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When investigating pain, the basic procedure for clinics everywhere is to give a patient the McGill Pain Questionnaire. This was developed in the 1970s by two doctors, Ronald Melzack and Warren Torgerson, both of McGill University in Montreal, and is still the main tool for measuring pain in clinics worldwide.
Melzack and his colleague, the doctor Patrick Wall of St Thomas’s Hospital in London, had already galvanized the field of pain research in 1965 with their seminal “gate control theory,” a ground-breaking explanation of how psychology can affect the body’s perception of pain. In 1984 the pair went on to write Wall and Melzack’s Textbook of Pain, the most comprehensive reference work in pain medicine. It’s gone through five editions and is currently over 1,000 pages long.
In the early 1970s, Melzack began to list the words patients used to describe their pain and classified them into three categories: sensory (which included heat, pressure, ‘throbbing’ or ‘pounding’ sensations), affective (which related to emotional effects, such as ‘tiring,’ ‘sickening,’ ‘gruelling’ or ‘frightful’) and lastly evaluative (evocative of an experience—from ‘annoying’ and ‘troublesome’ to ‘horrible,’ ‘unbearable’ and ‘excruciating’).
You don’t have to be a linguistic genius to see there are shortcomings in this lexical smorgasbord. For one thing, some words in the affective and evaluative categories seem interchangeable—there’s no difference between ‘frightful’ in the former and ‘horrible’ in the latter, or between ‘tiring’ and ‘annoying’—and all the words share an unfortunate quality of sounding like a duchess complaining about a ball that didn’t meet her standards.
But Melzack’s grid of suffering formed the basis of what became the McGill Pain Questionnaire. The patient listens as a list of ‘pain descriptors’ is read out and has to say whether each word describes their pain—and, if so, to rate the intensity of the feeling. The clinicians then look at the questionnaire and put check marks in the appropriate places. This gives the clinician a number, or a percentage figure, to work with in assessing, later, whether a treatment has brought the patient’s pain down (or up).
A more recent variant is the National Initiative on Pain Control’s Pain Quality Assessment Scale (PQAS), in which patients are asked to indicate, on a scale of 1 to 10, how “intense”—or “sharp,” “hot,” “dull,” “cold,” “sensitive,” “tender,” “itchy,” etc.—their pain has been over the past week.
The trouble with this approach is the imprecision of that scale of 1 to 10, where a 10 would be “the most intense pain sensation imaginable.” How does a patient ‘imagine’ the worst pain ever and give their own pain a number? Middle-class British men who have never been in a war zone may find it hard to imagine anything more agonizing than toothache or a tennis injury. Women who have experienced childbirth may, after that experience, rate everything else as a mild 3 or 4.