Digital Phenotyping in Patients with Spine Disease: A Novel Approach to Quantifying Mobility and Quality of Life

OBJECTIVE: To identify trends in mobility and daily pain levels among a cohort of patients with clinically diagnosed spine disease. METHODS: Participants with spine disease were enrolled from a general neurosurgical clinic and installed a smartphone application (Beiwe) designed for digital phenotyping to their personal smartphone. This application collected passive meta-data on a minute-to-minute basis, including global positioning system (GPS), WiFi, accelerometer, text and telephone logs, and screen on and off time. The application also administered daily visual analog scale pain surveys. A linear mixed model framework was used to test for associations between self-reported pain and mobility and sociability from the passively collected data. RESULTS: A total of 105 patients were enrolled, with a median follow-up time of 94.5 days; 55 patients underwent a surgical intervention during the follow-up period. The weekly pain survey response rate was 73.2%. By the end of follow-up, the mean change in pain for all patients was -1.3 points (4.96 at the start of follow-up to 3.66 by the end of follow-up). Increased pain was significantly associated with reduced patient mobility as measured using 3 daily GPS summary statistics (i.e., average flight length, maximum diameter travelled, total distance travelled). CONCLUSIONS: Patients with spine disease who reported greater pain had reduced mobility, as measured by the passively collected smartphone GPS data. Smartphone-based digital phenotyping appears to be a promising and scalable approach to assess mobility and quality of life of patients with spine disease.