What Constitutes Normal Hemoglobin Concentration in Community-Dwelling Disabled Older Women?

Authors

  • Paulo H. M. Chaves MD, PhD,

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Qian-Li Xue PhD,

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Jack M. Guralnik MD, PhD,

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Luigi Ferrucci MD, PhD,

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Stefano Volpato MD, MPH,

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Linda P. Fried MD, MPH

    1. From the *Johns Hopkins Center on Aging and Health, Departments of Medicine and Epidemiology, Johns Hopkins University, Baltimore, Maryland§UNATI Center for Studies on Aging and Care of the Elderly, Rio de Janeiro State University, (VERJ) Rio de Janeiro, BrazilLaboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MarylandLaboratory of Clinical Investigation, Gerontology Research Center; National Institute on Aging, Baltimore, Maryland#Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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  • Research supported by Contracts N01-AG-1–2112 and R37-AG-1–9905 from the National Institute on Aging.

  • Preliminary results of this study were presented at the 2001 American Geriatrics Society Annual Scientific Meeting, Chicago, IL, and the 2002 American Public Health Association Annual Meeting, Philadelphia, PA.

Paulo H. M. Chaves, MD, PhD, Johns Hopkins Center on Aging and Health, 2024 E. Monument Street, Suite 2–700, Baltimore, MD 21205. E-mail: pchaves@jhsph.edu

Abstract

Objectives: To examine the associations between hemoglobin (Hb) concentration and (1) 5-year all-cause mortality and (2) serum erythropoietin (EPO), as the basis for the identification of data-driven thresholds, and to assess the clinical relevance of mildly low Hb.

Design: Prospective study.

Setting: Population based.

Participants: Community-dwelling women aged 65 and older with moderate-to-severe disability—Women's Health and Aging Study I, Baltimore, Maryland, 1992–2000.

Methods: Proportional hazards regression was used to model the relationship between baseline Hb (available for 686 subjects) and time to death. A generalized linear model was used to assess the cross-sectional association between Hb and EPO in 641 subjects.

Results: A curvilinear slope of steady mortality decrease up to the Hb threshold of 13.9 g/dL was observed. Hb of 11 g/dL was independently associated with greater mortality than the World Health Organization (WHO) low-normal cutoff of Hb of 12 g/dL (hazard ratio (HR)=1.2, 95% confidence interval (CI)=1.1–1.4), whereas Hb of 14 g/dL was linked to 24% lower mortality (HR=0.76, 95% CI=0.63–0.92), after comprehensive adjustment for major health status and disease-burden indicators. A curvilinear, statistically significant slope of steady EPO decrease with increasing Hb up to the threshold of 14.3 g/dL was consistently observed.

Conclusion: The meaningfully lower mortality risk with higher Hb levels provides empirical evidence against the notion that Hb currently perceived as mildly low is clinically benign. Furthermore, the mortality risk gradient observed even within the WHO normal Hb range suggests that Hb levels higher than what is currently recommended might offer clinical advantage. The relationship between Hb and EPO provided supporting physiological evidence for this hypothesis.

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