Wearable technology has become increasingly popular in monitoring health metrics, including sedentary behavior, particularly among older adults with cardiovascular conditions. This validation study published in JMIR Cardio assesses the accuracy of a consumer-grade wrist-worn activity tracker, specifically the Fitbit Inspire 3, in measuring sedentary time compared to a research-grade waist-worn accelerometer, the ActiveStyle Pro HJA-750C.
Study Overview
The study involved 51 outpatients diagnosed with heart failure or ischemic heart disease, with an average age of 78.4 years. Participants wore both the wrist-worn tracker and the waist-worn accelerometer simultaneously for a period of seven days, during which their sedentary time was measured within a standardized 12-hour window from 9 AM to 9 PM.
Key Findings
The results indicated that the mean sedentary time recorded by the waist-worn accelerometer was 497.9 minutes, while the Fitbit recorded a higher mean of 559.9 minutes. The correlation between the two devices was strong (r=0.905), suggesting that the Fitbit could reliably measure sedentary time. However, the Fitbit showed a significant fixed bias, overestimating sedentary time by approximately 62 minutes.
Despite this overestimation, the study found that after applying a constant bias correction, the concordance between the two devices improved significantly, indicating that with calibration, consumer-grade wearables can be useful in monitoring sedentary behavior in clinical settings.
Implications for Clinical Practice
The findings support the potential for using consumer-grade devices like the Fitbit for scalable monitoring in ambulatory cardiac care. However, the wide limits of agreement between the two devices highlight the need for caution when interpreting individual-level data. The population-specific correction factor identified in this study requires further validation before being applied to different patient populations.
What this study does not show
This study does not demonstrate the effectiveness of using the Fitbit for individual health outcomes or its applicability across diverse populations outside of the studied group.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Established
- Clinical utility: Partial
The evidence class is primary_research with human status unclassified.