derifatives

Life Expectancy, and Its Cousins

We've all heard it. "The US spends twice as much money per capita as most other countries on healthcare, yet our life expectancy is lower." Here's a graph from 538.com showing the result. Reid, on p. 241, says:

"The world's richest country ranks forty-seventh... The United States is among the worst of the industrialized nations on this score... the quality of, and access to, national health care plays a large role in any country's average life expectancy; the fact that tens of millions of us don't have access to a doctor means Americans are dying of health problems that would probably be cured in any other developed country."

My goal in this post is to argue that the final sentence of this quote is false, and that in fact, the quality of and access to national health care plays a very small role in any country's average life expectancy.

An article from the National Center for Public Policy Research makes the point that for a statistic to be good for comparing healthcare systems across nations, it must (a) assume an actual interaction with the health care system, and (b) measure a phenomenon that the health care system can actually affect. For example, a statistic measuring rates of cancer survival satisfies both (a) and (b), a statistic measuring rates of cancer incidence only satisfies (a), and a statistic measuring homicide rates satisfies neither. How well does life expectancy do?

Well, the US has extremely high rates of both homicides and traffic accidents, and according to at least some studies, correcting for just these factors moves us up substantially in the rankings. More importantly, the weight of evidence supports the idea that a number of other issues including genetics, diet, lifestyle and culture play a much larger role in life expectancy than the healthcare system does. This study from Harvard examines life expectancy by race and demographics in some detail. While many people know that black Americans have much worse life expectancy than whites [even after controlling for the much higher accident and homicide rate], this can easily be explained by either genetic and cultural differences or the argument that blacks have worse access to healthcare. On the other hand, the results for Asian Americans are pretty striking. Comparing Asian Americans as a group to "middle America" [white Americans with a couple of identifiable large poor rural populations in the north and Appalachia removed], the middle America group has a much higher average income, a somewhat higher high school completion rate, better access to healthcare, and a much lower life expectancy. In fact, the Asian population in the US has a higher life expectancy than the Japanese population, which has the highest country-level life expectancy in the world. Comparing Mormon and non-Mormon whites in Utah, the Mormons had much higher life expectancies, even after controlling for tobacco usage; the study suggests that "may be due to factors associated with religious activity in general, such as better physical health, better social support, and healthier lifestyle behaviors. Religious activity may also have an independent protective effect against mortality." In this paper, researchers at the University of Pennsylvania's Population Studies Center examine these issues in detail, stating that

"We consider in greater depth mortality from prostate cancer and breast cancer, diseases for which effective methods of identification and treatment have been developed and where behavioral factors do not play a dominant role. We show that the US has had significantly faster declines in mortality from these two diseases than comparison countries. We conclude that the low longevity ranking of the United States is not likely to be a result of a poorly functioning health care system."

Reid himself mentions that life expectancy is a problematic metric, although he ignores the issues I mentioned above. Instead, he concentrates on the idea that quality of life is important, and suggests the DALE, or Disability-Adjusted Life Expectancy, which is a complicated formula developed by the World Health Organization that ranks people with various conditions. Reid states:

"Still, the U.S. ranking in DALE terms, twenty-fourth, is considerably higher than the forty-seventh place we scored on the simpler ranking of life expectancy at birth. That difference means that American health care is making people healthier &mdash at least, for those who have access to it. It's because we fail to provide access to regular health care for 45 million Americans that our overall rank for healthy life expectancy trails the rest of the developed world."

Although Reid frequently cites statistics and studies in his book, there is no reference or support for his simple assertion about why our DALE score falls where it is. Yet DALE is subject to all the same problems I discussed above. In fact, given the high rate of accidents and non-health mortality in the US, it is highly plausible that the US currently looks great in DALE at the country level. Other metrics, such as QALY and DALY, suffer from exactly the same problem.

If government provided healthcare strongly improved health outcomes, we should expect that the introduction of Medicare, offering government provided healthcare to the entire elderly population of the United States, should have had a huge effect. But NBER economists Finkelstein and McKnight studied the impact of the introduction of Medicare and found that

"the introduction of Medicare had no discernible impact on elderly mortality in its first ten years in operation. They present evidence suggesting instead that, prior to Medicare, elderly individuals with life- threatening, treatable health conditions (such as pneumonia) sought care even if they lacked insurance, as long as they had legal access to hospitals."

[Finkelstein is now at MIT; the paper is available free at her website.]

I welcome pointers to studies that take the other position here, but I have not yet found any studies that convincingly argue [rather than merely stating] that changes to our healthcare system could on their own have a large effect on country level life expectancy. The US is a diverse country, much more diverse than most of the European countries we're comparing against.

National health care is a large intervention in the economy. If you're going to use differences in statistics like life expectancy or infant mortality to argue for national health insurance, you should be able to present a compelling case that these statistics are strongly under the control of the healthcare system, and that a national healthcare system has a good chance of greatly improving these statistics. I believe that supporters of national health care use these statistics, but in a superficial and unjustified way. I haven't proved that national health care is "wrong", or that we shouldn't do it. But I hope I've shown that arguments talking about differences in life expectancy [or DALE's or QALY's] do not justify an enormous costly intervention in the economy, because there is little evidence that these measurements are strongly under the control of the healthcare system.

[Note: In the developed world, life expectancy is still increasing noticeably relative to the scale of differences between countries. Results from 2000 which are still floating around the web look different from results from 2006 or 2008. So if you want to use absolute numbers, be very careful about using the same dataset.]