What Can Legacy Patient-Reported Outcome Measures Tell Us About Participation Bias in Patient-Reported Outcomes Measurement Information System Scores Among Lumbar Spine Patients?

Objective: Patient-Reported Outcomes Measurement Information System (PROMIS) is a validated tool for assessing patient-reported outcomes in spine surgery. However, PROMIS is vulnerable to nonresponse bias. The purpose of this study is to characterize differences in patient-reported outcome measure scores between patients who do and do not complete PROMIS physical function (PF) surveys following lumbar spine surgery.

Methods: A prospectively maintained database was retrospectively reviewed for primary, elective lumbar spine procedures from 2015 to 2019. Outcome measures for Patient Health Questionnaire-9 (PHQ-9), visual analogue scale (VAS) back & leg, Oswestry Disability Index (ODI), and 12-item Short Form health survey physical composite summary (SF-12 PCS) were recorded at both preoperative and postoperative (6 weeks, 12 weeks, 6 months, 1 year, 2 years) timepoints. Completion rates for PROMIS PF surveys were recorded and patients were categorized into groups based on completion. Differences in mean scores at each timepoint between groups was determined.

Results: Eight hundred nine patients were included with an average age of 48.1 years. No significant differences were observed for all outcome measures between PROMIS completion groups preoperatively. Postoperative PHQ-9, VAS back, VAS leg, and ODI scores differed significantly between groups through 1 year (all p < 0.05). SF-12 PCS differed significantly only at 6 weeks (p = 0.003).

Conclusion: Patients who did not complete PROMIS PF surveys had significantly poorer outcomes than those that did in terms of postoperative depressive symptoms, pain, and disability. This suggests that patients completing PROMIS questionnaires may represent a healthier cohort than the overall lumbar spine population.