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Canadian Journal of Cardiology

WEARABLE ACTIVITY TRACKERS PROVIDE VALUABLE INSIGHT INTO SEASONAL AND SCHOOL-RELATED PHYSICAL ACTIVITY PATTERNS IN CHILDREN WITH CONGENITAL HEART DISEASE

      Background

      Objective evaluation of physical activity levels in children with congenital heart disease (CHD) is of increasing interest in the clinical context. Wearable activity trackers have recently been validated in children with CHD. We aimed to illustrate their value to gain insight into activity patterns in children with CHD.

      Methods

      We recruited participants (9-18yrs, CHD or cardiac transplant) from pediatric cardiology clinics in BC, Canada. Participants wore an activity tracker for 16 weeks (FitBit Charge HR). In this analysis we included 23 participants who had detailed min-by-min Fitbit data available through the fee-for-service Fitabase. We included days with ≥600 min/day of device wear time, defined based on heart rate signal. For each participant and measurement days, we identified school schedules and obtained climate records in relation to their home. We performed mixed linear regression to assess daily step patterns (adjusting for multiple days per person), and in relation to potential explanatory factors (Stata v.14, p < 0.05).

      Results

      Participants were 14.3±2.3yrs old, 48% were female and 30% were overweight or obese. Ten had mild CHD, 5 moderate CHD, 6 severe CHD and there were 2 cardiac transplant recipients. We included 1,612 valid person-days (mean 70±23 days/person). Loss of days was predominantly due to technical error (loss of min-by-min data due to infrequent device syncing; 32% of possible days); few days had insufficient wear time (5%). Overall, mean daily steps were 9,507+2,243, and 9% of the variance in daily steps were explained by age, sex and diagnosis (mild CHD were least active). Weight status was not related to steps. Twenty-two % of measurement days fell on days during school break, when steps were significantly lower compared with days when school was in session (-1,144 steps/day, p < 0.001). Daily steps were significantly lower on weekends compared with schooldays (-2,446 steps/day, p < 0.001). On school days, approximately 63% of the daily steps were accrued during school hours (8am-4pm). School-based steps were not affected by changes in climate during the measurement period, but there were positive associations between outside temperature and after school/evening steps (4-8pm; p < 0.001), daily steps at the weekend (p=0.045) and daily steps during school break (p=0.021).

      Conclusion

      Wearable activity trackers provide important insight to activity patterns in children with CHD. School is a constant source of physical activity in these children with CHD throughout the year, irrespective of disease severity. In children with low activity levels, school is the primary source of physical activity.
      Heart and Stroke Foundation, BC & Yukon