Abstract
OBJECTIVE: The Graded Chronic Pain Scale (GCPS) is frequently used in pain research and treatment to classify mild, bothersome, and high impact chronic pain. This study's objective was to validate the revised version of the GCPS (GCPS-R) in a US Veterans Affairs (VA) healthcare sample to support its use in this high-risk population. METHODS: Data were collected from Veterans (n = 794) via self-report (GCPS-R and relevant health questionnaires) and electronic health record extraction (demographics and opioid prescriptions). Logistic regression, adjusting for age and gender, was used to test for differences in health indicators by pain grade. Adjusted odds ratio (AOR) with 95% confidence intervals (CIs) were reported with CIs not including an AOR of 1 indicating that the difference exceeded chance. RESULTS: In this population, the prevalence of chronic pain (pain present most or every day, prior 3 months) was 49.3%: 7.1% with mild chronic pain (mild pain intensity and lower interference with activities); 23.3% bothersome chronic pain (moderate to severe pain intensity with lower interference); and 21.1% high impact chronic pain (higher interference). Results of this study mirrored findings in the non-VA validation study; differences between bothersome and high impact were consistent for activity limitations and present but not fully consistent for psychological variables. Those with bothersome chronic pain or high impact chronic pain were more likely to receive long-term opioid therapy compared to those with no/mild chronic pain. CONCLUSIONS: Findings highlight categorical differences captured with the GCPS-R, and convergent validity supports use of the GCPS-R in US Veterans.