(CNN) - America's gun violence problem is evident nationwide, but a new study reveals that how different groups of people across the country experience such violence can vary dramatically, depending upon who they are and where they live.
The research, published in the Annals of Internal Medicine on Monday, measures drastic differences in how black and white men experience fatal gun violence in the United States.
Between 2008 and 2016, black men were more likely to die by guns in homicides, whereas white men were more likely to die by guns in suicides, and for both groups, the rates of those types of death varied widely by state, according to the study.
"The important thing here is that we were able to estimate these differences between black and white men, and that helps us understand health inequalities," said Corinne Riddell, a postdoctoral researcher at McGill University in Canada who was lead author of the study.
"I would hope that the findings bring awareness to how different the risks of firearm homicide and suicide are to black and white men, and I hope that the public will question the status quo and challenge some of the rhetoric around homicide and suicide deaths," she said. "These deaths are preventable, and this is evidenced by the different rates of homicide and suicide across states."
Biggest surprise: State differences
The study involved death-certificate data on homicides and suicides among non-Hispanic black and white men across the United States between 2008 and 2016. The data came from the Centers for Disease Control and Prevention's Wide-ranging Online Data for Epidemiologic Research database.
The researchers computed the average annual death rate among the men according to race, intent (such as homicide or suicide) and firearm involvement. They also calculated any inequalities in those age-adjusted rates between the two groups. In total, their analysis included 84,113 homicides and 251,772 suicides.
Compared with white men, the researchers found that black men experienced 27 more firearm homicides per 100,000 people annually nationwide (29.12 for black men vs. 2.1 for white men). The states with the highest rates of firearm homicide among black men in the data -- namely Missouri, Michigan, Illinois and Indiana -- also had the largest disparities between blacks and whites, the researchers found.
Suicide rates were found to be higher among white men than black men. Compared with black men, the researchers found that white men had nine more firearm suicides per 100,000 people annually nationwide (5.41 for black men vs. 14.34 for white men).
Six of the 10 states with the largest disparities in firearm suicide rates were in the southern part of the country: Mississippi, Arkansas, Alabama, Texas, South Carolina and Louisiana, the researchers found. The other four were in the West: Nevada, Arizona, New Mexico and Colorado.
"The most surprising thing to me when I was conducting the analysis was how different the rates were across states," Riddell said.
"We knew going into it that whites would have a higher rate of suicide and that black men would have a higher rate of homicide, but to see that level of variation in the rates across states was surprising," she said. "Any time I see variations so large like that, that can't be due to chance. I want to know why the differences exist."
The researchers also examined the relationships between gun ownership and these homicide and suicide rates by race and state. They used 2004 data, the most recent available, on household firearm ownership in the US from the CDC's national Behavioral Risk Factor Surveillance System.
They found that rates of gun ownership in a state were positively associated with both homicide and suicide rates among white men but only modestly associated with homicide and suicide rates among black men.
Some studies have found that black and white Americans hold opposing attitudes about gun ownership and knowing someone who has been harmed by guns.
A Pew Research Center report published last year found that 48% of white men say they currently own a gun, compared with 24% each of white women and non-white men, and only 16% of non-white women.
According to that report, 57% of black adults said they knew someone who has been shot, compared with 43% of whites and 42% of Hispanics. Also, the report found that 32% of blacks said they or someone in their family had been threatened or intimated by someone with a gun, compared with 20% of whites and 24% of Hispanics.
More research is needed to answer 'why'
Though the new study adds to the growing conversation about guns in the United States, it also had some limitations.
"The biggest limitation is that in our study, we only looked at fatalities, but non-fatal gun injuries make up a large proportion of the total burden of gun-related injury," Riddell said.
"When we're talking about firearm suicide attempts, they're about 80% to 90% fatal," she said. But for firearm attempted homicides, "they're closer to being 20% fatal. So in our study, we're missing most of the burden of firearm injuries associated with attempted homicide."
Other limitations include that the study focused on death certificates, which sometimes can be misclassified; only data on non-Hispanic black and white men were analyzed, which means more research is needed to determine whether similar findings would emerge among other groups; and the data on gun ownership were outdated, as they came from 2004, years before the other data in the study.
"The study uses national vital statistics, data from death certificates, to compare rates of firearm-related homicide and suicide deaths between black and white men by state. The strengths and limits of this investigation reflect the inherent strengths and limits of death certificates for this type of work," said Dr. James Buehler, clinical professor of health management and policy at Drexel University Dornsife School of Public Health in Philadelphia, who was not involved in the study but has researched health disparities in America.
"The limits of death certificates are that they do not provide much contextual information about the circumstances of people's lives in general or the circumstances surrounding their deaths in particular," Buehler said.
"This study, like any study that depends on death certificate data, paints a broad picture. It lets you see large patterns and make general inferences when the findings are triangulated with what is known from other research, and it lets you frame questions for further investigations," he said. "But this type of study generally cannot answer questions that begin with the word 'why.' "
Even though the study couldn't explain why there were these differences in gun deaths by race and states, the researchers offered some ideas.
The firearm suicides appeared to occur at the highest rates in rural settings while the homicides occurred at the highest rates in urban settings, the researchers noted.
This urban-rural divide could suggest that social and geographic isolation, having access to lethal mechanisms and stresses related to agricultural work play a role in high suicide rates among white men in rural areas. Higher levels of income inequality and crowding, among other factors, in metropolitan areas could play a role in high homicide rates among black men in urban areas, the researchers wrote in the study.
How to reduce disparities
Though not noted in the study, other factors known to cause health disparities between groups include social determinants, or the conditions in which people are born, grow, live, work and age, according to the CDC. Such determinants include sociological life differences, socioeconomic status, and access to and utilization of adequate health care.
"The large difference in homicide and suicide rates across states suggest that rates of homicide and suicide can be reduced by focusing on states with very high rates and learning from the states with the lowest rates. So there's more work to be done," Riddell said.
"To reduce disparities, it's important to know what types of deaths are reduced by a particular policy. For example, policies that focus on background checks for mental health or on safe storage of firearms may be effective at reducing firearm suicide more than firearm homicide," she added. "Reducing these suicides is a worthy pursuit, but it is also important to implement changes that are linked to reductions in firearm homicide in order to reduce racial inequalities and gun deaths overall."
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