The study set out to develop and test a measure of perceived pain suitable for use in community studies and in the evaluation of clinical care.
The work had three parts; (1) generation and selection of items, (2) weighting of the items and (3) testing for reliability and validity. Potential items were obtained from 230 informal interviews conducted in a variety of settings. These were reviewed to produce a draft questionnaire, and this was used in a pilot study of 60 volunteers to determine the final item selection. Item weights were calculated using ratings of severity as judged by subjects in the pilot study and the validity testing. Weights are used so that questions referring to more severe pains have higher scores than those about milder pains. Reliability and validity testing was carried out using three groups: 100 rheumatoid arthritis outpatients; 37 attenders at an occupational health clinic and 178 chronic pain clinic patients. Scores from the three different patient groups were compared, scores were compared with a visual analogue measure of pain, and scores from the same individuals from two consecutive months were compared.
The main product was the new measure itself, the Glasgow Pain Questionnaire (GPQ). This has a total of 24 items in five categories; pain frequency, intensity, emotional reaction, ability to cope and restrictions of daily activity.
Validity; scores were significantly different in the three groups. The GPQ scores were significantly related to the visual analogue measure of pain. Reliability; scores of the same respondents on two consecutive months were significantly associated and had a modal value of zero.
The project has produced a new measure of self-rated pain suitable for use in large-scale population surveys. This instrument assesses not only pain intensity but affective dimensions of pain. It is considered that the validity and reliability testing carried out to date show the measure as acceptable for use in future studies.