factors of exceptional longevity dr. natalia s. gavrilova, ph.d. dr. leonid a. gavrilov, ph.d....

Factors of Exceptional Longevity

Dr. Natalia S. Gavrilova, Ph.D.Dr. Leonid A. Gavrilov, Ph.D.

Center on Aging

NORC and The University of Chicago Chicago, Illinois, USA

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

Sarah Knauss (1880-1999)Pennsylvania, USA

Revolution in Information Technology

What does it mean for longevity studies?

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

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

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

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

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

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)

A typical image of ‘centenarian’ family in 1900

census

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 disagreement between genealogy and census record was observed

Conclusions of the Age Verification Study

Death dates of centenarians recorded in genealogies always require verification because of strong outliers (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

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 + dwhere x – birth order; z – family size; a,b,c,d – parameters of polynomial regression model

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.

Birth order

1 2 3 4 5 6 7 8 9 10

Od

ds

to b

eco

me

a ce

nte

nar

ian

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

FemalesMales

New Developments

Can birth order effect be confirmed by more rigorous approach – a strictly within-family analysis?

Method of conditional logistic regression allows us to compare centenarians with their siblings within the same family. This eliminates confounding caused by between-family variation.

First-born siblings are more likely to become centenarians

(odds = 1.8) Conditional (fixed-effects) logistic regression Number of obs = 950 LR chi2(2) = 33.75 Prob > chi2 = 0.0000Log likelihood = -282.22348 Pseudo R2 = 0.0564

---------------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+--------------------------------------------------------

First-born status 1.772 0.006 1.180 2.663

Male sex .404 0.000 .284 .576---------------------------------------------------------------------------------

Birth Order and Odds to Become a Centenarian

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)

First-born adult siblings (20+years) are more likely to

become centenarians (odds = 1.95)

Conditional (fixed-effects) logistic regression Number of obs = 797 LR chi2(2) = 27.54 Prob > chi2 = 0.0000Log likelihood = -247.93753 Pseudo R2 = 0.0526

---------------------------------------------------------------------------------- Variable | Odds Ratio P>|z| [95% Conf. Interval]-------------+--------------------------------------------------------------------

First-born status | 1.949 0.003 1.261 3.010

Male sex | .458 0.000 .318 .658

----------------------------------------------------------------------------------

Even at age 75 it still helps to be a first-born child

(odds = 1.7) Conditional (fixed-effects) logistic regression Number of obs = 557 LR chi2(2) = 19.03 Prob > chi2 = 0.0001Log likelihood = -186.22869 Pseudo R2 = 0.0486

---------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+--------------------------------------------------

First-born status 1.659 0.040 1.022 2.693

Male sex .459 0.000 .306 .687

----------------------------------------------------------------

Are young fathers responsible for birth order effect?

Conditional (fixed-effects) logistic regression Number of obs = 950 LR chi2(2) = 30.11 Prob > chi2 = 0.0000Log likelihood = -284.04284 Pseudo R2 = 0.0503

--------------------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+-------------------------------------------------------------

Born to young father 1.856 0.056 .985 3.496

Male sex .415 0.000 .291 .590

---------------------------------------------------------------------------

Birth order is more important than paternal age for chances

to become a centenarianConditional (fixed-effects) logistic regression Number of obs = 950 LR chi2(3) = 34.24 Prob > chi2 = 0.0000Log likelihood = -281.97993 Pseudo R2 = 0.0572

---------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+--------------------------------------------------

First-born status 1.635 0.039 1.025 2.607

Born to young father 1.294 0.484 .628 2.668

Male sex .407 0.000 .285 .580

--------------------------------------------------------------------------------------

Are young mothers responsible for the birth order

effect?Conditional (fixed-effects) logistic regression Number of obs = 950 LR chi2(2) = 37.35 Prob > chi2 = 0.0000Log likelihood = -280.42473 Pseudo R2 = 0.0624

------------------------------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+-----------------------------------------------------------------------

Born to young mother 2.031 0.001 1.326 3.110

Male sex .412 0.000 .289 .586

-------------------------------------------------------------------------------------

