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Smartphone-based real-life activity data for physical performance outcome in comparison to conventional subjective and objective outcome measures after degenerative lumbar spine surgery

Stefanos Voglis, Michal Ziga, A Zeitlberger, Marketa Sosnova, Oliver Bozinov, Luca Regli, David Bellut, Astrid Weyerbrock, Martin N. Stienen & Nicolai Maldaner

abstract Introduction: Outcome assessments after surgery for degenerative lumbar disorders (DLDs) rely on subjective patient-reported outcomes (PROMs). New objective functional capacity tests, like the smartphone-based 6-min walking test (6WT), have been introduced but presumably also do not reflect the patient's real-life functional performance.
Research question: Pilot study to analyze changes in smartphone-based real-life activity data for physical perfor- mance outcome in patients undergoing surgery for DLD.
Material and methods: Prospective observational study of DLD patients. Objective functional capacity and sub- jective outcomes were measured using 6WT and PROMs. Real-life physical performance data were acquired retrospectively using Apple iPhone Health data and compared against objective capacity and subjective outcomes. Results: Eight patients (mean 46 years, 62% male) provided 286.858 smartphone mile counts. PROMs and physical capacity (6WT) significantly improved postoperatively. 6WT results increased from 352m pre-to 555/ 567m at 6/12 weeks postoperatively (p 1⁄4 0.03). For physical performance a linear mixed effect models showed an increase in daily distance in the first 4 months after surgery (slope þ0.178; p < 0.001). However, those increases reversed from 4 until 12 months postoperatively (negative slope estimate of 0.076; p < 0.001). Smartphone- derived physical performance measures showed a positive correlation with corresponding physical capacity in the 6WT (R 1⁄4 0.57,p 1⁄4 0.004) and negative correlations with PROMs (COMI: R 1⁄4 0.62p 1⁄4 0.001; ZCQ-Physical- Function: R 1⁄4 0.68,p < 0.001; ZCQ-Symptom-Severity: R 1⁄4 0.52,p 1⁄4 0.009).
Discussion and conclusion: Smartphone-based real-life activity data allows for longitudinal physical performance assessment. Physical performance correlated with physical capacity and patient's subjective perception of disability. However, physical performance may be more resistant to postoperative longtime change which should consult a more cautious use as objective outcome measure.
   
keywords Smartphone-based accelerometer Objective functional assessment Functional performance Functional capacity
Big data
6-Min walking test
   
citation Voglis S, Ziga M, Zeitlberger A, Sosnova M, Bozinov O, Regli L, Bellut D, Weyerbrock A, Stienen M N, Maldaner N. Smartphone-based real-life activity data for physical performance outcome in comparison to conventional subjective and objective outcome measures after degenerative lumbar spine surgery. Brain and Spine 2022;.
   
type journal paper/review (English)
date of publishing 24-6-2022
journal title Brain and Spine
DOI https://doi.org/10.1016/j.bas.2022.100881
link https://www.sciencedirect.com/science/article/pii/S2772529422000224
contact Martin N. Stienen