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Comment & Response
November 2019

Age-Related Bias in Total Step Count Recorded by Wearable Devices

Author Affiliations
  • 1Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
  • 2Division of Geriatric Medicine and Gerontology, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
  • 3Center on Aging and Health, Johns Hopkins University, Baltimore, Maryland
JAMA Intern Med. 2019;179(11):1602. doi:10.1001/jamainternmed.2019.4707

To the Editor Wearable devices provide clinicians and researchers the opportunity to better understand the health benefits of physical activity at the individual and population levels. Lee and colleagues1 recently analyzed the association between steps and all-cause mortality in a large cohort of older women and found that mortality rates gradually declined with increasing step volumes up to approximately 7500 steps/d. We appreciate the importance of this work to establish recommendations for improving health through daily physical activity; however, there are problems with the underlying methodology that may inadvertently understate the recommended amount of daily steps needed for health benefits.

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