White Blood Cell Count and Mortality in the Baltimore Longitudinal Study of Aging
Carmelinda Ruggiero, MD*, ,*,
E. Jeffrey Metter, MD*,
Antonio Cherubini, MD, PhD,
Marcello Maggio, MD, PhD*,
Ranjan Sen, MD, PhD ,
Samer S. Najjar, MD ,
Gwen B. Windham, MD*,
Alessandro Ble, MD*,
Umberto Senin, MD and
Luigi Ferrucci, MD, PhD*
* Longitudinal Studies Section, Clinical Research Branch, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
Laboratory of Cellular and Molecular Biology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
Human Cardiovascular Studies Unit, Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
Department of Geriatrics and Gerontology, University of Perugia, Perugia, Italy.
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Figure 1 Longitudinal Changes in WBC Count by Years of Initial Evaluation, Separately in Men and Women
The upward trend of white blood cell (WBC) count in the oldest cohorts can be explained by participants enrolled in the first 2 enrollment periods, who developed an increase in WBC count in their very old age. Numbers in the table are for participants enrolled in different time periods and, of these, the number who were still alive at the beginning of each decade.
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Figure 2 Relationship Between Excess Mortality and WBC Count in the Entire BLSA Trial Sample
The absolute difference between the observed mortality hazard and the expected mortality hazard over time is expressed as excess mortality and plotted against white blood cell (WBC) count for the entire sample. The dashed lines represent the 95% confidence intervals.
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Figure 3 Kaplan-Meier Survival Curves and Proportional Hazard Survival Plots According to WBC Count Groups
(A) Kaplan-Meier curves. (B) Proportional hazard survival plots were evaluated at mean values of the explanatory variables. In participants with white blood cell (WBC) count  3,500/mm3, the predicted survival was extrapolated up to 20 years of follow-up, because of the absence of events after 20 years.
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Figure 4 Longitudinal Changes in WBC, Neutrophil, and Lymphocyte Counts
Longitudinal changes of age- and date-adjusted (A) white blood cell (WBC), (B) neutrophil, and (C) lymphocyte counts observed in the BLSA participants according to time before death for participants who died during the follow-up, and time before censorship for those who were censored. Note that neutrophils and lymphocytes are limited to participants who had differential WBC count (n = 6,227). 95% confidence interval estimated by a bootstrapping method.
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