Multi-morbidity and frailty at death: A new classification of death records for an ageing world.

Mortality statistics based on underlying cause of death are challenged by increased life expectancy and the growing share of population reaching ages associated with frequent multi-morbidity (with death likely resulting from interactions between multiple diseases). We provide a novel way of analysing causes of death: accounting for all causes mentioned on death certificates and summarizing this information along two dimensions emblematic of ageing populations-multi-morbidity and frailty. We implement this classification for all deaths at ages 50+ in Italy in 2014. Multi-morbid processes represent the majority of deaths, rising from 43 per cent at ages 50-54 to 63 per cent at ages 85-89. Multi-morbidity at death is more frequent among males, although age patterns are identical for both sexes. About one in four deaths involves frailty symptoms, rising to 45 per cent at ages 95+. Mortality rates involving frailty are very similar for both sexes. Supplementary material is available for this article at: https://doi.org/10.1080/00324728.2020.1820558.