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Survival to 90 Years Linked to Low Weight in Young Adulthood and Exercise: Presented at AAN

By Paula Moyer

HONOLULU, HI -- April 8, 2003 -- People who are slender in young adulthood and exercise regularly when they become elderly are more likely to survive to the age of 90 years, according to a study of close to 14,000 subjects.

"Those in the lowest tertile of body mass index [BMI] at age 21 were most likely to survive to 90," said Claudia H. Kawas, MD, professor of medicine, University of California-Irvine.

On the other hand, those in the lowest BMI tertile when elderly were least likely to live to 90 years. Dr. Kawas presented these findings here April 3^rd at the 55^th Annual Meeting of the American Academy of Neurology.

She and colleagues sought to study the association between height, weight, exercise and survival to age 90. Their rationale was that although weight, BMI, and exercise have been studied in relation to improved health and mortality, investigators know little about the relevance of these factors to survival into the tenth decade of life.

The participants were drawn from the Leisure World Cohort Study, which is a population-based prospective investigation whose participants live in a California retirement community. Between 1981 and 1985, 13,979 subjects completed an initial mailed survey. The participants responded to questions about their lifestyle and medical history.

Dr. Kawas and her investigative team conducted a logistic regression analysis to calculate the odds of dying before the age of 90. The variables used in the analysis were height, current weight, weight at the age of 21, BMI, and outdoor exercise. Height was expressed in inches; weight was expressed in pounds. The respondents were divided into low, medium, and high tertiles by BMI. Respondents characterised their daily outdoor exercise as none, less than 1 hour per day, and 1 hour or more per day.

The investigators adjusted the model for the potentially confounding effects of gender, baseline age, smoking status, and respondents' history of several medical conditions that are typically associated with decreased survival. These included hypertension, angina, myocardial infarction, stroke, diabetes, fractures, and cancer.

The investigators then estimated the odds ratios (OR) for all the variables simultaneously in one model. Because of the many concurrent estimates, defined significance as 0.001. They excluded 2,830 subjects who were alive but les than 90 years old, 185 subjects who were at least 90 years old at baseline, and 600 subjects whose information for the variables of interest was missing.

As of October 2002, 6,728 of the original participants had died before the age of 90, and 3,636 had survived to at least 90 years of age. The average age at baseline of the 10,364 participants who were analysed was 75 years old, with a range of 52 to 89 years. Their average follow-up time was 11 years; follow-up ranged from 0 to 22 years.

After adjusting for age, gender and medical histories, the researchers found that baseline height and weight were not associated with mortality. However, a higher weight at age 21 was associated with increased odds of dying before reaching 90 years (OR=1.04 per 5 lb increase, P 0.0001). Those who exercised were 24-31% less likely to die by the age of 90 (OR=0.76, P 0.0001 for less than 1 hour per day, OR=0.69, P 0.0001 for 1 hour or more per day). Similarly, being in the mid tertile of BMI at baseline (22-24 for men, 20-23 for women) was associated with decreased odds of dying before age 90 (OR=0.70, P 0.0001).


[Study title: Low Weight in Early Adulthood and Later Life Exercise Increase Chances of Surviving to Age 90. Abstract: S58.002]

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