Pain Basics

Definition of pain

Key points

  • Pain describes physical suffering or discomfort associated with actual or potential tissue damage.1
  • The 11th revision of the International Classification of Diseases (ICD-11) has recognised chronic pain as a disease in its own right.2,3
  • The biopsychosocial pain model illustrates the various sensorial, cognitive/affective and interpersonal factors that impact chronic pain.4

The International Association for the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”.1 Acute pain is often related to acute injury and trauma and resolves within 3–6 months; it serves as the body’s warning system.5 In comparison, pain that exceeds this time frame can be considered chronic and can either develop when the pain associated with an injury or trauma persists even after the injury has been physically healed or without any apparent stimulus.5 In these cases, where chronic pain represents a disease in itself, it is classified as chronic primary pain. Patients may also experience chronic secondary pain, which arises due to an underlying disease (e.g. arthritis).3,6 In contrast to acute pain, chronic pain usually fulfils no adaptive purpose.6

Chronic pain is influenced by a number of processes that, in turn, strongly affect pain.4 The biopsychosocial pain model (Figure 1) provides a framework to understand the multifaceted nature of chronic pain, with biological, psychological and social factors at play and leading to reduced health-related quality of life.4

Figure 1: Biopsychosocial model of chronic pain and consequences on the quality of life

[Adapted from Dueñas et al. 2016.4]