Maternal Age at Person’s Birth and Odds to Become a

Centenarian

Birth order effect explained:Being born to young

mother!Conditional (fixed-effects) logistic regression Number of obs = 950 LR chi2(3) = 39.05 Prob > chi2 = 0.0000Log likelihood = -279.57165 Pseudo R2 = 0.0653

------------------------------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+-----------------------------------------------------------------------

First-born status 1.360 0.189 .859 2.153

Born to young mother 1.760 0.021 1.089 2.846

Male sex .407 0.000 .285 .580

--------------------------------------------------------------------------------------

Even at age 75 it still helps to be born to young mother (age

<25)(odds = 1.9)

Conditional (fixed-effects) logistic regression Number of obs = 557 LR chi2(2) = 21.31 Prob > chi2 = 0.0000Log likelihood = -185.08639 Pseudo R2 = 0.0544

---------------------------------------------------------------------------------- Variable Odds Ratio P>|z| [95% Conf. Interval]-------------+--------------------------------------------------------------------

Born to young mother 1.869 0.012 1.145 3.051

Male sex .461 0.000 .307 .690

----------------------------------------------------------------------------------

Younger Moms' Kids Get Longevity Edge

Children of women under 25 twice as likely to live to 100, study finds

HealthDayMonday, April 17, 2006

MONDAY, April 17 (HealthDay News) -- Society's oldest members are most likely to be born to its youngest mothers, new research suggests.

The odds of living to 100 and beyond double when a person is born to a woman under 25 years of age, compared to those people born to older mothers, according to one of the most rigorous studies on the subject yet conducted.

The finding may also help clear up a statistical mystery -- three years ago, the same husband-and-wife team of researchers found that being the first-born child in a family also boosted longevity, although no one knew why.

Being born to Young Mother Helps Laboratory Mice to Live

Longer

Source:

Tarin et al., Delayed Motherhood Decreases Life Expectancy of Mouse Offspring.

Biology of Reproduction 2005 72: 1336-1343.

Back to a broader comparison of

‘centenarian’ and ‘non-centenarian’ families

Case-Control Study of Early-Life Conditions and Exceptional

LongevityCases - 382 households where centenarians (born in 1890-1899) were raised (from centenarian records linked to 1900 census)

Controls – 1% random sample of 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)

Childhood Residence and Survival to Age 100

Odds 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 Central0

0.5

1

1.5

2

2.5

3

3.5

A B C D

MalesFemales

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)

00.10.20.30.40.50.60.70.80.9

1

A B C D

MalesFemales

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)

00.10.20.30.4

0.50.60.70.80.9

1

A B

MalesFemales

No Association was Found (so far) Between Chances to

Become a Centenarian and

Paternal literacy

Child mortality of siblings

Month of Birth

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

life

exp

ecta

ncy

at

age

80, y

ears

7.6

7.7

7.8

7.9

1885 Birth Cohort1891 Birth Cohort

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.

Seasonality (month-of-birth effects) for US life expectancy

Within-Family Study of Month-of-Birth Effects on Exceptional

Longevity

Cases - Centenarians born in 1890-1893

Controls – Their own siblings

Method: Conditional logistic regression

Advantage: Allows researchers to eliminate confounding effects of between-family variation

Month of Birth and the Likelihood to Become a Centenarian

Method:

Conditional logistic regression for odds to become a centenarian, using siblings as within-family control.

921 observations

Month of Birth and the Likelihood to Become a Centenarian

for Adult Siblings (20+ years)

Method:

Conditional logistic regression for odds to become a centenarian, using siblings as within-family control.

787 observations

Conclusions

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

Conclusions

The chances of exceptional longevity are strongly modulated by such characteristics of person's childhood as:

Mother's age at person's birth Month of birth Place of birth and some other characteristics

of parental family

Most important, these findings indicate that a larger research project on early-life determinants of exceptional human longevity is likely to produce more new results, very important for future longevity studies

AcknowledgmentsThis study was made possible thanks to:

generous support from the National Institute on Aging and

the Society of Actuaries

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