(191) Pain assessment tool error rates and subject preference

Abstract

Pain assessment is an integral part of patient evaluation and treatment. Many tools are available for assessing pain, and patients frequently make errors in self-reporting pain. We assessed error rates and pain scale preference in chronic lower back pain subjects undergoing epidural steroid injection (ESI). This prospective cohort study enrolled 100 subjects (48 men, 52 women, mean age: 45.4 years). Subjects completed six different pain assessment tools at three time points during their treatment course (Pre-ESI, 30 minutes post-ESI, 2 weeks post-ESI) including a Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), Visual Analog Scale (VAS), the Brief Pain Inventory (BPI), Short-form McGill Pain Questionnaire 2 (SF-MPQ-2), and Oswestry Disability Index (ODI). Error rates (multiple answers to single-item questions, marking between answers, customized answers, unanswered questions) were calculated for each assessment tool attempted. We found wide variability in error rates with the lowest error rates occurring in SF-MPQ-2 and VDS (3% of completed forms), and the highest error rates in the VAS (27% of completed scales). Amongst multiple-item pain scales, the SF-MPQ-2 had significantly lower error rates compared with the BPI (p<0.001) but not when compared with the ODI (p=0.072). The NRS and SF-MPQ-2 were the top preferred pain assessment tools (12% subject preference for each); however, this preference was not statistically significant when comparing the SF-MPQ-2 vs BPI (p=0.999) or the SF-MPQ-2 vs ODI (p=0.638). Our findings suggest that the SF-MPQ-2 has lower error rates than the BPI and has the same level of preference as the ODI and BPI, making an argument that the SF-MPQ-2 may be a multiple-item pain assessment tool that limits error in self-report and has the same level of patient preference as other common pain assessment tools.