Posted Monday, March 28, 2011, at 12:27 PM
When the "new" car seat guidelines came out last week, particularly the one suggesting that tweens stay in their booster seats until they're 12 (or 4 feet 9 inches, whichever comes first) I posted about them with a nagging, irritated thought in the back of my head: Hadn't someone, somewhere, done a study that showed that booster seats weren't any more effective than seat belts in preventing fatalities in children older than 6?
The answer was yes--but with nothing but a faulty memory and some far too common search terms, I didn't find it until late last week, via my social network full of nit-picking, study-reading lawyers. It was Steven Levitt and Stephen Dubner for their book SuperFreakonomics , and they didn't just analyze the data sets that are currently available (the same data sets used in the current AAP recommendations, incidentally, the study referenced in the report behind the recommendation is nearly 20 years old)-they commissioned their own study. Using an anonymous lab (which was extremely reluctant to do the tests and insisted on anonymity to preserve their car-seat testing business), Levitt and Dubner tested not booster seats vs. nothing but booster seats vs. lap-and-shouldner belts on 3- and 6-year-old crash test dummies.
They found no difference in fatalities in either. As they said, "[I]f we submitted our data from the seat-belted dummies to the federal government and said it came from the latest and greatest car seat," it would easily win approval. But there's another argument for using booster seats rather than belts. What about preventing not fatalities but injuries? Child safety advocates argue that lap-and-shoulder belts alone can actually cause injury to children. So Levitt and Dubner analyzed that data as well and found that for "preventing serious injury, lap-and-shoulder belts once again performed as well as child safety seats for children aged two through six." But for reducing minor injuries, car seats did a far better job-on younger kids. As for kids over 6, there's really no hard data, and there was nothing new in last week's report.
So-for kids under 6, the booster is an easy call. But what about for those preteens who parents everywhere are now supposed to be popping back into their booster seats, based not on some dramatic new finding but on the same studies that have been around for two decades (on, as even the AAP admits, a much older vehicle fleet)? Not only is there nothing new; there's no evidence other than our gut urge to believe in the power of the safety device and the media's urge (including mine) to promote the recommendation that's likely to get the most clicks. If you read not just the recommendation but the report behind it, and then dig back into the reports cited within it, it's clear that (as Levitt and Dubner also point out) the study suggesting evidence for the reduction of serious injury in the 4-7 age group (which was used to extrapolate the recommendations for older children) is based on parent reporting of the use of restraining devices and did not distinguish between children using lap-only belts and those using lap-and-shoulder belts. In other words, it's dubious. For kids using lap-only belts, in fact, the same study author (as well as the author of the current report) does not recommend the use of a booster seat at all .
What does all this mean for the well-intentioned parent of a 4-foot-7 8-year-old? It means that if your kid wasn't in a booster seat in February, nothing new was discovered in March to change where you should seat your child. I'm not anti-booster seat. I have three in my car right now, and one under a no-real-evidence-of-increased-safety almost 7-year-old. Like you, I'd far rather be safe than sorry (and I'd kind of like to look into the back seats of Levitt and Dubner's cars). I'm anti making a big deal about new recommendations without any new, or even much of any, evidence behind them.
Worse, there were other interesting, headline-suggesting new findings within that report. How about this one: Hispanic and non-Hispanic black children, along with American Indian children, are still more likely to die in a traffic accident? Or this seriously disturbing trend: 89 percent of white teens wear their seat belts. 82 percent of Hispanic teens do, too-but only 46 percent of non-Hispanic black teens buckle up.
Net-net on last week's child-car-seat headline mania? Once again, the media (and this time I fell into it, too) focused on the easily panicked parent story, rather than the one with greater societal implications but with a smaller personal impact on the particular subset of targeted readers. (Incidentally, the recommendation that kids remain rear-facing until at least 2 also came from older, although far more compelling, data as well as a reference to Sweden, where kids stay rear-facing until 4, no doubt at great cost to their parents' car upholstery and sanity but at some apparent gain to their safety.) And the lesson is pretty much what the lesson always is: If you're going to change your behavior based on a study, wait until you've actually read it yourself.