Multi-Morbidity at Death and the US Disadvantage in Mortality.

The US experiences significant excess mortality compared to peer countries. The literature indicates that a similar disadvantage affects morbidity and, more generally, the prevalence of risk factors for major diseases within the US population. In this study, we assess the impact of multi-morbidity at death on the mortality gap between the US and three other high-income countries with comparable data, namely France, Italy, and Spain. The study relies on an analysis of the multiple cause-of-death information available on all death certificates for 2017, used to classify morbid processes leading to death into three categories: simple, multi-morbid, and ill-defined. The results show disproportionately high rates of multi-morbid processes in the US compared with the other three countries. Multi-morbid processes contribute 51% of the US gap in life expectancy at birth with Italy, 73% with Spain, and 75% with France, with a particular concentration at ages 20-85 years. The prevalence of multi-morbid processes in the US is consistent with the hypothesis that multiple factors, rather than a single culprit, are at play in the disadvantage in mortality and it could explain, at least in part, the extraordinarily high cost of health care in this country.