Introduction: Quality of life and cost-effectiveness are important outcome measures in adult spine surgery. The patient-reported outcomes measurement information system (PROMIS) Global Health Scale (GHS) questionnaire is widely utilized but cannot be factored into cost-effectiveness, creating a barrier to improvement. Previous studies have proposed transformations of PROMIS-GHS to EuroQol (EQ-5D-3L) questionnaire data, which can be utilized to assess cost-effectiveness. However, such methods were not developed specifically in adult spine patients and thus may not be valid.

Methods: PROMIS-GHS and EQ-5D-3L were administered in random order to 52 consecutive adult spine patients, 46 of which were unambiguously completed and thus included. Demographics were also collected. EQ-5D-3L index values were calculated according to a validated United States value set. Our dataset was randomly partitioned into a training (n = 40) and a testing (n = 6) subset. Linear regression was utilized to develop a transformation and Bland-Altman agreement analysis was utilized to assess comparability between our model, previously reported models, and the observed EQ-5D-3L index values.

Results: The average age of our cohort was 60 +/- 14 years (range 21 - 85), 70% were female, and 95% completed at least high school. Linear regression produced a novel model in which three out of ten PROMIS-GHS items (general health, quality of life, and physical activities) were statistically significant indicators of EQ-5D-3L index values. Bland-Altman agreement analysis between our model, previously reported models, and the observed EQ-5D-3L index values revealed a substantial range of agreement.

Conclusions: To our knowledge, this study represents the first prospective validation study of transformations between PROMIS-GHS and EQ-5D-3L index values in adult spine patients. Our analysis suggests the existence of alternative linear models that appear to demonstrate agreement with previously established models. However, further studies with larger samples sizes are needed.

Patient Care: Our research is bridging the gap between different quality of life measurement tools, the results of which can be applied with high-confidence in future cost-effectiveness studies to better understand the relative impact and value of interventions on patient satisfaction and quality of life, among others factors.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of validating literature methodology before implementing it.

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