Potential and challenges for sustainable progress in human longevity.

Between 1992 and 2005, gains in life expectancy were both substantial and widespread across subnational regions of Western Europe, with laggard regions experiencing the fastest improvements.

• The study examined subnational mortality trends across N=450 regions in Western Europe.
• The study period covered 1992 to 2019, with the first sub-period being 1992–2005.
• Laggard regions experienced the fastest improvements during 1992–2005.
• The rapid improvement in laggard regions yielded rapid regional convergence during this period.

Between 2005 and 2019, gains in life expectancy decelerated in laggard regions while remaining remarkably stable in vanguard regions.

• The second sub-period examined was 2005–2019.
• Vanguard regions maintained stable life expectancy gains during 2005–2019, suggesting continued extension of longevity remains possible.
• Laggard regions, which had previously shown the fastest improvements, experienced a notable slowdown in gains.
• The divergence between vanguard and laggard regions emerged as a key feature of the later period.

The observed slowing of life expectancy gains is strongly associated with mortality at ages 55–74, which increased across large areas of Western Europe between 2005 and 2019.

• Mortality increases at ages 55–74 were particularly prominent in Germany and France.
• The association between decelerated e0 gains and mortality at ages 55–74 was strong.
• The increase in mortality at these ages occurred across 'large areas of Western Europe.'
• This age group (55–74) was identified as a critical driver of the overall deceleration in life expectancy progress.

Subnational analysis of mortality trends is crucial for revealing both the potential for and challenges to sustainable progress in human longevity.

• The study used N=450 subnational regions in Western Europe.
• National-level analyses would obscure the divergence between vanguard and laggard regions identified in this study.
• Fine geographical monitoring revealed that some regions continued to make progress even as overall national gains decelerated.
• The authors conclude that subnational monitoring is essential for understanding the heterogeneity of longevity trends.

Decelerating gains in life expectancy in high-income countries have raised concerns about the future of human longevity, motivating this subnational investigation.

• The study was motivated by concerns about decelerating e0 gains observed in high-income countries.
• The analysis covers Western Europe over the period 1992–2019.
• The study uses subnational data (N=450 regions) to enhance understanding of these developments.
• The approach contrasts with prior work focused primarily at the national level.