Back in June I railed against an infographic that claimed that health care played only a 10% role in our health. I followed the "studies" the infographic cited, but they led to a dead end. A reader tried another approach, but still couldn't find anything to back up the 10% figure. Meanwhile, David Cutler has written that half our longevity gain since 1950 is due to health care. I've spent some time reading further into the literature that Cutler cites for this claim. This post summarizes some of it. Cutler, Rosen, and Sandeep (NEJM 2006) find

that 90 percent of the increases in life expectancy during the past four decades have resulted from reductions in the rate of death from cardiovascular disease and death in infancy.
Actually, according to the figures elsewhere in the paper, it's 89%, most of it due to cardiovascular disease (70%) and a big chunk of the rest from infant mortality (19%). Therefore, if it is plausible that about 55% of reductions in mortality for cardiovascular disease and in infancy are due to medical care, then one can reasonably conclude that health care is responsible for for half (~89% x 55%) of longevity gains since the middle of the 20th century. It's actually trickier than this since a medical intervention that cuts infant mortality by 1% adds far more life years than a 1% reduction in death due to cardiovascular disease. But, let's see if something like 55% is plausible. Cardiovascular Disease Goldman, Cook (Annals of Internal Medicine, 1984):
Using reasonable assumptions gathered from the published literature, we estimated that more than half of the decline in ischemic heart disease mortality between 1968 and 1976 was related to changes in lifestyle, specifically to reductions in serum cholesterol levels and cigarette smoking. In comparison, about 40% of the decline can be directly attributed to specific medical treatment of clinical ischemic heart disease and hypertension being the leading estimated contributors.
Capewell, Morrison, McMurray (Heart, 1999):
In 1994, the total number of deaths prevented or postponed by all treatments and risk factor reductions was estimated at 6747 (minimum 4790, maximum 10 695). Forty per cent of this benefit was attributed to treatments (initial treatments for acute myocardial infarction 10%, treatments for hypertension 9%, for secondary prevention 8%, for heart failure 8%, aspirin for angina 2%, coronary artery bypass grafting surgery 2%, and angioplasty 0.1%). Fifty one per cent of the reduction in deaths was attributed to measurable risk factor reductions (smoking 36%, cholesterol 6%, secular fall in blood pressure 6%, and changes in deprivation 3%). Other, unquantified factors apparently accounted for the remaining 9%.
Hunink et al. (JAMA, 1997):
When secular changes in these factors were included in the model, predicted coronary mortality in 1990 was within 3% (10 000 deaths) of the observed mortality and explained 92% of the decline; only 25% of the decline was explained by primary prevention, while 29% was explained by secondary reduction in risk factors in patients with coronary disease and 43% by other improvements in treatment in patients with coronary disease. [...] In a previous analysis based on a literature review that evaluated changes from 1968 to 1976, 63% of the decline in CHD mortality was estimated to be owing to risk factor reduction, including reductions in blood pressure, and 31% owing to other medical interventions.
Unal, Critchley, Capewell (BMJ, 2005):
Modern cardiological treatments for known CHD patients, such as thrombolysis, aspirin, angiotensin converting enzyme inhibitors, statins, and coronary artery bypass surgery, generally explain the remaining 25-50% of the fall in mortality. [...] Medical and surgical treatments together prevented or postponed approximately 25 805 deaths (minimum estimate 17 110, maximum estimate 49 040). This represented 42% of the total decrease in CHD deaths estimated by the model.
Bajekal et al. (PLoS Medicine, 2012):
Previous country-level analyses have shown that about 50%–70% of the dramatic falls in CHD mortality between 1980 and 2000 were explained by improvements in modifiable risk factors (mainly smoking, total cholesterol and blood pressure), with the remaining 30%–50% attributable to improved uptake of evidence-based treatments. [...] Overall, [we find] approximately half of the total CHD mortality fall (19,780 fewer deaths or 52%; 95% uncertainly interval ranging from 40% to 70%) was attributable to improvements in uptake of medical and surgical treatments.
Infant Mortality Lee et al. (American Journal of Public Health, 1980):
It is a plausible hypothesis that improved perinatal medical care is a major factor in declining neonatal mortality in the U.S.
Richardson et al. (Pediatrics, 1998):
Mortality decreased nearly 50% for infants <1500 g in 5 years. One third of this decline is attributable to improved condition on admission that reflects improving obstetric and delivery room care. Two thirds of the decline is attributable to more effective newborn intensive care, which was associated with greater aggressiveness of respiratory and cardiovascular treatments.
Williams and Chen (NEJM, 1982):
Taken together, these data indicate that the major force in achieving dramatic decreases in perinatal mortality stems from advances in perinatal medicine that have been aggressive in the use of technology.
Conclusion There are other papers one could read on these topics, but this is all I had time for and/or could get in full text. From these, it looks like reasonable figures are 40% of reduction in cardiovascular mortality are due to medical care, while 66% or more of reductions in infant mortality are due to medical care. Therefore, I think Cutler's ballpark of 50% of longevity due to medical care is reasonable. However, it matters what time span one is considering. It is possible that we don't achieve that much additional gain from additional health care today (diminishing returns). Still, I have seen nothing to suggest the marginal gain is as low as 10%, as some claim. Also, some of the papers above consider fairly recent data. Since the vast majority of longevity gains are due to cardiovascular and newborn care, one might ask if other types of care are as valuable. Yet, in asking such questions, one must also keep in mind that health care is not just about longevity, but also quality of life, which includes both physical and mental well being. Treatment for my nearsightedness is very valuable, even if it does not increase the duration of my life. Finally, even if we can credit health care with 50% of our health improvement, that leaves plenty of room for other factors, and in particular, factors that are cheaper per unit of gain. Health care is valuable but still very expensive in the United States.  

Austin Frakt is a health economist at the Department of Veterans Affairs and Boston University’s Schools of Medicine and Public Health. He blogs on health economics and policy at The Incidental Economist.

As part of our ongoing effort to raise awareness of health services research and increase its application in policy and practice, AcademyHealth has partnered with Austin Frakt, Ph.D., and Aaron Carroll, M.D., M.S., to contribute posts on the subjects of health care costs, delivery system transformation, and public and population health – areas AcademyHealth has identified as a priority in the current policy environment. As regular contributors, they’ll be discussing current events with an eye toward how new and existing research informs the issues.