intensive field testing. The ICD-11 was approved on 25 May 2019 and it will come into effect on 1 January 2022. For the first time, the ICD-11 includes seven diagnostic categories of chronic pain. Importantly, one of these categories, termed chronic primary pain (MG30.0), acknowledges chronic pain as a health condition in its own right. In addition, six forms of chronic secondary pain (MG30.1-MG30.6), describe chronic pain that developed as a symptom in the context of an underlying disease such as cancer and rheumatoid arthritis among others. The inclusion of chronic pain in this classification is characterised by clearly operationalised diagnostic criteria and precise definition for each chronic pain diagnosis. Additionally, the different levels of diagnostic detail enable the use of the ICD-11 in a variety of settings, from primary to tertiary care. As discussed above, chronic pain modifies not only physical functioning, but also psychological and social functioning. Notably, the coding of pain and pain-associated disability should be harmonised between ICD-11 and the International Code of Functioning (ICF). 17 This harmonisation would be highly relevant for chronic pain. 18 What is chronic primary pain? ICD-11 has introduced new diagnostic criteria for the coding of chronic pain (see Figure 1). Whereas the diagnostic criteria of chronic secondary pain are mostly straightforward, diagnosing chronic primary pain is more challenging. 19 Chronic primary pain is multifactoral, involving biological, psychological and social factors. The diagnosis is appropriate independently of identified biological or psychological contributors unless another diagnosis would better account for the presenting symptoms. Other chronic pain diagnoses to be considered are: • Chronic cancer-related pain • Chronic post-surgical/post-traumatic pain • Chronic neuropathic pain • Chronic secondary headache/orofacial pain • Chronic secondary visceral pain, and • Chronic secondary musculoskeletal pain. 20 Impact of pain In addition to serious consequences on the patient’s life, chronic pain has severe and profound effects on their social and family environment. Coupled with this, at the societal level, chronic pain leads to frequent use of healthcare and welfare resources, and is one of the leading causes of absence from work. These factors generate a substantial socioeconomic burden derived from both direct and indirect costs (including loss of productivity, compensation payments as a result of the patient’s disability). The experience of pain negatively impacts many aspects of a patient’s life (Table 1). 21 It has been shown that non-cancer chronic pain affects between 10% and 30% of the population across Europe. 22 Effect on the patient and quality of life Chronic pain correlates with reduced physical activity and even disability. 21 Bassols et al 23 showed that in individuals with chronic back pain, only approximately 32% were able to perform daily activities. TABLE 1 Negative impact of chronic pain Psychological • Depression • Sleep disturbances • Anxiety • Ability to cope • Fear Social • Social interactions/ network • Family • Work Quality of life • Mental health • Social functioning • Physical functioning • Impact on general daily activities