Are patient-reported outcome measures biased by method of follow-up? Evaluating paper-based and digital follow-up after lumbar fusion surgery.

BACKGROUND CONTEXT: Long-term follow-up of patient-reported outcome measures (PROM) is essential in both modern spinal care and research. Lack of time and staff are commonly reported barriers to implementing long-term follow-up of PROM. Automated and digital follow-up systems for PROM collection are seeing widespread use, yet their validity and comparative effectiveness have never been evaluated.

PURPOSE: The present study aimed to assess the validity of digital follow-up systems in comparison with the conventional paper-based follow-up (PB-FU).

STUDY DESIGN: This is a retrospective analysis of prospectively collected double follow-up data.

PATIENT SAMPLE: Patients who underwent lumbar spinal fusion for spondylolisthesis or degenerative disc disease between 2013 and 2016 were included in the study.

OUTCOME MEASURES: The study determined the Oswestry Disability Index (ODI) and Numeric Rating Scale (NRS) for back and leg pain severity at baseline, 6 weeks, 12 months, and 24 months.

MATERIALS AND METHODS: After lumbar spinal fusion surgery, a double follow-up of PROM was carried out by conventional PB-FU during clinical visits, while simultaneously completing an automatically dispatched digital follow-up questionnaire. As the primary end point, we assessed the intraindividual discrepancy in PROM between PB-FU and automated digital follow-up (AD-FU).

RESULTS: Forty patients completed all parts of the dual follow-up trajectory and were analyzed. We detected no discrepancy in ODI or NRS for back and leg pain severity at any of the baseline, 6-week, 12-month, or 24 month follow-ups (all p>.05). This was confirmed in a sensitivity analysis.

CONCLUSIONS: In an analysis of dual paper-based and digital follow-up after lumbar fusion surgery, patients report highly similar values using either method of follow-up. It appears that AD-FU without incentives produces lower response rates. To reassess the validity of these systems for data collection in spinal patient care, a prospective validation with higher statistical power is warranted.