PHILADELPHIA – In a first-of its-kind study, epidemiologists at the University of Pennsylvania School of Medicine found that, on average, guns did not protect those who possessed them from being shot in an assault. The study estimated that people with a gun were 4.5 times more likely to be shot in an assault than those not possessing a gun.

The study was released online this month in the American Journal of Public Health, in advance of print publication in November 2009.

“This study helps resolve the long-standing debate about whether guns are protective or perilous,” notes study author Charles C. Branas, PhD, Associate Professor of Epidemiology. “Will possessing a firearm always safeguard against harm or will it promote a false sense of security?”

What Penn researchers found was alarming – almost five Philadelphians were shot every day over the course of the study and about 1 of these 5 people died. The research team concluded that, although successful defensive gun uses are possible and do occur each year, the chances of success are low. People should rethink their possession of guns or, at least, understand that regular possession necessitates careful safety countermeasures, write the authors. Suggestions to the contrary, especially for urban residents who may see gun possession as a defense against a dangerous environment should be discussed and thoughtfully reconsidered.

A 2005 National Academy of Science report concluded that we continue to know very little about the impact of gun possession on homicide or the utility of guns for self-defense. Past studies had explored the relationship between homicides and having a gun in the home, purchasing a gun, or owning a gun. These studies, unlike the Penn study, did not address the risk or protection that having a gun might create for a person at the time of a shooting.

Penn researchers investigated the link between being shot in an assault and a person’s possession of a gun at the time of the shooting. As identified by police and medical examiners, they randomly selected 677 cases of Philadelphia residents who were shot in an assault from 2003 to 2006. Six percent of these cases were in possession of a gun (such as in a holster, pocket, waistband, or vehicle) when they were shot.

These shooting cases were matched to Philadelphia residents who acted as the study’s controls. To identify the controls, trained phone canvassers called random Philadelphians soon after a reported shooting and asked about their possession of a gun at the time of the shooting. These random Philadelphians had not been shot and had nothing to do with the shooting. This is the same approach that epidemiologists have historically used to establish links between such things as smoking and lung cancer or drinking and car crashes.

“The US has at least one gun for every adult,” notes Branas. “Learning how to live healthy lives alongside guns will require more studies such as this one. This study should be the beginning of a better investment in gun injury research through various government and private agencies such as the Centers for Disease Control, which in the past have not been legally permitted to fund research ‘designed to affect the passage of specific Federal, State, or local legislation intended to restrict or control the purchase or use of firearms.’”

This study was funded by the National Institutes of Health. The authors are also indebted to numerous dedicated individuals at the Philadelphia Police, Public Health, Fire, and Revenue Departments as well as DataStat Inc, who collaborated on the study.

Therese S. Richmond, PhD, CRNP, School of Nursing; Dennis P. Culhane, PhD, School of Social Policy; Thomas R. Ten Have, PhD, MPH, and Douglas J. Wiebe, PhD, both from the School of Medicine, are co-authors.