People with heart failure (HF) who increase their daily step count also saw improvements in their health status over a 12-week period, according to a study published July 26 in JACC: Heart Failure. The study suggests that physical data from wearable devices, such as step count, may be clinically significant and has the potential to inform future clinical trials and clinical care.

Jessica Golbus, MD, MS, et al., used data from the CHIEF-HF trial – a randomized controlled trial that provided all participants with a Fitbit and asked them to complete serial Kansas City Cardiomyopathy Questionnaires through a smartphone application. Researchers evaluated the relationship between daily step count and floors climbed and KCCQ total symptom and physical limitation scores at two weeks as well as their changes over 12 weeks. The study cohort included 425 people with HF, including 44.5% female and 40.9% with HF with reduced ejection fraction.

Results showed that at two weeks, the mean KCCQ-physical limitation score was 55.7 and the KCCQ-total symptom score was 62.7. Physical limitation scores increased by four points on average through 12 weeks and total symptom scores increased by 2.5 points.

Researchers saw higher daily step counts with increased KCCQ scores for both physical limitation and total symptom scores. People with KCCQ-total symptom scores of zero-24 averaged 2,473 steps per day and those with scores of 75-100 averaged 5,351 steps per day. Participants climbed a mean of 2.7 floors per day, but daily floors climbed was not significantly different across different KCCQ score ranges.

Daily step count between 1,000 and 5,000 was significantly associated with symptoms and physical limitations based on KCCQ total symptom and physical limitation scores. Little association was seen once step counts reached higher than 5,000 steps per day. When comparing results to differing step counts, people who walked 1,000 steps per day had KCCQ-total symptom scores that were 3.11 points lower than people who walked 2,000 steps per day. And people who walked 3,000 steps per day had KCCQ-total symptom scores that were 2.89 points higher than those who walked 2,000 steps per day.

Changes in step count over time were also significantly associated with changes in KCCQ scores, suggesting that step count data from a wearable device may be leveraged to inform clinical care, or in the future, as clinical trial endpoints. The study found participants whose step counts increased by 2,000 steps per day saw a 5.2-point increase in their KCCQ-total symptom scores and a 5.33-point increase in their KCCQ-physical limitation scores when compared to participants with no change in step count.

People who saw a decline in their step count had numerical declines in their KCCQ-physical limitation score that were not statistically significant, when compared to participants with no change in step count.

“[Our research showed] increased step counts were significantly associated with improvements in health status, suggesting that increases in step count over time as assessed by a wearable device may be clinically meaningful,” said Golbus.

In a related editorial comment, Mitchell Psotka, MD, PhD, FACC, discusses how actigraphy, or a way to quantify physical movement using step counts, is a promising but not completely realized tool for clinical and research purposes.

“These data are part of a large body of necessary and incremental work that will be required for actigraphy to attempt to achieve its potential as a patient-centered and efficient measure of functional status,” he said. “The authors have thankfully moved our understanding of actigraphy forward, though it is still the new kid on the block and will require substantial further testing and validation prior to widespread reliable clinical and research use.”

Keywords: Wearable Electronic Devices, Stroke Volume, Smartphone

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