Although estimates vary, most analyses suggest that only about 10% of the variation in health outcome is attributable to medical care. Further, medical care is most effective in addressing and preventing infectious disease and acute illnesses. Recent large randomized clinical trials often fail to demonstrate that medical care lengthens life expectancy.

 http://www.sciencedirect.com/science/article/pii/S0091743514001455

http://www.sciencedirect.com/science/article/pii/S0091743514003715