P126. Psychometric evaluation of PROMIS physical function computer adaptive testing in minimally invasive lumbar spine surgery: an analysis of responsiveness, coverage, discriminant validity and concurrent validity

Abstract

BACKGROUND CONTEXT While ODI has historically been the most commonly used patient-reported outcome measure for patients with lumbar spinal pathology, Patient-Reported Outcome Measurement Information System (PROMIS) is increasingly being utilized. However, there are few studies assessing the psychometric properties of PROMIS in minimally invasive (MIS) spine surgery. PURPOSE To perform a psychometric evaluation of PROMIS Physical Function Computer Adaptive Testing (PROMIS-PF CAT) in MIS lumbar surgery. STUDY DESIGN/SETTING Retrospective review of prospectively collected data. PATIENT SAMPLE A total of 421 patients who underwent MIS lumbar surgery. OUTCOME MEASURES Patient-reported outcome measures [Oswestry disability Index – ODI, PROMIS-PF CAT, Short Form (SF)-12]. METHODS Patient-reported outcome measure (PROMs) collected pre- and post-operatively of patients undergoing MIS lumbar surgery were retrospectively analyzed to assess responsiveness, coverage, discriminant validity and concurrent validity of PROMIS-PF CAT. Responsiveness was assessed using paired t-test, effect size (ES) and standardized response mean (SRM). Coverage was measured by assessing floor and ceiling effects. Discriminant validity was assessed pre- and post-op using independent t-test to identify difference in PROMIS-PF scores in known groups. Concurrent validity was assessed by evaluating the correlation with legacy PROMs, ODI and SF12. RESULTS Responsiveness 1. Decompression cohort: SF-12 PHS and PROMIS-PF have lower responsiveness than ODI in detecting an improvement at 2 weeks; PROMIS-PF also has lower responsiveness in detecting improvement at 1 year. 2. Fusion cohort: ODI and PROMIS-PF demonstrate equivalent responsiveness at all time-points; however, the responsiveness of SF-12 is lower than that of ODI and PROMIS-PF at all time-points. Coverage No floor effect was seen for any PROMs. ODI showed a ceiling effect (% having the best possible score: 0.5% pre-operatively; gradually increasing at 16.7% at 1-year). SF-12 PHS and PROMIS-PF did not show a ceiling effect, and clustering at higher levels was CONCLUSIONS Although PROMIS-PF showed lower responsiveness than ODI, particularly in the decompression sub-group, it demonstrated discriminant validity pre- and post-operatively, convergent validity with ODI and better coverage than ODI. These findings suggest that PROMIS-PF CAT demonstrates reasonable psychometric properties and may be a good surrogate for ODI. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.