Research Abstract: Free Paper - Oral Presentation Australian and New Zealand Society for Geriatric Medicine Annual Scientific Meeting 2023

Aims: Estimates based on population mortality rates suggest maximum human life expectancy is around 120 years. We aimed to derive an estimate of maximum life expectancy by examining the behaviour of frailty index scores using clinical data from a representative population study.

Methods: Data were from the baseline assessments of 6,272 participants of the AHEAD cohort within the prospective US Health and Retirement Study. Frailty index scores were calculated and summarised as median values at each chronological age for each frailty quintile (1—best health; 5—poorest health) and plotted on a log scale (age vs frailty index scores with datapoints stratified by frailty quintile). Lines of best fit were extrapolated beyond the data range to show the age at which they converged for frailty quintiles 1 and 5 (hypothesised as the point of lost systemic redundancy).

Results: Participants had a mean age of 79.7 years (SD=5.7) and 62% were women. Frailty index scores were slightly higher for women (median=0.23) than for men (median=0.21). The slope of the line relating frailty index scores to age was steepest for the fittest participants (quintile 1) and least steep for the frailest participants (quintile 5). The lines converged at 124 years old (Figure). These convergence patterns were observed more strongly among women (convergence at 117 years) than among men (convergence at 149 years).

Conclusions: Maximum human life expectancy can be estimated by using frailty index dynamics to approximate ageing. This approach appears more valid in women than men.