175. Discrepancy in patient-reported pain using the numeric pain scale and a percentage change to quantify treatment effectiveness after pain injections

BACKGROUND CONTEXT The Numeric Pain Rating Scale (NRPS) may not match with patient-reported percentage pain reduction (PRPPP) at 1 to 4 weeks follow-up, as these patients may be reporting a higher estimated percentage improvement compared to the value calculated from their pain scores PURPOSE The objective of this study was to calculate patients’ pain level prior to and after various fluoroscopic injections using the NRPS. The calculated percent change was then compared to a patient-reported percent change. Our hypothesis was that there is a statistically significant difference in calculated NRPS vs patient-reported percentage change. The discrepancy between calculated percent change compared to the patient reported percent change was studied since accurately assessing patient reported pain impacts clinical management of patients with chronic musculoskeletal pain STUDY DESIGN/SETTING This is a retrospective study using patient reported pre- and postinjection NRPS value were used to calculate a percent change in overall pain ([pre-post)/post] x 100). The calculated percent change was rounded to the nearest degree. This calculated percent change in pain was compared to the patient reported percent change (calculated % - reported %). An overall average change in calculated minus reported percent change was obtained for all the injections. A t-test was also performed to determine if there was a significant difference between the calculated percent change and the reported percent change. PATIENT SAMPLE A total of 135 patients were included. OUTCOME MEASURES The patient reported pre- and postinjection NRPS value were used to calculate a percent change in overall pain ([pre-post)/post] x 100). This calculated percent change in pain was compared to the patient reported percent change (calculated % - reported %). METHODS A total of 135 patients who underwent spinal corticosteroid injections under fluoroscopic-guidance between 2015 and 2017 were retrospectively reviewed. The patient reported pre- and postinjection NRPS value were used to calculate a percent change in overall pain ([pre-post)/post] x 100). This calculated percent change in pain was compared to the patient reported percent change (calculated % - reported %). An overall average change in calculated minus reported percent change was obtained for all the injections. Univariate analysis was utilized to compare the calculated percent change and the reported percent change. RESULTS Data from 135 patient charts was analyzed with a total of 144 injections. This study included 36 males and 99 females. The average patient age was 63.0 years. A total of 42 patients had a BMI >30 and 7 patients had a prior surgical history in the same joint which was injected. Various injections included sacroiliac joint (SI J, n=15), medial branch blocks (MBB, n=21), lumbar transforaminal epidural steroid injections (LTFESI, n=65), lumbar and cervical epidural steroid injections (LESI and CESI, n=25), radiofrequency ablations (RFA), genicular nerve block of the knee, and various shoulder joint injections. The average difference in calculated percent change vs the patient-reported percent change in pain prior to and after the injections was -18.37% (p CONCLUSIONS Effective management of chronic musculoskeletal pain is important due to its physical, social, and financial burden on patients and the healthcare system. Management of chronic pain is heavily impacted by the meaningful use of various patient reported outcome measures. Health insurance companies use variable percent change in pain level to determine effectiveness of treatment. Our data reflects the existence of a statistically significant difference between calculated percent change in pain using the NRPS as compared to patient reported percent change. Based on this analysis it may be valuable to use other functional and psychosocial outcome measures for chronic pain management. Further studies are needed to assess the combined use of the different outcome measures. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.