Definition of chronic postsurgical pain in the ICD-11: a narrative review of implications for anaesthesiology and pain medicine

Chronic postsurgical pain (CPSP) is associated with reduced health-related quality of life and disability. In some patients, it can result in long-term opioid use even after minor surgery. Epidemiological studies have reported highly varying rates of CPSP, largely because researchers have used different definitions with self-defined cut-offs for pain scores. With the introduction of the 11th revision of the World Health Organisation International Classification of Diseases and Related Health Problems (ICD-11), chronic pain is now recognised as an entity of its own, its biopsychosocial nature is emphasised, and its definition is standardised. Compared with the ICD-11 definition, the prevalence of CPSP might have been overestimated in previous studies. The ICD-11 provides a multifactorial assessment of pain severity, referring to pain intensity, pain-related interference, and pain-related distress, which cover the biopsychosocial aspects of chronic pain. These three scores can be added as extension codes to any pain diagnosis. Harmonisation of the CPSP criteria within the different coding levels of the ICD-11 might improve discrimination of CPSP from other chronic pain conditions not induced by surgery. Although neuropathic CPSP increases pain severity and requires alternative therapeutic approaches to nociceptive pain, a specific code to differentiate between neuropathic and non-neuropathic CPSP is not available. For clinical practice and research, the evidence-based ICD-11 definition, which provides clear-cut diagnostic criteria, should generally be used instead of pain scores alone. This will improve the comparability of data, form the basis for future diagnostic and therapeutic approaches, and facilitate communication.