The relationship between pain and disability : a thesis presented in partial fulfilment of the requirements for the Degree of Master of Science in Psychology at Massey University

Abstract

The biopsychosocial model of pain and disability suggests that there are many factors involved in chronic pain and the associated disability. The disability associated with chronic pain impacts on both the individual and society. Disability was traditionally thought to be a direct function of pain. Pain and disability are now understood to be separate but related constructs. Pain intensity is an aspect of pain which is often used to measure the relationship between pain and disability. Pain extent is another aspect of pain which has been previously found to be associated with disability. The overall goal of the present study was to examine the relationship between pain and disability. Participants were 290 chronic pain patients referred to a rehabilitation institute for a functional capacity evaluation, the majority of whom were suffering from back pain or Occupational Overuse Syndrome (OOS). The Oswestry measure of disability, visual analogue scales measuring current, best, and worst pain intensity, pain drawings to measure pain extent, demographic and general information relating to the pain problems was collected. The characteristics of the sample and the back pain and OOS diagnosis groups were examined. Multiple regression analyses were used to explore the relationship between pain and disability and assess the degree to which pain extent might contribute to this relationship. Pain extent was found to be significantly associated with disability but to a lesser degree than pain intensity. Findings suggest that pain is an important aspect of disability, however, it fails to explain it completely. There were several methodological difficulties associated with the present study, particularly the amount of missing data due to inconsistent data collection, and that participants with OOS did not complete the measure of disability. Future research should address these issues and incorporate other factors such as social variables into the analyses.