Predictors of Exceptional Longevity Dr. Leonid A. Gavrilov, Ph.D. Dr. Natalia S. Gavrilova, Ph.D. Center on Aging NORC and The University of Chicago Chicago, Illinois, USA
Mortality at Advanced Ages Source:Gavrilov L.A., Gavrilova N.S. The Biology of Life Span: A Quantitative Approach, NY: Harwood Academic Publisher, 1991
Invertebrates: Nematodes, shrimps, bdelloid rotifers, degenerate medusae (Economos, 1979) Drosophila melanogaster (Economos, 1979; Curtsinger et al., 1992) Medfly (Carey et al., 1992) Housefly, blowfly (Gavrilov, 1980) Fruit flies, parasitoid wasp (Vaupel et al., 1998) Bruchid beetle (Tatar et al., 1993) Mammals: Mice (Lindop, 1961; Sacher, 1966; Economos, 1979) Rats (Sacher, 1966) Horse, Sheep, Guinea pig (Economos, 1979; 1980) However no mortality deceleration is reported for Rodents (Austad, 2001) Baboons (Bronikowski et al., 2002) Mortality Deceleration in Other Species
Mortality Leveling-Off in House FlyMusca domestica Our analysis of the life table for 4,650 male house flies published by Rockstein & Lieberman, 1959. Source: Gavrilov & Gavrilova. Handbook of the Biology of Aging, Academic Press, 2006, pp.3-42.
Existing Explanations of Mortality Deceleration • Population Heterogeneity (Beard, 1959; Sacher, 1966). “… sub-populations with the higher injury levels die out more rapidly, resulting in progressive selection for vigour in the surviving populations” (Sacher, 1966) • Exhaustion of organism’s redundancy (reserves) at extremely old ages so that every random hit results in death (Gavrilov, Gavrilova, 1991; 2001) • Lower risks of death for older people due to less risky behavior (Greenwood, Irwin, 1939) • Evolutionary explanations (Mueller, Rose, 1996; Charlesworth, 2001)
Problems in Hazard Rate Estimation At Extremely Old Ages • Mortality deceleration in humans may be an artifact of mixing different birth cohorts with different mortality (heterogeneity effect) • Standard assumptions of hazard rate estimates may be invalid when risk of death is extremely high • Ages of very old people may be highly exaggerated
Social Security Administration Death Master File Helps to Alleviate the First Two Problems • Allows to study mortality in large, more homogeneous single-year or even single-month birth cohorts • Allows to study mortality in one-month age intervals narrowing interval of hazard rates estimation
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 1937-2009 • 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
Social Security Administration Death Master File (DMF) Was Used in This Study: (1) Study of cohort mortality at advanced ages: Estimation of hazard rates for each month of age for single-year extinct birth cohorts. (2) Month-of-birth and mortality after age 80: Estimation of life expectancy in real birth cohort according to month of birth.
Hypothesis Mortality deceleration at advanced ages should be less expressed for data of higher quality
Quality Control (1) Study of mortality in states with different quality of age reporting: Records for persons applied to SSN in the Southern states, Hawaii and Puerto Rico were suggested to have lower quality (Rosenwaike, Stone, 2003)
Quality Control (2) Study of mortality for earlier and later single-year extinct birth cohorts: Records for later born persons were suggested to have higher quality due to more accurate age reporting.
Mortality at advanced ages: Actuarial 1900 cohort life table and SSDI 1887 cohort Source for actuarial life table: Bell, F.C., Miller, M.L. Life Tables for the United States Social Security Area 1900-2100 Actuarial Study No. 116
Mortality at advanced ages: Actuarial cohort life table and SSDI 1887 cohortEstimating Gompertz slope parameter 1900 cohort, age interval 50-100 alpha (95% CI): 0.092 (0.092,0.093) 1887 cohort, age interval 85-103 alpha (95% CI): 0.094 (0.093,0.095) 1887 cohort, age interval 85-100 alpha (95% CI): 0.117 (0.116,0.118)
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
Conclusions • Late-life mortality deceleration appears to be not that strong - cohort mortality at advanced ages continues to grow up to age 105 years • Month of birth effects on mortality exist at age 80 but then fade and disappear by age 100+
Data Sources Social Security Administration Death Master File WWI civil draft registration cards (completed for almost 100 percent men born between 1873 and 1900)
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.
WWI Draft Registration Registration was done in three parts, each designed to form a pool of men for three different military draft lotteries. During each registration, church bells, horns, or other noise makers sounded to signal the 7:00 or 7:30 opening of registration, while businesses, schools, and saloons closed to accommodate the event.
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
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 240 selected men, 15 were not eligible for draft. The linkage success for remaining records was 77.5% (174 records) Controls: men matched on birth year, race and county of WWI civil draft registration
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
Height – What to Expect Height seems to be a good indicator of nutritional status and infectious disease history in the past. Historical studies showed a negative correlation between height and mortality. Hence we may expect that centenarians were taller than average
Build – What to Expect Slender build may suggest a poor nutrition during childhood. We may expect that centenarians were less likely to be slender when young. On the other hand, biological studies suggest that rapid growth may be harmful and somewhat delayed maturation may be beneficial for longevity.