'Longevity' Lecture at Duke university

Greetings,

We wonder whether some readers of  this blog work at Duke university or nearby?   We will be giving invited lecture there:

http://ipl.econ.duke.edu/seminars/node/3675

Would be glad to meet in person with those who are interested.  Feel free to e-mail us, if you like to talk to us after presentation.

Kind regards,

-- Leonid and Natalia

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-- Leonid Gavrilov, Ph.D., GSA Fellow
-- Natalia Gavrilova, Ph.D., GSA Fellow
Center on Aging, NORC at the University of Chicago
Website: http://longevity-science.org/
Blog: http://longevity-science.blogspot.com/

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Duke University Population Research Institute (DuPRI) Seminar, Thursday, September 27, 3:30 PM to 5:00 PM,  111 Social Sciences Building

New Estimates of Mortality Trajectories at Extreme Old Ages

Leonid A. Gavrilov and Natalia S. Gavrilova,  Center on Aging, NORC at the University of Chicago

Abstract

A growing number of persons living beyond age 85 underscore the need for accurate measurement and modeling of mortality at advanced ages. This is also very important issue for making correct forecasts of population aging and related demands for medical services and social support.  Earlier studies indicate that exponential growth of mortality with age (Gompertz law) is followed by a period of mortality deceleration with slower rate of growth. This study challenges earlier conclusions with new datasets and data analysis.

In this study we used U.S. cohort survival data for people born in the same calendar year.  For this purpose we obtained data from the U.S. Social Security Administration Death Master File to estimate hazard rates for 15 single-year extinct birth cohorts born in 1881-1895.   We found that mortality deceleration is far less pronounced when it is measured for shorter monthly age intervals rather than for traditional annual intervals.  To find out why does it happen we have made a simulation study and found that traditional measures of hazard rate (like the Nelson-Aalen hazard rate estimate) underestimate mortality force at extreme old ages (underestimation bias) when death rates are exceptionally high. 

We also found that mortality deceleration is far less pronounced when datasets with higher data quality (age reporting) are analyzed.  Mortality modeling found that the Gompertz model demonstrates better goodness-of-fit in age interval 88-106 years compared to logistic (Kannisto) model when used for data of good quality.  Study of mortality among other mammalian species (mice and rats) also found no mortality deceleration at advanced ages. It appears that the earlier reports of mortality deceleration for ages below 106 years may be a result of age exaggeration and the use of biased estimates of hazard rate.  This study was supported in part by the National Institute on Aging (R01 AG028620 grant). 

For more information on this study see our recent peer-reviewed article:

Gavrilov L.A., Gavrilova N.S. Mortality measurement at advanced ages: A study of the Social Security Administration Death Master File. North American Actuarial Journal, 2011, 15(3): 432-447.
Full text available at:
http://longevity-science.org/pdf/Mortality-NAAJ-2011.pdf
and
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3354762/

You can see media coverage and discussion of our new study by clicking on these titles:  Chicago Sun-Times,  Chronicle of Higher Education,  Daily Herald,  Discovery News,  Reuters,  Scripps Howard News,  U.S. News & World Report,  United Press International (UPI),  Wall Street Journal, and  Wall Street Journal Blog, or see the summary of media coverage here.

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Press Release: Mortality Grossly Underestimated at Older Ages, New Study Finds

Dear Friend and Colleagues,

Feel free to disseminate widely our News Release (please see below) on important topic of human mortality and longevity, among reporters and journalists you may know, for their coverage of new research findings.

Full text of the original peer-reviewed article is available upon your request.

Thank you, and looking forward to hear from you,

Kind regards,


-- Leonid Gavrilov, Ph.D.
Fellow of the Gerontological Society of America
Center on Aging, NORC at the University of Chicago
Website: http://longevity-science.org/
Blog: http://longevity-science.blogspot.com/

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Press Release

Longevity Chances Grossly Overestimated, New Study Finds


The chances to reach extreme old age are much lower than previously thought, new research shows

Research just published by a team of demographers at the social science research organization NORC at the University of Chicago contradicts a long-held belief that the mortality rate of Americans flattens out above age 80.

It also explains why there are only half as many people in the U.S. age 100 and above than the Census Bureau predicted there would be as recently as six years ago.

The research is based on a new way of accurately measuring mortality of Americans who are 80 years of age and older, an issue that has proven remarkably elusive in the past. The work will be significant in arriving at more accurate cost projections for programs such as Social Security and Medicare, which are based in part on mortality rates.

The research, done by Leonid A. Gavrilov and Natalia S. Gavrilova, and published in the current edition of the North American Actuarial Journal, is based on highly accurate information about the date of birth and the date of death of more than nine million Americans born between 1875 and 1895. The data is publicly available in the Social Security Administration Death Master File (SSA DMF). “It is a remarkable resource that allowed us to build what is called an extinct birth cohort that corrects or explains a number of misunderstandings about the mortality rate of our oldest citizens,” said Leonid Gavrilov.

