FRIDAY, June 30, 2006 (HealthDay News) -- The more bars that open their doors for business in a neighborhood, the greater the likelihood that violence will follow.
That's the conclusion of a study in the July issue of the journal Alcoholism: Clinical & Experimental Research in which researchers analyzed the relationship between alcohol outlets and overnight hospital stays due to assaults.
"We have believed that is true, but we have never had a longitudinal study that provides us with a causal argument," said Paul J. Gruenewald, a senior research scientist at the Prevention Research Center, in Berkeley, Calif. "Before this study, we have known that areas with larger numbers of bars have more violence. Now, we know that increasing the number of bars will increase the violence," he said.
To do the study, Gruenewald used hospital discharge data from the state of California that is carefully tracked and classified by injury cause. About one in 10 assaults recorded by police are serious enough to require hospitalization, he said, so by looking at hospital discharge data on assaults, he knew he could capture for analysis the most severe incidences of violence against people.
Gruenewald collected six years' worth of data from 581 different ZIP code areas. He correlated household size and retail businesses with the hospital admission data for violent assaults.
While Gruenewald can't yet answer the question of how many bars is too many, he did find that the addition of one bar to the average ZIP code area would produce about 0.17 more hospitalized assaults each year, or one assault for every six bars.
Until now, he said, "there has been no evidence that increasing or decreasing the number of bars will affect the level of violence in a community. This demonstrates that increasing the number of bars will lead to an increase in violence."
Violence also increased in areas with large male populations, the researchers found, and in areas with a greater percentage of minorities and lower-income households.
While the study just looked at California data, Gruenewald said, "it's probably true in all states."
One of the next areas of research, he said, should be: "How can we decide how to reduce the number of outlets, and what is the best regulatory strategy?"
Gruenewald said the alcohol industry typically supports "server intervention," in which a server doesn't supply an inebriated patron with any more liquor, as well as adhering to designated-driver practices to reduce drunkenness and violence.
But, of the strategies, he said, "There is very little evidence they work at all to stop drinking and driving."
In another study in the same journal, researchers from the University of Minnesota found that bars with managers with more than one year of employment are more likely to sell liquor to intoxicated patrons.
One possible explanation: It may be they feel comfortable on the job and less bound to follow the rules. The researchers also found that bars that hold regular staff meetings and have full liquor licenses are less likely to sell to intoxicated patrons, but the rates are still high -- 59 percent.
The Minnesota researchers hired professional actors to pretend they were drunk and try to purchase alcohol at 231 bars and restaurants. Then, the researchers did a phone survey of the establishment owners and managers. "Drunk" patrons were able to buy alcohol in 65 percent of the attempts.
Neither of the two studies surprised Dr. Wally Ghurabi, chief of emergency services at Santa Monica-UCLA Medical Center, in Santa Monica, Calif. "Alcohol disturbs our clear thinking. You become euphoric, you think you are king of the road," he said.
Ghurabi and other emergency-room doctors know that when bars close, "then you see all the cuts and bruises."
In his experience running an emergency department, Ghurabi said, "the more people have access to alcohol, which correlates with the number of outlets, the more assaults. There's no question in my mind that this [study] correlates very well with what I have seen over the years."
To learn more about alcohol and alcohol abuse, visit the National Institute on Alcohol Abuse and Alcoholism.