Higher daily step counts, measured by actigraphy, were associated with heart failure symptoms and health status, although reductions in step count were not, in a new study.
Daily step counts between 1000 and 5000 were significantly associated with symptoms and physical limitations, as reflected in Kansas City Cardiomyopathy Questionnaire (KCCQ) total symptom (TS) and physical limitation (PL) scores.
Participants whose step count increased by 2000 steps per day showed a 5.2 point increase in their KCCQ-TS score and a 5.33 point increase in their KCCQ-PL score, with higher scores reflecting improvement.
However, decreases in step count were not associated with significant decreases in KCCQ-PL scores.
The results are not yet ready to be implemented in practice, said first author Jessica R. Golbus, MD, of the University of Michigan in Ann Arbor. theheart.org | Medscape Cardiology. But, she said, they “suggest that clinicians should interpret improvements in step counts as signs of improvement in health status, although they should not necessarily be as concerned about reductions in step counts.
“However, I would certainly still encourage clinicians to discuss declining physical activity levels with their patients, even if an intervention is not necessarily warranted,” she added.
The survey was published online July 26 in JACC: Heart failure.
The researchers analyzed data from Canagliflozin: Impact on Health Status, Quality of Life and Functional Status in Heart Failure (CHIEF-HF), a randomized controlled trial that enrolled participants with heart failure who had a smartphone.
Participants were given a Fitbit Versa 2 and completed serial KCCQs via the smartphone app.
The researchers assessed the relationship between daily step count and KCCQ-TS and KCCQ-PL scores at baseline, as well as changes in scores between 2 and 12 weeks.
The study included 425 patients. The mean age was 63.5 years, 44.5% were female, and 83.3% were white; 40.9% had reduced ejection fraction, 59.1% had preserved ejection fraction, and 27.5% had type 2 diabetes.
After 2 weeks, the mean KCCQ-TS score was 62.7 and the mean KCCQ-PL score was 55.7.
KCCQ-TS scores increased by an average of 2.5 points and KCCQ-PL scores by 4 points over 12 weeks.
When categorized by 25-point intervals, the number of steps increased with increasing scores for both KCCQ-TS and KCCQ-PL. Those with KCCQ-TS scores of 0 to 24 averaged 2437.6 steps per day, and those with scores of 75 to 100 averaged 4870.9 steps per day.
Similarly, participants with KCCQ-PL scores of 0 to 24 averaged 2301.5 steps per day, and those with scores of 75 to 100 averaged 5351.9. The relationship remained significant after adjustment.
There were non-linear associations between activity and KCCQ scores: daily step counts below 5000 steps were associated with KCCQ scores, but there was little association with counts above 5000 steps.
Compared to participants who walked 2000 steps per day, those who walked 1000 had KCCQ-TS scores that were 3.11 points lower; participants who walked 3000 had KCCQ-TS scores that were 2.89 points higher.
Similarly, participants who walked 1000 steps per day had KCCQ-PL scores that were 5.36 points lower than those who walked 2000 steps, and those who walked 3000 steps had KCCQ-PL scores that was 4.97 points higher.
After adjustment, change in daily step counts was significantly associated with a change in KCCQ-PL scores from baseline to 12 weeks; for example, participants whose step count increased by 2000 steps per day experienced a 5.33 increase in their KCCQ-PL score compared to participants whose step count did not change.
“New Kid on the Block”
Frederick Ho, PhD, a lecturer in public health at the University of Glasgow who is a volunteer spokesman for the American Heart Association, called the study “promising.”
“The follow-up of the study is relatively short, so it is not known whether the association is valid in the long term,” he said theheart.org | Medscape Cardiology. “It is also possible that patients with more severe symptoms became physically less active, and at the same time had worse results.
“A study with longer follow-up among patients from a wider background would give confidence in the generalizability of the findings,” said Ho, who led a recent study that showed accelerometer-measured physical activity was associated with a lower risk of heart failure. “It would also be interesting to validate the results using different types of wearable devices.”
Previous studies have shown that wrist-worn wearables can overestimate light-intensity activities compared to hip-worn devices, he noted. “I would imagine the results would be slightly different due to different types of devices, but the overall premise should remain.”
In a related editorialMitchell Psotka, MD, PhD, writes that Golbus and colleagues “fortunately have moved our understanding of actigraphy forward, although it is still the new kid on the block and will require significant additional testing and validation before widespread reliable clinical and research use.”
Terminology and reporting capabilities need to be standardized, and preferred deployment methods need to be established, including how to wear the devices, he suggests.
Further research is needed to validate that “accelerometers and their digitally processed motion ‘counters’ actually measure activity and that this measured activity has clinical relevance.”
The study did not receive commercial support. Golbus, Ho and Psotka report no relevant relationships.
Follow Marilynn Larkin on Twitter: @MarilynnL.