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Sunday, August 31, 2003"'If these results hold up, then building compact communities will become a public health imperative, given our obesity epidemic." Trouble is, these results don't hold up: People who live in the most spread-out areas spend fewer minutes each month walking and weigh about six pounds more on average than those who live in the most densely populated places. Probably as a result, they are almost as prone to high blood pressure as cigarette smokers, the researchers found. Six pounds up or down doesn't make much difference in the BMI of a person, unless they happen to be just on the borderline. It doesn't even make much difference in clothing size.And the correlation between sprawl and girth is even less impressive: A 50-point increase in the degree of sprawl was associated with an average weight gain of a little more than one pound per person, researchers found. But 50 points on the scrawl scale is a fairly large spread: The index ranged from a low of 63 for the most sprawling county -- Geauga, Ohio, just outside Cleveland -- to a high of 352 for the densest -- New York City. Geauga county is a county of large, expensive houses on widely separated, expansive tracts of land. It's a county of horse farms and nature preserves. (They even play polo up there, believe it or not.) New York City, on the other hand, is a place where people live right on top of one another, where the sun is obscured by buildings, and the sight of a tree is hard to come by. What are the chances that the difference in average weight is more likely to be due to comparing the average of a small number of people to the average of a large number of people? Pretty good, I'd expect. In fact, I bet if they compared the average weight of the population of South Dakota, or of Vermont, with the average weight of the population of New York City, South Dakotans and Vermonters would come out heavier - even though they live in rural areas with small towns that encourage walking and bike riding. Then there's that "probably" and the health effects of living in suburbia: While researchers found no association between sprawl and diabetes or heart disease, they did find that people who live in the least sprawling areas had a 29 percent lower risk of developing high blood pressure than those in the most sprawling areas. The researchers, of course, don't tell us exactly what that 29 percent reduction represents. Do 100% of people in sprawl areas have high blood pressure compared to 71% in densely populated urban areas? Or do 1% of people in sprawl areas have high blood pressure compared to 0.71% in dense urban areas? Probably somewhere in between, but much closer to the latter than the former. No way of telling, however, since the study is not available unless you're willing to pay for it. And judging by this study, it doesn't appear to be worth the money. And Another Thing: For years people have been blaming urban living for obesity. They argue that people living in the inner city are afraid to leave their apartments (at least in poor neighborhoods) and that children have to sit inside in front of the television because there is no place to play. But of course, looking into that connection wouldn't fit the current public health political ideology. UPDATE: A reader reminds me that there's another downside to urban living that's often mentioned in the media but forgotten in this particular article - the higher incidence of asthma in urban areas: Another point to make in the obesity and sprawl critique: If one compared Geauga and New York City and claims that the latter will have less weight gain, then it's only fair that we examine one other potential effect of sprawl: exposure to pollution. Wonder what the average particulate count, ozone concentration and NO2 concentration is at each location? Sure, it's hard to know what small differences in air quality mean to health overall, but if the National Center for Smart Growth is allowed to speculate out their heinie about the potential effects of a few pounds on health, I'm certainly allowed to speculate on the difference in a few parts per million in air quality. UPDATE II: Another reader says my headline sounds like a porno movie (that should help traffic) but also has these thoughts to share about the proliferation of "studies": I doubt that there is more misused term in this innumerate country than "study", as the vast majority of those reported in the press are nothing but data-mining, with the conclusions carefully decided beforehand. The rest are collections of breathless, but ultimately meaningless, "testimonials" for some overpriced (and probably un-needed) dietary supplement. I'm probably grumpy because I just spent twenty minutes trying to explain the difference between a real controlled "study" and these exercises in hype-by-press-release to a patient who is paying sixty dollars a quart for what is essentially sea water. "Oh, but they have lots of studies to prove it works". Went to their website- you guessed it, the "studies" page is "under construction"! HA! Yeah. No matter what you want to believe, there's a "study" that'll back it up. Medicine is getting to be more and more like a social science. posted by Sydney on 8/31/2003 08:10:00 AM 0 comments 0 Comments: |
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