The study looked at how health and wealth are connected in 13 countries over the past 200 years. They found that as people live longer, the total GDP and GDP per person go up. A 1% increase in life expectancy leads to a 6% rise in total GDP and a 5% increase in GDP per person in the long run. The researchers also discovered that the total GDP and GDP per person have an impact on life expectancy in most countries. These relationships have stayed consistent over time, showing that changes in what makes people sick or die haven't changed the link between health and economic growth.