The impact of the mortality of international migrants on estimates and comparisons of national life expectancy: A comparative study of four Nordic nations
preprintposted on 10.06.2021, 15:33 by Matthew Wallace, Michael J. Thomas, José Manuel Aburto, Anna Vera Jørring Pallesen, Laust Hvas Mortensen, Astri Syse, Sven Drefahl
Period life expectancy at birth (PLE0) is defined as how long – on average – a newborn baby could expect to live if current mortality rates do not change. It is one of the most widely used population health indicators in the world by academics, governments, statistical agencies, and international organisations. Yet, while estimates of PLE0 routinely factor immigrations and emigrations into population denominators and migrant residents form part of these population denominators, the effect of the unique mortality of international migrants on national PLE0 has almost never been studied. Here, our aim is to understand whether estimates and comparisons of national PLE0 in four Nordic nations – Denmark, Finland, Norway, and Sweden – are being affected by the mortality of their international migrant populations. We use register data for over three decades, from 1990 to 2019. We calculate PLE0 by sex for entire resident, native-born, and migrant populations, as well as the differences between them. Our analysis reveals a dynamic and increasing impact of the mortality of international migrants on national PLE0 that is already beginning to affect inter-country comparisons and rankings of mortality. Our unique findings should resonate strongly in all nations with substantial shares of international migrants and all of the aforementioned stakeholders that use PLE0 to drive and inform public health policy.