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Epidemiologic Reviews
Focuses On The Science Related To Guns
We Have Learned
Useful But Still Only Limited Information Because Of Congressional
Threats
A striking conclusion from a special issue of
Epidemiologic Reviews devoted to examining the science on gun violence
is that there is too little science to begin with. So says Michel
Ibrahim, Johns Hopkins epidemiologist and co-editor of the
violence issue. According to Ibrahim, “epidemiologic research on gun
violence is scarce, especially research with powerful study designs
such as prospective cohort studies. Several papers in the issue [of
Epidemiologic Reviews] addressed violence generally and attempted to
extrapolate to gun violence. “
Evidence Shortfall
A frequently cited reason for the shortage is the
belief that Congress has mandated against it. But according to
Daniel Webster, a second co-editor of the special issue and
Director of the Hopkins Center for Gun Policy and Research, “ … it is
not accurate to say that there has been a ban on federally funded
research on gun violence. There is no piece of legislation that says
that these agencies can’t use their funds designated for broad
categories (e.g., youth violence, domestic violence, gang violence,
substance abuse and violence) to support research that examines guns
and gun violence. The
National
Institute of Justice and to a much lesser degree the CDC and NIH have
funded research studies on gun violence during the past 20 years. But
these agencies have, for the most part, decided to avoid
funding
any study
that has the potential
to offend the gun lobby in order to avoid budget cuts that members of
Congress threaten if they don’t like the research or the findings. It
was the efforts to cut the budget of the CDC and, initially, to
completely eliminate its Center for Injury Prevention and Control,
that has led to restricted (both in $ and research question) funding.”
Staggering Toll
"There is widespread concern about the staggering toll of gun violence
in the U.S.,
according to Ibrahim.
In
the year 2013 alone, firearms were responsible for 11,208 deaths by
homicide (3.5 per 100,000 citizens). While homicides by firearm occur
less frequently in the US than, for example, in Columbia (38.1 per
100,000 citizens), many are surprised to find that they are on par
with countries such as Nicaragua (34.86 per 100,000 citizens),
Palestine (3.09 per 100,000 citizens) and Uganda (3.71 per 100,000
citizens). These numbers also don’t account for non-lethal firearm
induced trauma, both mental and physical, and the 21,175 suicide
deaths by firearm (6.7 per 100,000 citizens).
Gun
Access & Suicide
An important topic addressed in one of the articles is
the relationship between firearm access and suicide rates. Is this
relationship causal or the result of a confounder? Using a bias
analysis, the authors of the article determine that a “confounder
would need to possess an untenable combination of characteristics,
such as being not only 1) as potent a suicide risk factor as the
psychiatric disorders most tightly linked to suicide (e.g., major
depressive and substance use disorders) but also 2) an order of
magnitude more imbalanced across households with versus without
firearms than is any known risk factor.” As such, they believe it is
highly unlikely that such a confounder exists and has gone undetected
to date. Thus firearm accessibility alone is likely the cause of
increased suicide rates in homes where firearms are kept.
Substance Abuse
Three of the articles examine the relationship between
substance use and gun-related behaviors. A causal relationship between
substance abuse and gun violence has long been assumed and a federal
law prohibits the purchase of firearms by those that unlawfully use or
are addicted to illegal substances. However, defining individuals to
exempt from gun purchasing under this definition is still a gray area
due to the presence of confounders. For example, positive associations
between substance use and gun violence disappear or decrease when data
is adjusted for psychiatric disorders. That said, interventions can be
effective even without complete understanding of the causal
relationship. It remains that drug selling and firearm usage are
positively correlated, so limiting firearm access for drug sellers may
have positive outcomes even if the underlying cause is rooted in
psychiatric disorders which, consequently, are much more difficult to
identify.
Social
Networks
Another interesting review showed that the likelihood
of gun victimization or perpetration is predicted by social network
distance from individuals who use guns. The review demonstrated the
potential of social network analysis to predict gun violence and guide
prevention efforts.
Impact
of Interventions
Studies reviewed in the issue show that the
effectiveness of firearm safety screening and counseling can be
achieved through clinician training and that patients and families are
accepting of such counseling, however the authors reviewing the
material believe that higher quality studies are needed. Additionally,
another article demonstrates that counseling and device provision
successfully encourage the safe storage of firearms. Lastly, the final
article in the issue tackles a characterization of the global effects
of gun laws in a review of 130 studies carried out in 10 different
countries between 1950 and 2014. The authors believe that, “high
quality research on the association between the implementation or
repeal of firearm legislation (rather than the evaluation of existing
laws) and firearm injuries would lead to a better understanding of
what interventions are likely to work given local contexts.”
Editor’s Overall Take
According to Ibrahim, “several of the studies reviewed
used ecological, cross-sectional, and before-after designs, which,
because of the inherent confounding factors, limited the degree of
certainty and generalizability of the results. In spite of these
limitations, the weight of the evidence points to plausible
relationships between guns access and suicide, between deviant social
networks and gun violence, and between restrictive gun legislation and
reduced deaths. Better designed epidemiologic studies would provide
more firm conclusions.” He added “the strongest evidence of benefit
comes from reviews (some used randomized trials) about clinicians’
practices that encourage safe gun behaviors that were shown to be
effective strategies.”
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