Ascertainment of premature mortality, life expectancy, and
biological aging
Death information and date of death were confirmed by reference to the
death certificates held by the National Health Service Information
Centre for participants in England and Wales and the National Health
Service Central Register Scotland for participants from Scotland. The
participants were defined as premature mortality if their deaths
occurred at ages younger than 75[28]. We
calculated the follow up person-years at risk of observation from the
date of consenting to join assessment center until the date of loss to
follow-up, the date of death, or March 1, 2021, whichever came first.
Causes of death were determined by using the International
Classification of Diseases Tenth Revision (ICD-10) codes, and its
detailed information was described in the Supplementary material.
We used the latest Office for National Statistics life tables rom age 40
to age 100 years to calculate the life expectancy of participants with
the distinct number of live births[29,30]. The
detailed methods used for estimating the difference in the life
expectancy was described in the Supplementary material.
Biological aging was measured from different perspectives, including
frailty index (FI), ΔKDM-biological age and
Homeostatic disorder (HD). The FI,
Δbiological age and HD were previously constructed and validated in the
UK Biobank[31]. For each person, FI is calculated
as the proportion of health attributes that a person has in a deficit
state. FI scores range from 0 (indicating no health deficits) to 1
(indicating every health deficit that was assessed). ΔBiological age
represented the value of biological age minus chronological age,
representing premature aging[32]. HD represents
the degree of variability in individual physiological functions and
health parameters, and the HD values are positively correlated with
biological aging. Detailed calculations of FI, ΔKDM-biological age and
HD are provided in Supplementary material.