A woman’s risk of dying by suicide was more than 40% higher after another adult in her household became a handgun owner, according to a retrospective cohort study of 9.5 million women.

Rates of suicide were 1.43 times higher (95% CI 1.11-1.84) among women living with handgun owners compared with those living in handgun-free homes. And the higher rate of overall suicide was driven entirely by a 4.32 times higher (95% CI 2.89-6.46) chance of dying by firearm suicide among women living with a gun owner compared with women who do not, Matthew Miller, MD, MPH, ScD, of Northeastern University Bouvé College of Health Sciences, and colleagues, wrote in JAMA Psychiatry.

The number of first-time gun owners in the U.S. has risen dramatically since the beginning of the pandemic. Yet, nine in 10 people living in homes with guns don’t believe that factor contributes to their own increased risk of suicide, said Miller, who is also director of the Harvard Injury Control Research Center in Boston.

“Most of the people who get guns, the great majority, are doing it because they want to protect, not imperil, the people in their home,” Miller told MedPage Today. “And we know from this work and other studies, that bringing the gun into the home is in fact doing just the opposite of what is intended.”

Given that 85% of the non-gun owner adults living in a household with gun owners are women, this study quantifies the “imposed risk” of firearm suicide and captures the increased risk when a cohabiting adult lawfully obtains a gun, he explained.

“It’s increasing her risk of firearm suicide by more than 400%,” Miller said, noting that a woman’s risk of suicide overall increased by “nearly 50%.” He added that firearm suicide is the leading cause of firearm deaths among women.

While previous studies found that, on average, having a gun in the home more than tripled the risk of suicide for those living in the home, those studies did not specifically isolate the risk for non-gun owners from the gun owners. For the new study, Miller and colleagues were able to separate out those risks.

Study Details

Miller’s group examined data from 9.5 women in non-gun-owning households from October 18, 2004, to December 31, 2016. Study participants were drawn from the LongSHOT database, which was comprised of three data sources: the California Dealer Record of Sale database, the California Statewide Voter Registration Database and the California Death Statistical Master File.

Of these women, 331,968, (3.5%) became “exposed to household guns” (with a mean age of 41.6) during the study. Of the entire study sample of women exposed or unexposed, 294,959 women died. In all, 2,197 (1%) died by suicide.

Among the 4,585 women exposed to handguns who died during the study period, 64 died by suicide versus 2,133 of unexposed women. This amounted to a “crude rate” of 5.84 suicides per 100,000 versus 4.14 per 100,000 suicides, respectively.

Drilling further into the data, Miller and his colleagues found that 31 of the 64 suicides among women living with handgun owners involved a firearm, whereas only 306 of the total 2,133 suicides of women not living with handgun owners were firearm suicide (crude rates of 2.83 per 100,000 vs 0.59 per 100,000, respectively).

Women living in households with and without handguns had similar rates of suicide by methods other than firearms (HR 0.90; 95% CI 0.63-1.27), the study showed.

The Mental Health Confounder

One limitation of the study, the researchers said, is that some women may have been miscategorized as living in homes without handguns, when their homes were not gun-free, the guns were obtained unlawfully or before January 1985 when California’s gun registry first started. So, instead of overestimating the magnitude of increased risk of suicide among women in households with guns, it would’ve underestimated the risk.

The sample was based solely on women in California, which may have affected generalizability, but the authors noted that they don’t believe that these women “differ from similarly situated women with respect to characteristics […] such as access to the firearms in their home or preferences for particular suicide methods.”

Miller explained they also did not adjust for mental illness, which was “perhaps the greatest threat to the validity of our estimates” since mental illness is a leading risk factor for suicide and thus, a confounding variable. To address that concern, Miller and his colleagues ran a negative control outcome analysis which examined the rates of lung cancer and alcoholic liver disease.

Given that lung cancer often relates to smoking and people who smoke are more likely to have mental health conditions, these disease outcomes served as a “rough proxy” for potential underlying mental health conditions, Miller explained.

But the investigators found “no difference whatsoever” between the two cohorts, and concluded that the findings were likely not confounded by not accounting for differences in mental health conditions.

“It’s hard to think of what underlying mental health condition would only affect the risk of dying by guns and not have any effect on the risk of dying by other methods,” Miller added.

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