A stark example of the problem of estimating the number of people over 100 came recently when the U.S. Census Bureau revised sharply downward the number of living centenarians. Six years ago, the bureau predicted that by 2010 there would be 114,000 people age 100 or older. The actual number turned out to be 53,364. The projection was wrong by a factor of two.

The newly published paper, titled “Mortality Measurement at Advanced Ages: A Study of the Social Security Administration Death Master File,” explains the discrepancy and is likely to make a difference in the way mortality projections for the very old are done in the future.

The key finding is straightforward—the rate of mortality growth with age of the oldest Americans is the same as that for those who are younger. The research reveals that mortality deceleration, the long-held belief that the mortality rate flattens out above age 80, does not take place.

Anne Zissu, chair of the Department of Business NYC College of Technology/CUNY, said the research provides “an essential tool” for developing models on seniors’ financial assets.

Zissu said the research “will alter our financial approach to this valuation of mortality/longevity risk. Demographers and financiers need to work on this issue together, and their models must adapt to each other.”

The mortality rate for people between the ages of 30 and 80 follows what is called the Gompertz Law, named for its founder, Benjamin Gompertz, who observed in 1825 that a person’s risk of death in a given year doubles every eight years of age. It is a phenomenon that holds up across nations and over time and is an important part of the foundation of actuarial science.

For approximately 70 years, demographers have believed that above age 80 the Gompertz Law did not hold and that mortality rates flattened out. The work done by the Gavrilovs, a husband-and-wife team, reveals that the Gompertz Law holds at least through age 106, and probably higher, but the researchers say mortality data for those older than 106 is unreliable.

The Gavrilovs say the extinct birth cohort of people born between 1875 and 1895, which they built using the Social Security Administration Death Master File, reveals beyond question that the mortality rate of people in that cohort aligns with the Gompertz Law.

“It amazes me that the Gompertz model fits so well nearly 200 years after he proposed it. I like the approach of using extinct cohorts methods on SSA DMF data by month and the use of male-female ratios to test the quality of the data at advanced ages," said Tom Edwalds, Assistant Vice President, Mortality Research, for the Munich American Reassurance Company.

Prior estimates of the number of centenarians in the United States were made in less direct ways that were subject to error. They depended, for example, on people self-reporting their age in the U.S. Census, which is less reliable than having actual birth and death data.

Gavrilov and Gavrilova work at the Center on the Economics and Demography of Aging, one of the Academic Research Centers of NORC. The study is supported by the National Institute on Aging.

The Chicago Actuarial Association (CAA) has invited the authors to present their new findings at the CAA annual meeting in Chicago on March 13.

Full text of the original peer-reviewed published study is publicly available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3269912/


About the Study Authors:

Leonid A. Gavrilov, Ph.D., is Principal Investigator of research project "Biodemography of Exceptional Longevity in the United States," awarded by 5-year grant from the National Institutes of Health, NIH. For more information, visit: http://www.norc.org/Experts/Pages/leonid-a-gavrilov.aspx . Contact e-mail: gavrilov(at)longevity-science.org

Natalia S. Gavrilova, Ph.D., is a Fellow of the Gerontological Society of America, and the author of over a hundred scientific publications. For more information, visit: http://longevity-science.org/CV-gavrilova.htm


About NORC:

NORC at the University of Chicago is an independent research organization headquartered in downtown Chicago with additional offices on the University of Chicago's campus and in the D.C. Metro area. NORC also supports a nationwide field staff as well as international research operations. With clients throughout the world, NORC collaborates with government agencies, foundations, educational institutions, nonprofit organizations, and businesses to provide data and analysis that support informed decision making in key areas including health, education, economics, crime, justice, energy, security, and the environment. NORC’s 70 years of leadership and experience in data collection, analysis, and dissemination—coupled with deep subject matter expertise—provides the foundation for effective solutions.

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News on Reliability Theory of Aging and Longevity

See also:
-- 'Books Forum' blog
-- 'Health Studies' blog


Greetings,

Here are some excerpts from the a new interview, which is just published by the scientific journal Rejuvenation Research:

Rejuvenation Research, 2009, 12(5): 371-374.
http://www.liebertonline.com/doi/abs/10.1089/rej.2009.0979
back-up copy:
http://health-studies.org/pdf/Interview-RR-2009.pdf

The excerpts are provided in their original, non-edited form, as they were initially presented before the publication.

Any comments and suggestions are welcome!

Please feel free to post your comments and suggestions below by clicking here.

-- Leonid Gavrilov

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-- Leonid Gavrilov, Ph.D. , GSA Fellow
Center on Aging, NORC/University of Chicago
Website: http://longevity-science.org/
Blog: http://longevity-science.blogspot.com/
Our books: http://longevity-science.org/Books.html

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Excerpts from Interview

Question:

3. You have spearheaded the application of reliability theory to the modeling of aging and mortality. Reliability theory is designed to describe the behavior of man-made machines, which differ from living organisms in that they do not incorporate significant in-built self-repair machinery. To what extent do you feel that this difference diminishes the applicability of reliability theory to living organisms?


