The decision to buy a handgun for the first time is typically motivated by self-protection. But it also raises the purchasers’ risk of deliberately shooting themselves by ninefold on average, with the danger most acute in the weeks after purchase, scientists reported on Wednesday. The risk remains elevated for years, they said.
The findings are from the largest analysis to date tracking individual, first-time gun owners and suicide for more than a decade.
The study, posted by The New England Journal of Medicine, does not greatly alter the prevailing understanding of suicide risk linked to gun ownership. Previous research had suggested a similarly increased risk, due largely to the ease of having such a lethal option at hand.
But experts said the new evidence was more powerfully persuasive than any research to date. The study tracked nearly 700,000 first-time handgun buyers, year by year, and compared them with similar non-owners, breaking out risk by gender. Men who bought a gun for the first time were eight times as likely to kill themselves by gunshot in the subsequent 12 years than non-owners; women were 35 times as likely to do so. (Male gun owners far outnumbered women owners in the study.)
“I find the work extremely compelling,” said Amy Street, a research psychologist at the National Center for PTSD, VA Boston Healthcare System and Boston University School of Medicine. Dr. Street did not contribute to the study, which was led by David Studdert, a professor of medicine and law at Stanford.
“We know women make more attempts than men, but they use less lethal means,” Dr. Street added. “It makes sense: When women start using lethal means, you’re going to see this dramatic jump in rates.”
Historically, public health research on firearms has been limited by privacy issues and political opposition. Most previous studies were retrospective: post-mortem analyses of suicides that relied on incomplete information about gun owners and, for comparison, non-owners.
Dr. Studdert’s study, which looked at deaths and gun ownership in California, overcame these obstacles. By California law, all legal gun sales must go through licensed dealers and be reported to the state’s Department of Justice. The department archives each transaction and includes more detail on the purchase than most any other state.
The research team integrated this information with two other sources: a California log of deaths determined to be suicides, which all states track to some degree; and voter rolls, which include about 60 percent of adults in the state, or 26.3 million adults.
By linking gun purchases to the voter registry and suicide data, the team was able to track individuals over time, from October 2004 to December 2016. The researchers checked gun purchases back to 1985 to make sure that individuals in the study were in fact first-time buyers. They also reclassified those who later sold their weapons as non-owners.
This left 676,425 people who bought their first gun during the 12-year period and kept it. The weapons were predominantly handguns, which are the method of choice in about three-quarters of suicides by firearm. California did not begin collecting data on rifles and shotguns until 2014.
The team tallied the suicides among new owners and non-owners, matched by age, gender and other similarities, and tested for a series of alternate possibilities, like whether owners were as likely to kill themselves by other means. They were not.
Another possibility was so-called reverse causation: that many buyers were bent on suicide before they bought the gun. The findings did provide some evidence of that. In the month immediately after first-time owners obtained their weapons (California has a 10-day waiting period), the risk of shooting themselves on purpose was nearly 500 per 100,000, about 100 times higher than similar non-owners; after several years it tapered off to about twice the rate.
“We sure do see evidence that people went to get the gun because they had planned to take their own lives,” Dr. Studdert said.
The risk of suicide remained elevated over the entire 12-year duration of the study, and it was in this longer period after the first month that most of the suicides — 52 percent — occurred. “During this period, the gun acts much more like an ambient risk — it’s always there,” Dr. Studdert said.
The majority of people who attempt suicide do not die; attempts outnumber completed acts by about eight to one. Those who do make an attempt are at greater risk of trying again later, compared with those who have not, studies have found. Still, less than 10 percent of those who make an attempt will subsequently go on to complete the act, said Dr. Matthew Miller, a professor of health sciences and epidemiology at Northeastern University and an author on the study.
“Many suicide attempts are impulsive, and the crisis that leads to them is fleeting,” Dr. Miller said. “The method you use largely determines whether you live or die. And if you use a gun, you are far more likely to die than with other methods, like taking pills. With guns, you usually do not get a second chance.”
Other authors on the study included scientists at the University of California, Davis; Erasmus University in Rotterdam, in the Netherlands; and the University of Melbourne, in Australia. It was financed by the Fund for a Safer Future and the Joyce Foundation, both of which have supported research on gun ownership, and by Stanford.
As rigorous as the findings are, they are not likely to move most gun-rights proponents, who emphasize the idea that people need guns for protection.
The study did not examine owners’ detailed information like medical histories or personal circumstances — such as living alone — that could have shown they were at greater risk for suicide. But most risk factors for suicide, like persistent mental distress and drug use, tend not to differ much between gun owners and non-owners, previous studies have found. Any unseen factor that could account for the findings would have to raise suicide risk by 10 times in owners, compared with non-owners, and there were no such candidates, the authors of the new study said.
“They really questioned their own results and tested many alternate hypotheses to account for their results,” Dr. Street said. “To me, this makes the findings more compelling still.”