Tracing the Genetic Footprints of the UK National Health Service
Nicolau Martin-Bassols, Pietro Biroli, Elisabetta De Cao, Massimo Anelli, Stephanie von Hinke, Silvia Mendolia
TL;DR
This study assesses how the UK National Health Service (NHS) implementation in 1948 affected early-life mortality and whether survival became genetically selective. Using a regression discontinuity design around the NHS cutoff and multiple data sources (GRO vital statistics, 1951 Census SES, and genotyped cohorts UKB, ELSA, USoc), the authors document a substantial drop in infant mortality, driven by reductions in stillbirths and diarrhea-related deaths. They then examine whether the survival shift altered the genetic composition of survivors by analyzing PGIs, finding consistent evidence that post-NHS cohorts had higher PGIs for contextually adverse traits and lower PGIs for favorable traits, with effects up to about 7.5% of a standard deviation. The findings hold across datasets and persist in within-family analyses, with stronger selective survival in socioeconomically disadvantaged areas and among males, highlighting how large public policies can imprint population composition and induce long-term biases in survival and outcomes.
Abstract
The establishment of the UK National Health Service (NHS) in July 1948 was one of the most consequential health policy interventions of the twentieth century, providing universal and free access to medical care and substantially expanding maternal and infant health services. In this paper, we estimate the causal effect of the NHS introduction on early-life mortality and we test whether survival is selective. We adopt a regression discontinuity design under local randomization, comparing individuals born just before and just after July 1948. Leveraging newly digitized weekly death records, we document a significant decline in stillbirths and infant mortality following the introduction of the NHS, the latter driven primarily by reductions in deaths from congenital conditions and diarrhea. We then use polygenic indexes (PGIs), fixed at conception, to track changes in population composition, showing that cohorts born at or after the NHS introduction exhibit higher PGIs associated with contextually-adverse traits (e.g., depression, COPD, and preterm birth) and lower PGIs associated with contextually-valued traits (e.g., educational attainment, self-rated health, and pregnancy length), with effect sizes as large as 7.5% of a standard deviation. These results based on the UK Biobank data are robust to family-based designs and replicate in the English Longitudinal Study of Ageing and the UK Household Longitudinal Study. Effects are strongest in socioeconomically disadvantaged areas and among males. This novel evidence on the existence and magnitude of selective survival highlights how large-scale public policies can leave a persistent imprint on population composition and generate long-term survival biases.