Answer:

Thank you for your kind comment on our 'spearheading' . Yes, we first started to apply reliability theory to the problem of biological aging more than 30 years ago, as early as in 1978 [1, 2], and since that time the reliability theory of aging and longevity has become well known in scientific literature [3 - 9]. To answer your question on applicability of reliability theory to living organisms, it is useful to consider separately two different topics: (1) applicability of reliability theory as a general concept; and (2) applicability of our particular mathematical models based on reliability theory.

Discussing the first topic, it is important to note that reliability theory is a general theory about systems failure. It allows researchers to predict the age-related failure kinetics for a system of given architecture (reliability structure) and given reliability of its components. Although historically it was initially applied to describe the behavior of man-made machines, nothing in this general mathematical theory prevents us from taking into account the in-built self-repair machinery, if this is needed. Therefore, there are no fundamental problems with applicability of reliability theory to living organisms, as there are no problems in applicability of mathematics in general to living organisms.

Discussing the second topic, it was our initial intent to find the most simple explanation for the major facts about aging and mortality (the very origin of aging, the Gompertz law of mortality, the compensation law of mortality, and the late-life mortality deceleration). We were interested in understanding the first principles and fundamental explanations of aging, before trying to create a comprehensive model, which takes into account all the complexities of living organisms. Therefore, in our models we were focused on accumulation of un-repaired damage as the final outcome of the damage-vs-repair process, leading to age-related decrease in systems redundancy (e.g. decrease in numbers of functional cells).

Now, when these intentionally simplified models with minimum number of assumptions gave us some general understanding of the nature of aging process and mortality laws, the way is opened to build upon them a more detailed and complex model of aging. This work is opened to everyone who can find a protected time to do it.

Another interesting feature of biological systems is that they are formed in evolution during a severe struggle for survival, and biological arms race with numerous infections and predators. Therefore they have many potentially harmful defense mechanisms, which may be useful for short-term survival in hostile wild environment, but not conductive for longevity in a protected environment (like the inflammation response).

So the analogy between living organisms and man-made machines is more appropriate for a man-made military machines, overloaded by weaponry and ammunition at the expense of their durability. Such machines could last much longer in protected environment if many dangerous fighting devices are removed from them.

The same is true for living organisms -- loss of some functions through introduced mutations or other interventions often leads to increased species longevity in a protected environment. Sometimes this observation is interpreted as a proof that aging is a programmed process, while in fact it simply means that organisms were selected by Nature for survival in the wild hostile environment, rather than for longevity in protected laboratory conditions.


References

1. Gavrilov, L.A. A mathematical model of the aging of animals. Proc. Acad. Sci. USSR [Doklady Akademii Nauk SSSR], 1978, 238(2): 490-492. English translation by Plenum Publ Corp: pp.53-55. PMID 624242

2. Gavrilov, L.A., Gavrilova, N.S., Yaguzhinsky, L.S. The main regularities of animal aging and death viewed in terms of reliability theory. J. General Biology [Zhurnal Obschey Biologii], 1978, 39(5): 734-742. PMID 716614

3. Gavrilov LA, Gavrilova NS. Reliability Theory of Aging and Longevity. In: Masoro E.J. & Austad S.N.. (eds.): Handbook of the Biology of Aging, Sixth Edition. Academic Press. San Diego, CA, USA, 2006, 3-42. ISBN 0-12-088387-2

4. Gavrilov LA, Gavrilova NS. Models of Systems Failure in Aging. In: P Michael Conn (Editor): Handbook of Models for Human Aging, Burlington, MA : Elsevier Academic Press, 2006. 45-68. ISBN 0-12-369391-8.

5. Gavrilov LA, Gavrilova NS. Why We Fall Apart. Engineering's Reliability Theory Explains Human Aging. IEEE Spectrum, 2004, 41(9): 30-35.

6. Gavrilov LA, Gavrilova NS. The Reliability-Engineering Approach to the Problem of Biological Aging. Annals of the New York Academy of Sciences, 2004, 1019: 509-512. PMID 15247076

7. Gavrilov L.A., Gavrilova N.S. The quest for a general theory of aging and longevity. Science's SAGE KE (Science of Aging Knowledge Environment) for 16 July 2003; Vol. 2003, No. 28, 1-10. http://sageke.sciencemag.org , PMID 12867663

8. Gavrilov L.A., Gavrilova N.S. The reliability theory of aging and longevity. Journal of Theoretical Biology, 2001, 213(4): 527-545. PMID 11742523

9. Gavrilov L.A., Gavrilova N.S (1991), The Biology of Life Span: A Quantitative Approach. New York: Harwood Academic Publisher, ISBN 3-7186-4983-7

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Key words:
Reliability Theory of Aging and Longevity, Rejuvenation Research, Reliability Theory of Aging, Interview, Reliability Theory, , Leonid Gavrilov, Natalia Gavrilova, ageing, aging, gerontology, longevity, repair, mortality laws, the origin of aging, the Gompertz law of mortality, the compensation law of mortality, the late-life mortality deceleration


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