Usefulness of step counts to predict mortality in Japanese patients with heart failure

Kazuhiro P. Izawa, Satoshi Watanabe, Koichiro Oka, Koji Hiraki, Yuji Morio, Yusuke Kasahara, Peter H. Brubaker, Naohiko Osada, Kazuto Omiya, Hiroyuki Shimizu

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Abstract

The purpose of this study was to determine both an association between mortality and physical activity (PA) objectively measured by accelerometer and cutoff values for PA in Japanese outpatients with heart failure (HF). This prospective observational study comprised 170 HF outpatients (mean age, 65.2 years; 77% men). Peak oxygen uptake (VO2) and the relation between ventilation and carbon dioxide production (VE/VCO2 slope) as indices of exercise capacity were measured during cardiopulmonary exercise testing with a cycle ergometer. PA was assessed by accelerometer-measured average step count (steps) per day for 1 week. Study endpoint was cardiovascular-related death. Over an average follow-up of 1,377.1 (median, 1,335) days, 31 cardiovascular-related deaths occurred. Patients were then divided into survivor (n = 139) and nonsurvivor (n = 31) groups. Brain natriuretic peptide level was significantly different between groups. Peak VO2 and steps were also significantly lower and VE/VCO2 slope higher in the nonsurvivors versus survivors. Univariate Cox proportional hazards analysis showed brain natriuretic peptide, peak VO2, VE/VCO2 slope, and steps to be significant prognostic indicators of survival. Multivariate analysis showed PA of ≤4,889.4 steps/day to be a strong and independent predictor of prognosis (hazard ratio: 2.28, 95% confidence interval: 1.31-6.30; p = 0.008). Kaplan-Meier curves after log-rank test showed significant prognostic difference between PA of ≤4,889.4 and >4,889.4 steps/day in the 2 groups (log-rank: 12.19; p = 0.0005). In conclusion, step count as objectively measured by accelerometer may be a prognostic indicator of mortality in Japanese outpatients with HF.

Original languageEnglish
Pages (from-to)1767-1771
Number of pages5
JournalAmerican Journal of Cardiology
Volume111
Issue number12
DOIs
Publication statusPublished - 2013 Jun 15

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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    Izawa, K. P., Watanabe, S., Oka, K., Hiraki, K., Morio, Y., Kasahara, Y., Brubaker, P. H., Osada, N., Omiya, K., & Shimizu, H. (2013). Usefulness of step counts to predict mortality in Japanese patients with heart failure. American Journal of Cardiology, 111(12), 1767-1771. https://doi.org/10.1016/j.amjcard.2013.02.034