Blog | Monday, October 16, 2017

ZIP codes of medical destiny


When the PURE diet study papers roiled headlines around the world recently, I wrote an admittedly lengthy analysis. I didn't feel I had much choice; the publications encompassed three distinct research papers, reams of data, and a whole lot of what proved to be mostly misguided interpretation of the findings by the media, and the investigators themselves. Getting the story sorted out reliably involved some heavy lifting, and considerable verbiage.

But, in the mix, was my succinct, summary judgment about the whole thing: poverty undermines reasonable eating. That, really, was the key message.

Officially, PURE stands for “Prospective Urban and Rural Epidemiology,” but I think “Poverty Undermines Reasonable Eating (and health, by the way)” would sum it up quite nicely. By way of brief reminder for those who already knew: The people in PURE who ate the most vegetables, fruits, and legumes had, by far, the lowest mortality rates. The people who ate the fewest vegetables, fruits, and legumes had by far the highest.

If you are thinking that simple assertion is a very odd place for headlines telling us that vegetables and fruits no longer do anything for health this week, I am with you entirely. How was that even possible?

Well, the PURE populations with the best diets also had the best of everything else: educations, jobs, homes, safe environments.

In contrast, there were populations included in the study from some of the poorest countries on earth, notably Bangladesh and Pakistan, where high intake of “carbohydrate” was associated with high mortality rates. But the blame here, rather blatantly, did not reside with a macronutrient, but with macroeconomics.

These were people dealing with poverty, all manner of deprivation, and getting by on little more than white rice; or, in the case of Zimbabwe, maize. We can all readily accept that a diet comprised almost entirely of just one food―any one food―because you have no other choices is a bad thing.

That would be true if the one food were broccoli, or butter; bacon or beans ― let alone white rice, or maize. The simple fact is, though, that rice and corn and wheat are among the least expensive, most readily available foods in subsistence populations, so when people are scraping by and trying not to starve, these ― and neither broccoli nor butter ― tend to be at hand. Thus, the utterly meaningless association between “carbohydrate” and mortality issuing from PURE. What is associated with mortality, and morbidity, for many reasons, is poverty, and its many henchmen: hunger, thirst, struggle, and a destitution of resources.

All of which is just a prelude to this week's study, perhaps not generating the headlines it should. An article just published in Annals of Internal Medicine reported health outcomes in nearly 110,000 people who had undergone cardiac risk assessment in the Cleveland Clinic Health System. The researchers applied the Pooled Cohort Equations Risk Model (PCERM) of the American College of Cardiology and American Heart Association and compared the predicted rate of cardiac events to actual occurrence.

The “punch line” in this case is just about as blunt as a literal punch to the gut: the model significantly under-predicted cardiac event rates “among patients from disadvantaged communities.” In other words, socioeconomic disadvantage- poverty and its baggage-caused heart attacks and deaths that otherwise should not have occurred.

This is, obviously, directly germane to the massive misrepresentation of the PURE papers that were yesterday's news. It is germane to tomorrow's public health news, too.

The message in the much-distorted reporting of PURE, hiding in plain sight, is that the social determinants of health―the basic circumstances of our lives and environments―prevail.

One of the great, and from my perspective distracting and fairly useless debates of modern public health is whether responsibility for the prevalent ills of modern society is more personal, or public. The debate is useless in that it tends to polarize an issue best situated in the middle.

Clearly, personal responsibility for health matters. No one else can exercise for you; no one else will put food in your mouth―but for rare and rather dire circumstances. At the end of the day, what you and I do with our feet, our forks, and our fingers (e.g., holding cigarettes) is up to us.

On the other hand, how preposterous to suggest that the playing field of opportunity for health is level. Some of us have every relevant advantage, with facilities readily available for exercise year round, indoors or out, and a choice among the most nutritious foods throughout the year. Others of us live in food deserts, where streets are unsafe to walk, where a recreational facility is a parking lot frequented by gang members, and where gym membership either doesn't exist, or is an unaffordable luxury and far lesser priority than protecting one's kids from ambient drugs and violence.

We have yet another reminder of the importance of such factors in a report on childhood obesity just released by the USDA. Obesity is far more common among children in overtly disadvantaged households.

Those admonishing all to make good behavioral choices may conveniently overlook that the choices any of us makes are ineluctably subordinate to the choices we have―and we simply don't all have the same choices. That the PURE analysis overlooked this was not only a failure of Epidemiology 101; it was a nearly paradoxical failure at the human level for a study intended to help us better understand the disparities between populations with and without every modern advantage.

In their seminal paper nearly a quarter century ago, McGinnis and Foege told us of the “actual” causes of premature death in the United States, attributing nearly 80 percent of the total to just three lifestyle behaviors: smoking, poor diet, and lack of physical activity. For those of us in lifestyle medicine, this has been a compelling mandate all the while. But we are obligated to recall that lifestyle behaviors are the choices we make; social determinants are the choices we have. We are obligated to recall that even causes have causes. We are obligated to recall that sometimes, the best and only defense of the human body resides with the body politic.

There is much many of us can do with lifestyle choices to impact our medical destiny. But sometimes the critical matter is neither a choice we can make, nor our lipid panel, nor our genetic code. Sometimes, it's our ZIP code.