Biodemography of Human Longevity: New Methodological Approaches

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Biodemography of Human Longevity New
Methodological Approaches

• Dr. Leonid A. Gavrilov, Ph.D.
• Dr. Natalia S. Gavrilova, Ph.D.
• Center on Aging
• NORC and The University of Chicago
• Chicago, Illinois, USA

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General Approach

• To study success stories in long-term avoidance
  of fatal diseases (survival to 100 years) and
  factors correlated with this remarkable survival
  success

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Centenarians represent the fastest growing age
group in the industrialized countries

• Yet, factors predicting exceptional longevity and
  its time trends remain to be fully understood
• In this study we explored the new opportunities
  provided by the ongoing revolution in information
  technology, computer science and Internet
  expansion to explore early-childhood predictors
  of exceptional longevity

Jeanne Calment (1875-1997)
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Revolution in Information TechnologyWhat does
it mean for longevity studies?

• Over 75 millions of computerized genealogical
  records are available online now!

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Online Data Resources Used in These Studies

• Computerized genealogies
• Early U.S. censuses (1900, 1910, etc.)
• IPUMS (Integrated Public Use Microdata Series)
  1 censuses
• Social Security Administration Death Master File
• WWI civil draft registration cards

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Approach 1Using computerized genealogies
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Computerized genealogies is a promising source of
information about potential predictors of
exceptional longevity life-course events,
early-life conditions and family history of
longevity
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Computerized Genealogies as a Resource for
Longevity Studies

• Pros provide important information about family
  and life-course events, which otherwise is
  difficult to collect (including information about
  lifespan of parents and other relatives)
• Cons Uncertain data quality
  Uncertain validity and generalizability
  

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For longevity studies the genealogies with
detailed birth dates and death dates for
long-lived individuals (centenarians) and their
relatives are of particular interest

• In this study 1,001 genealogy records for
  centenarians born in 1875-1899 were collected and
  used for further age validation

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Internet Resources Used in Centenarian Age
Verification

• Social Security Administration Death Master File
  is publicly available at the Rootsweb website
  http//ssdi.rootsweb.com/cgi-bin/ssdi.cgi
• Head of household indexes and census page images
  for 1900, 1920 and 1910 federal censuses are
  provided by Genealogy.com
• Individual indexes of enumerated persons by 1900,
  1920 and 1930 federal censuses and census page
  images are provided by Ancestry.com

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Steps of Centenarian Age Verification

1. Internal consistency checks of dates
2. Verification of death dates linkage to the
   Social Security Administration Death Master File
   (DMF)
3. Verification of birth dates linkage to early
   Federal censuses (1900, 1910, 1920, 1930)

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A typical image of centenarian family in 1900
census
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Results of Centenarian Age Verification
1001 records consistency checks 990 records used for further verification
990 records were linked to the SSA Death Master File Linkage success rate 77 (80 for centenarians born after 1890) In 3 of cases centenarian status was not confirmed
548 records found in DMF for persons born in 1890-1899 were then linked to early US censuses Linkage success rate 80 when using Genealogy.com and 91 after supplementation with Ancestry.com. In 8 of cases a 1-year difference between genealogy and census record was observed for birth year
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Conclusions of the Age Verification Study

• Death dates of centenarians recorded in
  genealogies always require verification because
  of strong outliers (10-20 years difference, 1.3,
  misprints)
• Birth dates of centenarians recorded in
  genealogies are sufficiently accurate - 92 are
  correct for the remaining 8 only one-year
  disagreements
• Quality of genealogical data is good enough if
  these data are pre-selected for high data quality

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Study 1Compare centenarians found in
computerized genealogies with general population
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Case-Control Study of Early-Life Conditions and
Exceptional Longevity
Cases - 382 white households where
centenarians (born in 1890-1899) were raised
(from centenarian records linked to 1900
census) Controls 1 random sample of white
households with children below age 10 enumerated
by 1900 census (from Integrated Public Use
Microdata Sample, IPUMS http//www.ipums.umn.edu/
usa/index.html)
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Statistical Approach

• Logistic regression
• Dependent variable Households with child-future
  centenarian (y1) vs control households (y0)
• Predictor variables childhood residence,
  household property status, paternal immigration
  status, etc.

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Childhood Residence and Survival to Age 100Odds
for household to be in a centenarian group

• A New England and Middle Atlantic (reference
  group)
• B Mountain West and Pacific West
• C Southeast and Southwest
• D North Central

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Household Property Status During Childhood and
Survival to Age 100 Odds for household to be in
a centenarian group

• A Rented House
• B Owned House
• C Rented Farm
• D Owned farm
• (reference group)

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Paternal Immigration Status and Survival to Age
100 Odds for household to be in a centenarian
group

• A Father immigrated
• B Father native-born
• (reference group)

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No Association was Found (so far) Between Chances
to Become a Centenarian and

• Paternal literacy
• Child mortality of siblings

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Limitations

• Reporting bias in genealogies
• People mentioned in genealogies may be not
  representative to the whole population
• more fertile, longer-living (?), wealthier (?),
  more educated (?)

