Abstract Background The poor performance of the UK in reducing mortality compared to many other high-income countries following the 2008 financial crisis have been extensively studied, with particular attention to deaths of despair at working ages. However, longer-term trends in the differences in working-age mortality between the UK and peer countries have not been systematically investigated. Methods We compared trends (1990–2019) in age-standardised mortality rates at age 25–49 years in the UK and its constituent parts (England and its 9 standard regions, Wales, Scotland, Northern Ireland) with those of 21 peer countries. Findings Between 1990 and 2019 the UK went from having relatively low mortality rates at age 25–49 years compared to its peers to having one of the highest. This reflects both the better progress made by many other countries in reducing mortality rates as well as an absolute increase in the UK from 2013. Against the counter-factual that rates in the UK followed the median of the comparator countries (2001–2019) this resulted in 3.1 million excess years of life lost. The divergence in mortality of the UK with its peers was apparent from 1990 and was observed for all constituent parts of the UK and English regions. External cause mortality accounted for much of the divergence in rates between 2001 and 2019 (69% women; 78% men), as did the overlapping categories of drug-related deaths (42%; 28%) and suicides (17%; 20%). Alcohol-related deaths made only a small contribution. Interpretation The divergence in mortality rates at ages 25–49 years in the UK from peer countries was already apparent from 1990, pre-dating the austerity policies two decades later. Nevertheless, austerity may well have exacerbated this longer-term deterioration in the UKs position. The fact that all areas of the UK showed deterioration relative to peer countries indicates that this is a national problem.
Leon et al. (2026) studied this question.