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The McGill Pain Index

Reflex Sympathetic Dystrophy

Health Literacy:  Impact on Pain Intensity

Study: Health Literacy, Pain Intensity and Pain Perception in Patients with Chronic Pain

Hospitals in Vienna, Austria conducted a study of 121 outpatients who suffer chronic pain (defined as pain of duration > three months).

Prospectus: To determine if health literacy had a mediator effect on the intensity, perception, or duration of pain.

Findings: Health literacy correlated with lower pain intensity – an effect attributed to better self-management of pain, and more adequate coping strategies.

This is an important objective of integrated care, even though health literacy did not alter pain perception or duration.

Health literacy is a competence that develops continuously: It should be supported from the onset of diagnosis and therapy.

RSD/Causalgia on the McGill Pain Index

The McGill Pain Index assigns a score of 42 points out of a maximum 50 to the disease Reflex Sympathetic Dystrophy (RSD), or causalgia. Reflex Sympathetic Dystrophy is the most painful chronic disease that is known – exceeding even the pain of amputation.

Taxonomy: Causalgia was recognized on the battlefield in the 1860s. Later in 1946 it was renamed Reflex Sympathetic Dystrophy to reflect the physiology knowledge of the day. A more modern name, Complex Regional Pain Syndrome (Type I), recognizes that subsets of the disease exist mediated through other axes such as the central nervous system (CNS) or inflammation, not always through the sympathetic nervous system.

The McGill Pain Questionnaire

The McGill Pain Questionnaire (MPQ) remains a useful instrument for doctors because it is reliable and consistent. It commands wide use both in clinical practice, and in the realm of research on pain and anesthetics. A measure of its abiding interest:

  • In 1971, Ronald Melzack (an experimental psychologist) and Warren Torgerson (a statistician) published On the Language of Pain in the journal Anesthesiology. With this, they began the world's first search for realistic pain descriptors.
  • In 2005, Anesthesiology invited Melzack to reconstruct the origins of the McGill Pain Questionnaire. An absorbing and readable account of his journey appears in Classic Papers Revisited: The McGill Pain Questionnaire, From Description to Measurement.

The 1971 paper from Melzack and Torgerson proposed what was then a novel idea:

It is not only the intensity of pain that matters. Each disease produces a different quality of pain: we have the burning of causalgia; the stabbing or cramping of visceral pain; and so on. The quality of pain provides a key to diagnosis and may even suggest a course of therapy.

The steps since: Melzack and other pain pioneers working at McGill University in Canada organized their pain descriptors into a chart. Patients in a wide variety of settings were asked to complete the chart by selecting words to match their own pain experience. The language of pain was refined and simplified until the chart took its modern shape – the McGill Pain Questionnaire. During the clinical trials, pain scores were obtained from:

Patients in a general hospital pain clinic
The McGill Pain Questionnaire: Major Properties and Scoring Methods
Melzack, 1975 Pain 1(3)

Patients with a confirmed diagnosis of causalgia
Causalgia: Redefinition as a Clinical Pain Syndrome
Tahmoush, 1981 Pain 10(2)

Women during labour
Labour is Still Painful after Prepared Childbirth Training
Melzack et al, 1981 CMAJ 125(4)

Patients in a hospital emergency department
Acute Pain in an Emergency Clinic: Latency of Onset and Descriptor Patterns Related to Different Injuries
Melzack and Wall, 1982 Pain 14(1)

The clinical trials in summary: For any particular disease, the descriptive words chosen by patients were remarkably similar. So were the pain scores. Substantial portions of the words had the same relative positions on a common intensity scale for people from widely divergent social and ethnic backgrounds.

Melzack used the data from the McGill Pain Questionnaire to create a graph called the McGill Pain Index. It is a yardstick to quantify pain. The Index compares three categories of pain: Labour pain, clinical pain syndromes, and pain after trauma or accident. It takes the visual form of a bargraph, as illustrated below.

McGill Pain Index with Academic Citations
Georgena S. Sil
Saskatoon, Canada
Physicist & Technical Writer
Alumnus: University of British Columbia
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Copyright © 2008-2019 Georgena Sil. All Rights Reserved.