In recent years, the use of wearable technology for monitoring health behaviors has gained traction, particularly in the realm of cardiovascular care. This validation study, published in JMIR Cardio, investigates the accuracy of a consumer-grade wrist-worn activity tracker, specifically the Fitbit Inspire 3, in measuring sedentary behavior among older patients with cardiovascular conditions.
Study Overview
The primary aim of this research was to assess the agreement between sedentary time recorded by the Fitbit Inspire 3 and a research-grade waist-worn accelerometer, the ActiveStyle Pro HJA-750C, in a sample of 51 Japanese outpatients diagnosed with heart failure or ischemic heart disease. Participants wore both devices simultaneously for a duration of seven days, providing a comprehensive view of their sedentary behavior during a standardized 12-hour daytime window.
Key Findings
The results indicated that the mean sedentary time recorded by the waist-worn accelerometer was 497.9 minutes, while the Fitbit tracker reported a significantly higher mean of 559.9 minutes. The study found a strong correlation between the two devices (r=0.905), suggesting that while the Fitbit overestimated sedentary time by approximately 62 minutes, it still provided a reliable measure of sedentary behavior.
Further analysis revealed that the Fitbit showed a constant bias but no proportional bias, indicating that the overestimation was consistent across the range of sedentary time measured. After applying a bias correction, the concordance correlation coefficient improved significantly, suggesting that with calibration, consumer-grade wearables could be effectively used for monitoring sedentary behavior in clinical settings.
Implications for Clinical Practice
The findings of this study support the potential for consumer-grade activity trackers to be used in outpatient settings for monitoring sedentary behavior among older adults with cardiovascular disease. However, the authors caution that the wide limits of agreement observed in the study may limit the precision of individual-level assessments. They recommend that the population-specific correction factor identified in this study be validated in other settings before widespread application.
What this study does not show
This study does not establish the effectiveness of using the Fitbit Inspire 3 for individual-level precision in measuring sedentary behavior, as the wide limits of agreement indicate variability that may affect personal health assessments.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Established
- Clinical utility: Partial
The evidence for analytic and clinical validity is based on the strong correlation and agreement analysis performed in the study.