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Is the minimal clinically important difference (MCID) in acute pain a good measure of analgesic efficacy in regional anesthesia?
  1. Felipe Muñoz-Leyva1,
  2. Kariem El-Boghdadly2,3 and
  3. Vincent Chan1
  1. 1 Department of Anesthesia & Pain Management, University Health Network, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada
  2. 2 Department of Anaesthesia and Perioperative Medicine, Guy's and St Thomas' NHS Foundation Trust, London, UK
  3. 3 King's College London, London, United Kingdom
  1. Correspondence to Dr Vincent Chan, Anesthesia, University of Toronto Faculty of Medicine, Toronto, ON M5T 2S8, Canada; mail2vincechan{at}


In the field of acute pain medicine research, we believe there is an unmet need to incorporate patient related outcome measures that move beyond reporting pain scores and opioid consumption. The term “minimal clinically important difference” (MCID) defines the clinical benefit of an intervention as perceived by the patient, as opposed to a mathematically determined statistically significant difference that may not necessarily be clinically significant. The present article reviews the concept of MCID in acute postoperative pain research, addresses potential pitfalls in MCID determination and questions the clinical validity of extrapolating MCID determined from chronic pain and non-surgical pain studies to the acute postoperative pain setting. We further suggest the concepts of minimal clinically important improvement, substantial clinical benefit and patient acceptable symptom state should also represent aspirational outcomes for future research in acute postoperative pain management.

  • analgesia
  • pain
  • postoperative
  • pain perception
  • regional anesthesia
  • pain measurement

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  • Contributors FM-L drafted versions of the manuscript, provided figures and edited the manuscript. VC designed the concept of the manuscript, provided figures, drafted versions of the manuscript and edited the manuscript. KE-B provided figures and edited the manuscript. All authors contributed significantly to the elaboration of the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.