Keg Registration Paradox

I’m attending the Research Society on Alcoholism conference in Washington, DC right now. It’s always an interesting meeting with some of the top researchers in the field sharing their emerging findings.

I was struck by one little strange finding on a poster by James Fell and his PIRE colleagues (Fell, Fisher, Voas, Blackman, & Tippetts) titled The relationship of 16 underage drinking laws to reductions in underage drinking and driving fatal crashes in the United States. They found some impressive declines (16%) in fatal crashes resulting from a core set of laws restricting sale and possession to those under 21. But one finding puzzled the researchers: keg registration laws correlated with an increase in fatal crashes (12%) among those under 21.

What’s going on? According to Jim Fell, they also found that beer consumption went down for young people in the states with keg registrations. So beer consumption was down, but alcohol-related traffic fatalities went up. Frankly, I was not surprise. There have been a number of studies that have found keg parties result in lower intoxication levels than other forms of alcohol-service parties at colleges; we, along with our PIRE colleagues even published one of them (Clapp, Lange, Min, Shillington, Johnson & Voas, 2003). We found that “Bring Your Own Beverage”, often the opposite of a keg party, resulted in higher levels of consumption.

Perhaps it’s time to acknowledge that kegs of beer are, in fact, a protective form of alcohol service for young people. Of course one can get very drunk at a “kegger.” Of course, a big barrel of beer is worse than one small can of beer. But if young people are intent on drinking, it is better to make them fight through a crowd to get to nasty-cheap beer with low alcohol content than to push them towards taking shots of liquor. Fatal alcohol poisoning is far more likely from distilled forms of alcohol because it is very easy to consume the alcohol faster than it absorbs through the stomach into the blood stream. Beer can be consumed very quickly too, but it takes far more effort to do it over consumption is thus far less likely to occur with beer. If intoxication is lower, than risk of fatal crashes will decline too.

I am in this business to save lives. Keg registration has never been shown to save lives, and now is actually showing the opposite effect. People who promoted it were working with the best intentions and logic, but not empirical evidence. We have to start believing our own data, even when it comes out in a direction we aren’t expecting. I’m now convinced that we should stop demonizing kegs, permit them as we once did, and perhaps begin the shift back to this less potent form of alcohol. It may just save some lives.

Fuzzy estimates of BAC

The following article I wrote was published in the The Network: News From the Front email newsletter on April 18, 2008. Because it does not appear that this newsletter is still being archived on the web, I've placed it here as well:

If you've been following the controversy over the term binge drinking you'd know that a few years back, the National Institute for Alcohol Abuse and Alcoholism (NIAAA) settled on a new definition. They chose to eschew the often-used consumption-based definition of 5 or more (4 for women) drinks in favor of a new criterion. Their definition is "a pattern of drinking alcohol that brings blood alcohol concentration (BAC) to 0.08 gram percent or above. " Unfortunately, they included an example that some have latched on to as the definition: "this pattern corresponds to consuming 5 or more drinks (male), or 4 or more drinks (female), in about 2 hours." But while some have adopted this 2-hour timeframe as the new 5+/4+ definition, doing so misses the point. There are lots of ways to reach 0.08, and NIAAA was offering an example of just one. So if you're interested in using BACs as a criterion for risky drinking, then you'll need a way to convert consumption patterns into resulting BACs. Estimation formulas are the answer. But what's the science behind those estimates? Are the estimates valid?

Two recent studies call into question our ability to use self-reported consumption to accurately estimate BACs for college students. First, Hustad and Karey (2005) reported that when they compared breath-test alcohol concentrations (BrAC) with estimated BACs (eBAC) among college-student partygoers, the correlations were good, but the amount of variance between the estimates and the BrAC was substantial. Estimates were particularly off when consumption was high. Second, Clapp and his colleagues (myself included) similarly found deviations between estimates and BrAC (Clapp, et al, 2006). In fact, we found that only 24% of the cases yielded eBACs that were within ± 0.02 g/dl of the BrAC. And for those 76% of the cases that were off, the margin of error was huge. Worse yet, the error was in part dependent on factors such as party size and consumption amounts.

Where do the formulas go wrong? It's difficult to say with the existing research; however, the problem likely rests in a number of factors. One is that the estimation formulas rely on accurate reporting of consumption in "standard drink" units. In the U.S., that's a drink with 14 grams of alcohol. Even with simple beverages like canned beer, alcohol content can vary by as much as 50% from brand to brand. In other words, 4 cans of one brand can equal 6 cans of another. So it is not surprising that subjects find it difficult to report accurately. Indeed, research has been quite clear that people find reporting standard drinks problematic. Aside from this, others may fail to properly track the number of drinks, or the drinking event's duration; intoxication likely interferes directly with report accuracy. The motivation to fudge not only consumption but also reported weight might also play a role. These factors compound error stemming from estimation formulas that gloss over wide variability within individuals on alcohol absorption and metabolism rates.

What can we do? Well, until better estimation procedures are developed, we need to be more cautious about the statements we make. Our drink-quantity advice needs to reflect the variability between students. And even our program evaluation activities need to treat eBACs humbly. An intervention may result in more accurate reporting, changing resulting eBACs without any change in the underlying drinking behavior or problems.