(Originally published by Stanford Medicine on April 4, 2022)

Residents who don’t own a handgun but live with someone who does are significantly more likely to die by homicide compared with those in gun-free homes, research shows.

Stanford researchers and their colleagues have found that Californians who didn’t own handguns but lived with handgun owners were more than twice as likely to die by homicide compared with those living in gun-free homes.

Most strikingly, they found in a recent study that people who lived with a handgun owner were seven times as likely to be shot and killed by a spouse or intimate partner. Eighty-four percent of those victims were women.

The research adds to a growing body of evidence showing that having a gun at home is associated with a higher risk of fatal injury.

“Despite widespread perceptions that a gun in the home provides security benefits, nearly all credible studies to date suggest that people who live in homes with guns are at higher — not lower — risk of dying by homicide,” said the study’s lead author, David Studdert, LLB, ScD, a professor of health policy at the Stanford University School of Medicine and a professor at Stanford Law School.

Pandemic prompts gun buying

He added that Americans purchased firearms at a record-breaking rate during the COVID-19 pandemic, with surveys showing the main motivation was to protect themselves and their families.

The study, published April 4 in the Annals of Internal Medicine, examined homicide rates among nearly 17.6 million registered voters in California 21 and older. None of them owned handguns, but nearly 600,000 began living with handgun owners between October 2004 and December 2016, when someone in their household bought a handgun or when they started sharing a home with a handgun owner.

The researchers found that people who lived with handgun owners were 2.33 times as likely to become victims of homicide and 2.83 times as likely to die from homicides involving firearms. Among people killed at home, those living with handgun owners were 4.44 times more likely to be fatally shot than neighbors living in gun-free homes.

“Our goal was to estimate the effect of household exposure to handguns on nonowners’ risk for dying by homicide,” the researchers wrote. “We were particularly interested in homicides occurring in or around the home because protecting one’s home is a major motivation for gun ownership, and a plurality of homicides occur in the home.”

Women most at risk

Yifan Zhang, a research scholar in the Department of Health Policy and study co-author, noted that two-thirds of the people they studied were women. “It’s important to recognize that women bear the brunt of the elevated risks we identified, and that the fatal assaults they experienced often took the form of being shot by men they lived with,” she said.

The researchers did not find evidence that people living in homes with guns had lower risks of being killed by strangers. On the contrary, they found that risks of such deaths appeared higher, although the result was not statistically significant.

Only one previous study has quantified the risks faced by people who do not own guns but live with others who do. It was conducted 25 years ago and examined too few deaths to reach clear conclusions, the researchers wrote.

An earlier study by the research team using the same cohort found that men who own handguns were eight times more likely to die of gun suicides than men who don’t own guns — and female handgun owners were 35 times more likely to die this way.

“The evidence that gun access is associated with higher suicide risk is now overwhelming,” said Matthew Miller, MD, ScD, a professor of epidemiology at Northeastern University and the senior author of the study.

“Tolerating that suicide risk could, in theory, be worthwhile if firearm ownership enhanced personal safety in other ways. This study shows there’s no such trade-off, because the risk of fatal assault in homes with guns is higher too, and the gun owner’s family members bear a lot of that risk.”

Other Stanford co-authors of the study are research assistant Erin Holsinger, MD; former research data analyst Lea Prince, PhD; former research assistant Alexander Holsinger; and Jonathan Rodden, PhD, professor of political science.

Garen Wintemute of UC Davis also contributed to the work.

The study was funded by the National Collaborative on Gun Violence Research, the Fund for a Safer Future, the Joyce Foundation, Stanford Law School and the Stanford University School of Medicine.