Association of Perioperative Steps and Heart Rate Variability from Wearable Devices with Surgical Outcomes

BACKGROUND: Surgical recovery is dependent on physiologic reserve, functional capacity, and wellness status. We sought to delineate the association of perioperative changes in daily steps, heart rate variability (HRV), and self-reported wellness with length of stay, complications and readmissions. STUDY DESIGN: Adults undergoing inpatient surgery with ≥30 preoperative and ≥30 postoperative days of data were identified from the All of Us database. Exposures included postoperative changes in daily steps and heart rate variability (HRV) relative to their preoperative baseline. Wellness, using the "SPADE" composite score was examined in a sensitivity analysis. Multivariable regression analyses, adjusted for relevant factors, were used to assess outcomes, including length of stay (LOS), 30-/90-day complications, and readmissions. RESULTS: Among 66,345 patients who underwent a surgical procedure, 1,965 patients (mean age 50.4 years, 69.5% female) were included in the final analytic cohort. Each postoperative +1,000 steps/day relative to preoperative baseline was associated with reduced LOS (incidence rate ratio [IRR]=0.94, 95%CI 0.90-0.99) and lower odds of 30-day (adjusted odds ratio [aOR]=0.83, 95%CI 0.69-1.00) and 90-day (aOR=0.82, 95%CI 0.70-0.96) complications. Incremental increases in steps were also associated with lower odds of 30-day (aOR=0.85, 95% CI 0.76-0.96) and 90-day readmission (aOR=0.84, 95%CI 0.75-0.94). Postoperative HRV changes and self-reported wellness were not associated with any post-operative outcome (p>0.05). CONCLUSIONS: Postoperative step count was the most actionable correlate of recovery across endpoints, whereas postoperative HRV change and self-reported wellness conferred limited independent prognostic value. These findings support integrating wearables into ERAS as preoperative HRV-informed triage and postoperative step-guided recovery, while emphasizing less reliance on subjective patient reported measures to inform discharge or clinical decisions.