Purpose: The primary purpose was to examine the measurement properties of the PROMIS-29 to better understand its use in patients undergoing spine surgery. A secondary objective was to calculate a predictive equation between PROMIS-29 and ODI, to allow clinicians and researchers to determine a predicted ODI score based on PROMIS short form scores.
Methods: 719 patients with PROMIS v2.0 and ODI responses were queried from the quality outcomes database. Validity was assessed using coefficient omega, ceiling/floor effects, and confirmatory factor analysis. Multivariable regression predicting ODI scores from PROMIS-29 domains was used to create a predictive equation. Predicted ODI scores were plotted against ODI scores to determine how well PROMIS-29 domains predicted ODI.
Results: Results showed good reliability and validity of PROMIS-29 in patients undergoing lumbar spine surgery: convergent and discriminant validity, low floor/ceiling effects, and unidimensional domains. The conversion equation used 6 PROMIS-29 domains (ODI% = 37.847- 1.475*[PFraw] + 1.842*[PAINraw] + 0.557*[SDraw] - 0.642*[SRraw] + 0.478*[PIraw] + 0.295*[DEPraw]). Correlation between the predicted and actual ODI scores was R = 0.88, R2 = 0.78, suggesting that the equation predicted ODI scores that are strongly correlated with actual ODI scores.
Conclusions: Good measurement properties support the use of PROMIS-29 in spine surgery patients. Findings suggest accurate ODI scores can be derived from PROMIS-29 domains. Clinicians who want to move from ODI to PROMIS-29 can use this equation to obtain estimated ODI scores when only collecting PROMIS-29. These results support the idea that PROMIS-29 domains have the potential to replace disease-specific traditional PROMs.
Keywords: Oswestry Disability Index; PROMIS-29; Patient-reported outcomes; Spine surgery.