Obesity could throw off mortality projections for members of Generation X, researchers warn.

Eric Reither, a sociologist at Utah State University in Logan, Utah, and two colleagues have published an analysis of the possible effects of obesity on mortality in Health Affairs, a health policy academic journal.

A typical “two-dimensional” analysis would take current age-specific mortality statistics for a condition such as coronary heart disease and simply apply the current death rates for today’s older individuals to population statistics for individuals in Generation X, or some other age cohort, through a linear extrapolation process, the researchers say.

“Two-dimensional projections are likely to underestimate the future prevalence and severity of morbidity because they do not account for the fact that recent cohorts are, as a rule, becoming obese at earlier ages than their predecessors,” the researchers say.

To create a “three-dimensional” projection, Reither and his colleagues used coronary heart disease death statistics, or “model coefficients,” for specific age-period cohorts from another study. The researchers used the period and cohort effect estimates to project coronary heart disease mortality for U.S. males ages 45 to 49 in 2002 and 2007.

In 2002 and 2007, the coronary heart disease death rates for the men were significantly higher than the two-dimensional approach had predicted, and the 2002 and 2007 death rates closely matched the three-dimensional projection, the researchers say.

Similarly, when the researchers created three-dimensional coronary heart disease projections for U.S. males ages 25 to 29, the three-dimension approach produced much higher – and much more accurate – mortality predictions than the two-dimensional approach produced, the researchers say.

The actual coronary heart disease death rate for men ages 25 to 29 was about 8 per 100,000 in 2007, and that was about the same as the death rate produced by the three-dimensional model, the researchers say.

The coronary heart disease death rate for men in that age group produced by the two-dimensional model was only about 5 per 100,000.

The coronary heart disease death rate for men ages 25 to 29 is now noticeably higher than it was in 1997 – and the highest it has been since about 1972.

- Allison Bell

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