title: Usefulness of step counts to predict mortality in Japanese patients with heart failure.
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.
authors.affiliation: Department of Rehabilitation Medicine, St. Marianna University School of Medicine Hospital, Kanagawa, Japan. izawapk@ga2.so-net.ne.jp
authors.forename: Kazuhiro P
authors.initials: KP
authors.lastname: Izawa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Koichiro
authors.initials: K
authors.lastname: Oka
authors.forename: Koji
authors.initials: K
authors.lastname: Hiraki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Morio
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kasahara
authors.forename: Peter H
authors.initials: PH
authors.lastname: Brubaker
authors.forename: Naohiko
authors.initials: N
authors.lastname: Osada
authors.forename: Kazuto
authors.initials: K
authors.lastname: Omiya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis / Q000401:mortality*; D006801:Humans; D007564:Japan; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D045283:Natriuretic Agents / Q000097:blood*; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010045:Outpatients; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D045283:Natriuretic Agents; D020097:Natriuretic Peptide, Brain; D002245:Carbon Dioxide; D010100:Oxygen