BMI and mortality in the aged

From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Wed Aug 25 1999 - 06:02:54 MDT


Chubby old people seem to do well in the longevity sweapstakes.
This seems to fit in with other research which associates risk factors
such as low cardioresipratory fitness, and high blood pressure as being
responsible for higher mortality in young people at either end of the BMI
scale. These would tend to die early, yielding mostly survivors that are
relatively healthy regardless of BMI.
 The "U" or "J" relation found in most studies relating human mortality
with body weight, thus tends to naturally flatten out at progressively
older ages.

 ---------- Forwarded message ----------

Authors
  Allison DB. Gallagher D. Heo M. Pi-Sunyer FX. Heymsfield SB.
Institution
  Obesity Research Center, St. Luke's/Roosevelt Hospital Center, Columbia
  University College of Physicians & Surgeons, NY 10025, USA.
Title
  Body mass index and
  all-cause mortality among people age 70 and over: the
  Longitudinal Study of Aging.
Source
  International Journal of Obesity & Related Metabolic Disorders.
  21(6):424-31, 1997 Jun.
Abstract
  OBJECTIVES: To assess the relationship between body
  mass index (BMI; kg/m2) and
  mortality in a large nationally representative sample of US
  adults over age 70 years. DESIGN: Prospective longitudinal cohort study, the
  Longitudinal Study of Aging (LSOA). Subjects were all those 7260 black and
  white people (2769 men, 4491 women) initially interviewed in 1984 for whom
  height and weight were available. These subjects were followed through to
  1990. MEASUREMENTS: Measurements included self-reported height and weight,
  date of death if subjects died, sex, age, race, measures of socio-economic
  status, number of living first degree relatives, and responses to questions
  asking whether the subject had retired due to poor health, had difficulty
  eating, worried about their health, and felt their health was worse than
  during the prior year. Smoking status was not assessed. RESULTS: When
  analyzed via Cox proportional hazard regression, the relationship between BMI
  and mortality, represented by means of hazard ratio, was
  clearly U-shaped for both men and women. The base of the curves was fairly
  wide suggesting that a broad range of BMIs are well tolerated by older
  adults. The minimum mortality (estimated from the fitted
  proportional hazard models) occurred at a BMI of approximately 31.7 for women
  and 28.8 for men. The results were essentially unchanged, if analyses were
  weighted, if various disease states were controlled for, and if apparently
  unhealthy subjects were excluded. CONCLUSIONS: The finding of the relatively
  high BMI (27-30 for men, 30-35 for women) associated with minimum hazard in
  persons older than seventy years supports some previously documented findings
  and opposes others and, if confirmed in future research, has implications for
  public health and clinical recommendations.



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