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Correlation Does Not Necessarily Equal Causation


That’s a Rogue Medic like post title, isn’t it?

Death risks higher for heart attack survivors living near major roadways

Heart attack survivors who live about 100 meters (328 feet) or less from a major U.S. roadway face increased risk of death from all causes, according to new research in the American Heart Association’s journal Circulation.

In the Determinants of MI Onset Study of 3,547 heart attack survivors (average age 62), researchers found:

  • Those living less than 100 meters (328 feet) from the roadway have a 27 percent increased risks of dying over 10 years than those living at least 1,000 meters (3,280 feet) away.
  • Those living 100 to 199 meters (328 to 653 feet) from the roadway have a 19 percent increased risks of death.
  • Those living 200 to 999 meters (653 feet to 3,277 feet) from the roadway have a 13 percent increased risk of death.

Those are the hard numbers, but what do they mean? Do people who are more ill tend to live in more urban areas and closer to major roadways? Are there implications of an urban life style versus a rural one?

We think there is exposure to a combination of air pollution near these roadways and other exposure, such as excessive noise or stress from living close to the roadway, that may contribute to the study findings,” said Murray A. Mittleman, M.D., Dr.PH, study author and director of the Cardiovascular Research Unit at Beth Israel Deaconess Medical Center in Boston, Mass.

In this case I have to wonder if thinking = guessing.

“People with lower levels of education and income are more likely to live in communities closer to a major roadway, so they are bearing a larger burden of the risk associated with exposure than people with more resources” said Mittleman, who is also associate professor at Harvard Medical School.

People with lower levels of education and income are also less likely to go to follow up appointments, understand or follow doctors instructions, get prescriptions filled, and be diligent in taking prescription medications. Not to mention less likely to eat healthier foods, because as any home economist can tell you, junk food costs less than healthy food. I wonder if the researchers went to any of the homes that were close to the highways and observed first hand the living conditions of the people who were more likely to die? Or the people who were more likely to live for that matter?

OK, I’ll give you a required warning here. As Rogue Medic says, the plural of anecdote is not data. I, on the other hand, refer to them as observational data. While I don’t have a grant and thus couldn’t do a double blind study, I can tell you that from my years in EMS that ER (and other specialty) physicians for the most part have no idea what the living conditions of their patients are. Maybe primary care doctors do, but often they are only tangentially involved in the in hospital care of their patients. I’ve seen patients with implanted devices, such as central lines, sent home to incredibly filthy homes where there is not ONE person who can help them keep the injection sites clean, let alone sterile. People sent home on ventilators with only elderly, debilitated, relatives to take care of them. I think if some of these physicians were to visit the homes to which they are discharging patients, they’d be frankly shocked if not horrified.

“From the public policy point of view, the association between risk of death and proximity of housing to major roadways should be considered when new communities are planned,” Mittleman said. “From an individual point of view, people may lessen the absolute risk of living near a roadway by paying attention to the general prevention measures, including quitting smoking, eating a heart-healthy diet exercising regularly, and keeping blood pressure and cholesterol under control.”

Kind of reminds me of those ads for miracle weight loss drugs. “Our product, along with a healthy diet and regular exercise will help you lose weights. Of course results vary and there is no guarantee” I’ve got news for you, a healthy diet and regular exercise will help you lose weight without any miracle drug. In fact, health diet and regular exercise are the ONLY things proven to help you lose weight.

Since we don’t really know the exact causes of the increase in deaths, how can we make public or medical policy decisions based on this study? Hmmm…

And finally,

The Environmental Protection Agency and the National Institute of Environmental Health Science funded the study.

The EPA is a federal agency with a vested interest in proving that air is more, not less, polluted in the 40 years since the agency was created to clean up the environment. Only if they’ve been this ineffective in improving air quality, I have to wonder what they hell they’ve been doing with our money all these years?

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After a long career as a field EMS provider, I'm now doing all that back office stuff I used to laugh at. Life is full of ironies, isn't it? I still live in the Northeast corner of the United States, although I hope to change that to another part of the country more in tune with my values and beliefs. I still write about EMS, but I'm adding more and more non EMS subject matter. Thanks for visiting.


  1. Meh… concur with your comment. Just because there is a correlation, I would want to know a LOT more about the situations before I actually ‘assigned’ blame to the distance.

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