Economic freedom leads to longer life expectancy, higher per capita GDP, and more happiness (based on a Gallup index). The Heritage Foundation annually calculates an Index of Economic Freedom for most of the countries of the world, then assigns each country to one of five subgroups ranking from Free economy to Repressed economy.
Table 1 shows that Free countries have significantly higher life expectancies and do better in other quality of life measures:
Another way to reach the conclusion that freedom is the determining factor is to compare very similar peoples where the major difference is freedom. An extreme example is repressed North Korea vs. mostly free South Korea. Or the Chinese people in free Hong Kong, mostly free Taiwan, and the mostly unfree Peoples Republic of China.
Economic freedom leads to health, wealth and happiness. Lack of freedom leads to death, poverty and misery.