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Biodemography of Human Longevity: New Methodological Approaches

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. General Approach.

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Biodemography of Human Longevity: New Methodological Approaches

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  1. 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

  2. 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

  3. 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)

  4. Revolution in Information TechnologyWhat does it mean for longevity studies? Over 75 millions of computerized genealogical records are available onlinenow!

  5. 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

  6. Approach 1:Using computerized genealogies

  7. 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

  8. 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

  9. 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

  10. 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

  11. Steps of Centenarian Age Verification • Internal consistency checks of dates • Verification of death dates – linkage to the Social Security Administration Death Master File (DMF) • Verification of birth dates – linkage to early Federal censuses (1900, 1910, 1920, 1930)

  12. A typical image of ‘centenarian’ family in 1900 census

  13. Results of Centenarian Age Verification

  14. 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

  15. Study 1:Compare centenarians found in computerized genealogies with general population

  16. 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 10enumerated by 1900 census (from Integrated Public Use Microdata Sample, IPUMS: http://www.ipums.umn.edu/usa/index.html)

  17. Statistical Approach: Logistic regression Dependent variable: Households with child-future centenarian (y=1) vs control households (y=0) Predictor variables: childhood residence, household property status, paternal immigration status, etc.

  18. 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

  19. Household Property Status During Childhood and Survival to Age 100Odds for household to be in a ‘centenarian’ group A – Rented House B – Owned House C – Rented Farm D – Owned farm (reference group)

  20. Paternal Immigration Status and Survival to Age 100Odds for household to be in a ‘centenarian’ group A – Father immigrated B – Father native-born (reference group)

  21. No Association was Found (so far) Between Chances to Become a Centenarian and • Paternal literacy • Child mortality of siblings

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

  23. Study 2:Compare centenarians with their siblings (between-family study)

  24. 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

  25. 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.

  26. Study 3:Compare centenarians with their siblings (within-family study)

  27. 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

  28. Design of the Study

  29. First-born siblings are more likely to become centenarians (odds = 1.8)

  30. Birth Order and Odds to Become a Centenarian

  31. 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)

  32. First-born adult siblings (20+years) are more likely to become centenarians (odds = 1.95)

  33. Are young fathers responsible for birth order effect?

  34. Birth order is more important than paternal age for chances to become a centenarian

  35. Are young mothers responsible for the birth order effect?

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

  37. Birth order effect explained:Being born to young mother!

  38. Even at age 75 it still helps to be born to young mother (age <25)(odds = 1.9)

  39. Conclusions • Centenarians are more likely to be first-born • The effect of first-born status is driven mostly by young maternal age (<25) at person’s birth • Being born to young mother is an important predictor of human longevity even at age 75

  40. Approach 2:Using Social Security Administration Death Master File

  41. 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

  42. 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

  43. 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.

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

  45. Approach 3:Using Civil Draft Registration Cards

  46. 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

  47. 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.

  48. 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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