Introduction

Commercially available activity trackers are becoming more popular and provide opportunities to track patients? vital signs remotely.

Aim

To explore the validity of Fitbit to measure daily steps, oxygen saturation (SpO₂) and resting heart rate (RHR) in patients with COPD.

Methods

Patients wore Fitbit and (1) Dynaport MoveMonitor (DAM) (daily steps); (2) Nonin WristOX₂ 3150 (SpO2) and (3) Polar H10 (RHR). The agreement between day-by-day measures of Fitbit and corresponding gold-standard devices was evaluated via intraclass correlation coefficient (ICC), paired t-test and Pearson correlation.

Results

Assessment of 25 patients (80% male, age 70±6y, FEV₁ 52±15%pred, 5732±3278 steps/day, 71±9 bpm RHR, 91±2% SpO₂) resulted in 170, 44 and 39 patient-days for respectively steps, RHR and SpO₂. Data showed good agreement for steps (ICC=0.82;95%CI 0.55-0.91) and RHR (ICC=0.85;95%CI 0.71-0.92) and moderate agreement for SpO₂ (ICC=0.49;95%CI -0.21-0.81). Mean steps and SpO₂ were significantly higher compared to DAM and Nonin (+1719±2451steps/day;p<0.001, +3.03±1.67%;p<0.001) whereas mean RHR was significantly lower compared to Polar (-2.12±6.10bpm;p=0.03). Correlations were strong (fig 1).

Conclusion

Although Fitbit Charge 4 shows moderate to good agreement, measures of steps, RHR and SpO₂ deviated from gold-standard methods. Future research should examine its validity to pick up day-by-day changes.