Long-term trends in mortality by living arrangements and the role of socioeconomic factors, Finland 1991-2020.

Recent decades have witnessed major changes in living arrangements, potentially impacting their well-established associations with mortality. However, research considering long-term trends in these differentials is scarce. We used individual-level register data on the total Finnish population aged 30 years and over from 1991 to 2020 to examine trends in the association between living arrangements and all-cause, as well as external and alcohol-related mortality. We calculated age-standardized mortality rates, quantified group differentials in absolute and relative terms, and assessed the contribution of socioeconomic factors with Poisson-models. Analyses were conducted separately for men and women in age groups 30-49, 50-69, and 70+. All-cause mortality was consistently lowest among men and women living with a partner. Highest rates were observed in the growing group of individuals living alone or with persons other than a partner or child, who experienced up to a five-fold excess mortality compared to those living with a partner and children. Mortality declined across all living arrangement groups over time. While absolute rate differences mostly narrowed, relative differences widened across all ages. Adjustments for socioeconomic factors somewhat attenuated mortality differentials, with their contribution increasing modestly by the end of the study period. In conclusion, over the past 30 years, relative mortality differences by living arrangement have increased at all ages for both men and women. These widening differentials pose a growing public health burden, particularly for the growing group of individuals living alone. Our results suggest that factors beyond socioeconomic differentiation are contributing to these trends.