Clinical Briefs

Life Expectancy and the 21st Century

With Comments from Russell H. Greenfield, MD

Dr. Greenfield, Medical Director, Carolinas Integrative Health Carolinas HealthCare System Charlotte, NC, Clinical Assistant Professor, School of Medicine, University of North Carolina, Chapel Hill, NC, is Executive Editor of Alternative Medicine Alert.

Source: Olshansky SJ, et al. A potential decline in life expectancy in the United States in the 21st century. N Engl J Med 2005;352:1138-1145.

Goal: To calculate the effect of current trends in obesity in the United States on life expectancy.

Design: Mathematical analysis.

Methods: The authors calculated the reduction in death rates in the United States if all Americans who currently are obese were to lose enough weight to meet criteria for having a normal body mass index, or BMI (24%). Data used for the calculations were taken from the Third National Health and Nutrition Examination Survey and the National Center for Health Statistics. Calculations included probability of death for the non-obese population and obesity-adjusted conditional probability of death.

Results: If obesity were completely eradicated, life expectancy at birth could rise by almost one year across racial and sexual categories. Should the current death rate associated with obesity remain constant, obesity would lower life expectancy by 4-9 months (more than the negative impact of all accidental deaths combined). Should trends in obesity prevalence and associated illnesses continue, the negative impact on life expectancy could increase to 2-5 years, approaching or exceeding that of cardiovascular disease or cancer.

Conclusion: Life expectancy at birth and at older ages could level off or even decline within the next few decades given the present trends in obesity. The youth of today may live less healthy and shorter lives than their parents.

Study strengths: Calculations and background data are based on firm statistics that have been repeatedly verified.

Of note: Human life expectancy has been slowly increasing over the past 1,000 years, with valleys due to infectious disease, epidemics/pandemics, famines, and war, and peaks in response to technological advances, improved living conditions, and advances in public health; most predictions of future life expectancy are based upon historical trends that do not take into account the current health status of the population; the largest increases in obesity have occurred among children and minorities, populations for whom primary medical care often is woefully inadequate; one prior study noted that obesity causes 300,000 deaths per year; the lifetime risk of diabetes for people born in the United States is now 30-40%, the mean age of onset of diabetes has decreased dramatically, and diabetes shortens lifespan by almost 13 years on average.

We knew that: Last year the Social Security Administration projected life expectancy in the United States to reach close to 85 years sometime this century, while other experts believe this estimate to be too conservative; a 2004 United Nations report predicted that in most countries of the world men and women could expect to live until age 100 years by 2300; observed trends in obesity in the United States continue to worsen, with prevalence increasing by 50% through both the 1980s and 1990s; > 60% of U.S. adults are overweight or obese, with 28% of men, 34% of women, and almost 50% of non-Hispanic black women meeting criteria for obesity; the increase in rates of obesity crosses all racial and socioeconomic strata; obesity increases the risk for numerous illnesses including diabetes, cardiovascular disease, and cancer; infection with antibiotic-resistant organisms, increased exposure to environmental pollution, and smoking could all further adversely impact future life expectancy.

Comments: This space is typically reserved for clinical trials that may impact the way we care for our patients, yet this recently published special report should spur us to action more than any single randomized controlled trial could.

The information for this review was culled directly from the article, and there are many more statistics in the piece that can leaves one’s mouth agape. There’s little need to seriously consider weaknesses in the study as the math is clear. The information contained herein serves notice to we health care professionals that the time for action is long overdue.

We must act individually and collectively on behalf of our patients (and ourselves), on both local and national levels, to ensure access to healthy fare, to promote additional physical education in schools, and to support more research into behavior modification and appropriate weight management. The political ramifications of these data are likewise profound. As the authors point out, "the U.S. population may be inadvertently saving Social Security by becoming more obese." Finally, a political stance no one could reasonably take.

What to do with this article: Make copies to hand out to your peers (and put some in the waiting room).