Purpose: Currently, there is no universally accepted pain classification measure, which can accurately predict the complexity of pain management, particularly for difficult to treat advanced cancer pain. The primary purpose of this study was to gather further validity evidence for the internal structure of the revised Edmonton Staging System (rESS), an innovative cancer pain classification system, using content experts. A secondary purpose was to develop and evaluate an administration manual for the rESS.
Methods: A panel of content experts (n=20), representing palliative medicine and pain specialists within the province of Alberta, Canada, were purposefully selected to participate in a mail-out survey. Quantitative data were analyzed using descriptive statistics, while qualitative data were content analyzed for common themes.
Results: A total of 12 people responded to the survey, representing a response rate of 60%. The average agreement for appropriateness of categories ranged from 4.1 (SD 1.5) for addictive behavior to 4.6 (SD 1.2) for mechanism of pain, on a scale of 1 (strongly disagree) to 5 (strongly agree). The majority of respondents suggested revisions for current definitions, particularly incidental pain, psychological distress and addictive behavior. Of three possible definitions for incidental pain, psychological distress and addictive behavior, existing definitions were ranked first by 58% of respondents.
Conclusions: The overall structure of the rESS appears to provide a comprehensive representation of pain classification. Definitions of terms need to be revised to ensure the accurate and valid use of this measure. A series of validation studies are planned to demonstrate the credibility of the rESS as an internationally recognized reliable and valid pain classification system.