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Study 2Compare centenarians with their
siblings (between-family study)
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Birth Order and Chances to Become a Centenarian
Cases - 436 centenarians born in the United
States between 1890 and 1899 Controls their
siblings born in the same time window (1,119
controls) Model log(longevity odds ratio) ax
bx2 cz d where x birth order z family
size a,b,c,d parameters of polynomial
regression model
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Birth Order and Survival to 100
Source Gavrilova, N.S., Gavrilov, L.A. Search
for Predictors of Exceptional Human Longevity.
In Living to 100 and Beyond Monograph. The
Society of Actuaries, Schaumburg, Illinois, USA,
2005, pp. 1-49.
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Study 3Compare centenarians with their
siblings (within-family study)
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Within-Family Study of Exceptional Longevity
Cases - 198 Centenarians born in U.S. in
1890-1893 Controls Their own siblings Method
Conditional logistic regression Advantage
Allows researchers to eliminate confounding
effects of between-family variation
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Design of the Study
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First-born siblings are more likely to become
centenarians (odds 1.8)
Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
First-born status 1.77 1.18-2.66 0.006
Male sex 0.40 0.28-0.58 lt0.001
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Birth Order and Odds to Become a Centenarian
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Can the birth-order effect be a result of
selective child mortality, thus not applicable to
adults?

• Approach
• To compare centenarians with those siblings only
  who survived to adulthood (age 20)

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First-born adult siblings (20years) are more
likely to become centenarians (odds
1.95)
Conditional (fixed-effects) logistic regression N797, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N797, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N797, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N797, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
First-born status 1.95 1.26-3.01 0.003
Male sex 0.46 0.32-0.66 lt0.001
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Are young fathers responsible for birth order
effect?
Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
Born to young father 1.86 0.99-3.50 0.056
Male sex 0.42 0.29-0.59 lt0.001
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Birth order is more important than paternal age
for chances to become a centenarian
Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
First-born status 1.64 1.03-2.61 0.039
Born to young father 1.29 0.63-2.67 0.484
Male sex 0.41 0.29-0.58 lt0.001
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Are young mothers responsible for the birth order
effect?
Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
Born to young mother 2.03 1.33-3.11 0.001
Male sex 0.41 0.29-0.59 lt0.001
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Maternal Age at Persons Birth and Odds to Become
a Centenarian
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Birth order effect explainedBeing born to young
mother!
Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N950, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
First-born status 1.36 0.86-2.15 0.189
Born to young mother 1.76 1.09-2.85 0.021
Male sex 0.41 0.29-0.58 lt0.001
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Even at age 75 it still helps to be born to young
mother (age lt25)(odds 1.9)
Conditional (fixed-effects) logistic regression N557, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N557, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N557, Prob gt chi20.0000 Conditional (fixed-effects) logistic regression N557, Prob gt chi20.0000
Variable Odds ratio 95 CI P-value
Born to young mother 1.86 1.15-3.05 0.012
Male sex 0.46 0.31-0.69 lt0.001
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Conclusions

• Centenarians are more likely to be first-born
• The effect of first-born status is driven mostly
  by young maternal age (lt25) at persons birth
• Being born to young mother is an important
  predictor of human longevity even at age 75

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Approach 2Using Social Security Administration
Death Master File
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What Is SSA DMF ?

• SSA DMF is a publicly available data resource
  (available at Rootsweb.com)
• Covers 93-96 percent deaths of persons 65
  occurred in the United States in the period
  1937-2003
• Some birth cohorts covered by DMF could be
  studied by method of extinct generations
• Considered superior in data quality compared to
  vital statistics records by some researchers

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Month-of-Birth and Mortality at Advanced Ages

• SSA Death Master File allows researchers to study
  mortality in real birth cohorts by month-of-birth
• Provides more accurate and unbiased estimates of
  life expectancy by month of birth compared to
  usage of cross-sectional death certificates

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Month of Birth Predicts the US Life Expectancy at
Age 80 Computed using the Social Security
Administration data
Source Gavrilova, N.S., Gavrilov, L.A. Search
for Predictors of Exceptional Human Longevity.
In Living to 100 and Beyond Monograph. The
Society of Actuaries, Schaumburg, Illinois, USA,
2005, pp. 1-49.
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Seasonality (month-of-birth effects) for
US life expectancy
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Approach 3Using Civil Draft Registration Cards
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Physical Characteristics at Young Age and
Survival to 100
A study of height and build of centenarians when
they were young using WWI civil draft
registration cards
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WWI Civilian Draft Registration

• In 1917 and 1918, approximately 24 million
  men born between 1873 and 1900 completed draft
  registration cards. President Wilson proposed the
  American draft and characterized it as necessary
  to make "shirkers" play their part in the war.
  This argument won over key swing votes in
  Congress.

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Information Available in the Draft Registration
Card

• age, date of birth, race, citizenship
• permanent home address
• occupation, employer's name
• height (3 categories), build (3 categories), eye
  color, hair color, disability

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Draft Registration CardAn Example

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Data Sources

1. Social Security Administration Death Master File
2. WWI civil draft registration cards (completed for
   almost 100 percent men born between 1873 and
   1900)

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Study Design

• Cases men centenarians born in 1887 (randomly
  selected from the SSA Death Master File) and
  linked to the WWI civil draft records. Out of
  120 selected men, 19 were not eligible for draft.
  The linkage success for remaining 101 records was
  75 (76 records)
• Controls men matched on birth year, race and
  county of WWI civil draft registration

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Height and Survival to 100
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Body Build and Survival to 100
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Results of multivariate study
Variable OR P-value
Tall and medium height vs short height 1.98 0.308
Slender and medium build vs stout build 9.96 0.032
Qualified jobs vs unqualified 1.57 0.300
Married vs unmarried 1.02 0.958
Natural born vs immigr. 1.12 0.782
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Conclusion

• The study of height and build among men born in
  1887 suggests that rapid growth and overweight at
  young adult age (30 years) might be harmful for
  attaining longevity

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General Conclusion

• The shortest conclusion was suggested in the
  title of the New York Times article about our
  previous related study

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Acknowledgments

• This study was made possible thanks to
• generous support from the National Institute on
  Aging and the Society of Actuaries

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