Intraindividual pain variability in chronic pain: A systematic review

Area of Science:

• Pain research
• Nociplastic pain mechanisms
• Systematic review methodology

Background:

• Chronic pain conditions often exhibit fluctuating pain intensity.
• Intraindividual pain variability is a poorly understood phenomenon.
• Nociplastic pain mechanisms are increasingly recognized in various chronic pain states.

Purpose of the Study:

• To systematically review empirical evidence on intraindividual pain intensity variations in long-term pain.
• To synthesize findings across diverse chronic pain conditions with nociplastic pain.

Main Methods:

• Systematic literature search of Medline for longitudinal, non-interventional studies.
• Inclusion of adult human subjects with chronic pain and nociplastic pain mechanisms.
• Independent dual-reviewer screening and full-text review of study eligibility.

Main Results:

• 13 studies met eligibility criteria from 1195 initial results.
• Consistent evidence of intraindividual pain variability found across nociplastic pain conditions (fibromyalgia, low back pain, TMD, osteoarthritis).
• Patient clustering based on pain variability degree was possible in several studies.

Conclusions:

• Intraindividual pain intensity variability is evident in nociplastic pain conditions, independent of specific diagnosis.
• Pain variability may be clinically relevant, potentially correlating with mental health, fatigue, activity levels, and treatment response.