Smartphone GPS signatures of patients undergoing spine surgery correlate with mobility and current gold standard outcome measures

Abstract

OBJECTIVE Patient-reported outcome measures (PROMs) are currently the gold standard to evaluate patient physical performance and ability to recover after spine surgery. However, PROMs have significant limitations due to the qualitative and subjective nature of the information reported as well as the impossibility of using this method in a continuous manner. The smartphone global positioning system (GPS) can be used to provide continuous, quantitative, and objective information on patient mobility. The aim of this study was to use daily mobility features derived from the smartphone GPS to characterize the perioperative period of patients undergoing spine surgery and to compare these objective measurements to PROMs, the current gold standard. METHODS Eight daily mobility features were derived from smartphone GPS data in a population of 39 patients undergoing spine surgery for a period of 2 months starting 3weeks before surgery. In parallel, three different PROMs for pain (visual analog scale [VAS]), disability (Oswestry Disability Index [ODI]) and functional status (Patient-Reported Outcomes Measurement Information System [PROMIS]) were serially measured. Segmented linear regression analysis was used to assess trends before and after surgery. The Student paired t-test was used to compare pre- and postoperative PROM scores. Pearson’s correlation was calculated between the daily average of each GPS-based mobility feature and the daily average of each PROM score during the recovery period. RESULTS Smartphone GPS features provided data documenting a reduction in mobility during the immediate postoperative period, followed by a progressive and steady increase with a return to baseline mobility values 1 month after surgery. PROMs measuring pain, physical performance, and disability were significantly different 1 month after surgery compared to the 2 immediate preoperative weeks. The GPS-based features presented moderate to strong linear correlation with pain VAS and PROMIS physical score during the recovery period (Pearson r > 0.7), whereas the ODI and PROMIS mental scores presented a weak correlation (Pearson r approximately 0.4). CONCLUSIONS Smartphone-derived GPS features were shown to accurately characterize perioperative mobility trends in patients undergoing surgery for spine-related diseases. Features related to time (rather than distance) were better at describing patient physical and performance status. Smartphone GPS has the potential to be used for the development of accurate, noninvasive and personalized tools for patient mobility monitoring after surgery.

Feasibility and Acceptability of a Preoperative Multimodal Mobile Health Assessment in Spine Surgery Candidates

“…3,[21][22][23] In recent years, several groups have used accelerometer data to measure patient activity as a tool for quantifying objective changes after surgery. 11,12,14,15 By comparison, we have focused on investigating a rigorous, multimodal, multidimensional preoperative protocol that may predict surgical outcome and guide perioperative treatments, such as psychosocial interventions and targeted prehabilitation. 24 This study reports the feasibility and acceptability of this novel assessment.…”

“…Studies to date have focused on prolonged perioperative activity monitoring as a way of objectively measuring surgical outcomes. 11,12,14,15 These efforts have typically used activity data from smartphones or, rarely, participants' own wearable trackers. 13 Although such efforts have clear value, the prognostic importance of isolated preoperative activity measures and their use in guiding perioperative interventions remain unknown.…”

“…To date, most mHealth studies in spine surgery patients have focused on using activity to objectively measure surgical outcome. [11][12][13][14][15] Nonetheless, growing evidence suggests that the relationship between activity and pain is variable across patients, 16 and it is unknown whether preoperative activity levels alone significantly predict surgical outcome. Consequently, a more personalized approach that integrates physiological, functional, and patientreported data may more effectively predict surgical outcome and guide perioperative management.…”

Digital Biomarkers and the Evolution of Spine Care Outcomes Measures: Smartphones and Wearables

“…3,27 Many commonly used PROs, such as the visual analog scale (VAS), Oswestry Disability Index (ODI), and Patient-Reported Outcomes Measurement Information System, have been shown to have low correlation with one another, implicating that scores cannot be compared across PROs, adding to the difficulty in multi-institutional analyses. 26 In addition, incorporating PROs often requires specialized personnel, licensing, and a significant amount of dedicated time, which can cost a practice between $50,000 and $150 000 per annum, depending on the clinic size. 7,15 Falavigna et al 5 found that 31.9% of AOSpine surgeons do not routinely use PROs and cite the aforementioned challenges as major limitations.…”

Personalized Medicine in Orthopaedic Surgery: The Case of Spine Surgery

“…Patients' personal smartphone Global Positioning System (GPS) data were recently studied to evaluate how these metrics are compared with standard patient-reported outcomes measures. 32 Boaro et al 32 demonstrated that smartphone GPS features accurately predicted mobility and correlated with patient-reported outcomes. The use of widely available apps such as Apple Health has also been studied after spine surgery and demonstrated their feasibility in supplementing current outcome scores.…”