Primecuts -This Week in the Journals

March 6, 2018

By Katharine Lawrence, MD

Peer Reviewed

On February 14th, 2018, Nikolas Cruz, a nineteen-year-old ex-high school student at Marjory Stoneman Douglas High School in Parkland, Florida, opened fire on his classmates and teachers, killing 17 and wounding many others. It was the deadliest school shooting in United States’ since the Sandy Hook tragedy in 2012; it was also the 6th school shooting incident of 2018, and the 17th incident of gunfire in schools. Cruz used an AR-15-style assault rifle, legally purchased from a gun shop in South Florida. He was reported to own at least seven other guns, mostly long guns.

In response to the tragedy, politicians and community organizers have again taken up the call for responsible firearm legislation. The teenagers who survived the shooting traveled to Washington DC to call on political leaders to enact changes in gun control policies, in a powerful showing of student organization. Major corporations have also taken a stand on the issue. Dick’s Sporting Goods announced that it would immediately end its sales of assault-style rifles in stores, and would require purchasers of any gun to be 21 years of age. Walmart (which stopped selling high-powered rifles in 2015), similarly raised its buying age for guns, and pledged to remove all items resembling assault-style rifles, including toys and airguns, from its shelves. Other companies are ending discounts extended to National Rifle Association (NRA) members, in response partially to social pressures from consumers.

In acknowledgement of the tragedy, and the important role of physicians in contributing to national dialogue on the issue of responsible firearm legislation, here are the PrimeCuts for this week:


Firearm Laws and Firearm Homicides: A Systematic Review (2017)

Firearm homicide is a leading cause of injury death in the United States; however, there is considerable debate over the effectiveness of firearm policies. To address this, researchers at Harvard conducted a systematic review of peer-reviewed articles from 1970-2016 focusing on the association between US firearm laws and firearm homicide. Firearm laws were divided in five categories, addressing gun trafficking, background checks, child safety, military-style assault weapons bans, and restrictions on firearms in public places. Studies were assessed using standardized guides and quality metrics for robustness and bias.

Ultimately, the researchers identified 34 studies, including narrative reviews, addressing the topics of interest. All 34 were ecological studies; 21 were from medical journals, with the rest being from social science and legal journals. Most were rated as ‘fair’ quality. Twelve studies addressed strengthening background checks, with the overall evidence supporting the conclusion that strengthening background checks and permit processes are associated with decreased firearm homicides. The remaining studies (17 addressing firearm trafficking, 9 on improving child safety, 4 on banning of military-style assault weapons) were not associated with changes in firearm homicide rates. The evidence from 15 studies on restricting guns in public places and leniency in gun carrying was mixed.

The authors ultimately concluded that, in the aggregate, stronger gun policies were associated with decreased rates of firearm homicide, even after adjusting for demographic and sociologic factors. Laws that specifically strengthened background checks and permit-to-purchase seemed to decrease firearm homicide

rates. Limitations of the review include the selective use of peer-reviewed journals, which did not include a number of legal journals. The authors also note a continued need for high-quality research to further address and clarify these topics.

Evaluating the Impact of Florida’s “Stand Your Ground” Self-defense Law on Homicide and Suicide by Firearm: An Interrupted Time Series Study (2017)

In 2005, Florida amended its self-defense laws to provide legal immunity to individuals using lethal force in self-defense, known as the ‘stand your ground’ laws. Using an interrupted time series, researchers from the UK reviewed data from the Wide-ranging Online Data for Epidemiologic Research (WONDER) web portal at the CDC to estimate the impact of Florida’s stand your ground law on rates of homicide. The main outcomes of the study were monthly rates of all-cause homicide and firearm-related homicide. The study also looked at control outcomes of all-cause suicide, and suicide by firearm, as well as outcomes in comparison states without stand your ground laws (New York, New Jersey, Ohio, and Virginia).

Results showed that, prior to the stand your ground law (1999-2004), the mean monthly homicide rate in Florida was 0.49 deaths per 100 000 (average 81.93 cases), and the rate of homicide by firearm was 0.29 deaths per 100 000 (49.06 cases), with firearm homicides accounting for over 50% of all-cause homicides. Both rates had an underlying trend of 0.1% decrease per month. After implementation of the stand your ground laws, there was an ‘abrupt and sustained’ increase in both the monthly homicide rate of 24.4% (relative risk [RR] 1.24; 95% CI,1.16-1.33) and in the rate of homicide by firearm of 31.6% (RR 1.32; 95% CI 1.21-1.44). No evidence of change was found in the analyses of comparison states for either homicide or homicide by firearm, and no changes were observed in control outcomes such as suicide in Florida.

Researchers concluded that the implementation of Florida’s stand your ground ruling was associated with a significant increase in homicides and homicides by firearm but no change in rates of suicide or suicide by firearm. Limitations of the study included unidentified confounders and circumstances unique to Florida that were not accounted for, as well as limitations in documentation of mortality data. Commentary following the study questioned the study’s failure to differentiate between unlawful homicides and those considered ‘justifiable’ under the new laws. A subsequent inquiry by the authors found that both lawful and unlawful homicides increased, with unlawful accounting for most of the increase. 

Association Between Gun Law Reforms and Intentional Firearm Deaths in Australia, 1979-2013 (2016)

In 1996 Australia introduced major gun law reforms that included a ban on semiautomatic rifles, pump-action shotguns and rifles, and the initiation of a program for buyback of firearms. The legislation was in response to a massacre in which a man used 2 semi-automatic rifles to kill 35 people. In an observational study using data from the National Injury Surveillance Unit (Australian Bureau of Statisics) and ICD-9 codes, researchers in the country aimed to assess the impact of the legislation on the incidence of mass firearm homicides and total firearm deaths between 1979 and 2013. Outcomes evaluated included all-cause homicide, firearm homicide, all-cause suicide, and firearm-related suicide.

They found that the mean rate of total firearm deaths prior to 1996 was 3.6 (95%CI, 3.3-3.9) per 100,000 population (average decline of 3% per year), whereas from 1997-2013 the mean rate of total firearm deaths was 1.2 (95% CI 1.0-1.4) per 100000 population (average decline of 4.9% per year). The mean annual rate of firearm homicide prior to 1996 was 0.57 (95%CI, 0.51-0.63) per 100000 population; this rate declined to 0.20 (95% CI 0.17-0.25) per 100000, representing an accelerated decline in deaths from 3% to 5.5% per year. While this change in decline was not statistically significant, the authors did find a statistically significant acceleration in the preexisting downward trend for firearm suicide. The authors also noted that, while there were 13 fatal mass shootings (described as >5 victims) prior to 1996, there were none after legislation implementations.

The study concluded that there was a more rapid decline in firearm deaths between 1997 and 2013 compared with before 1997, as well as a decline in total non-firearm suicide and homicide deaths of a greater magnitude. Because of this overall downward trend, however, they determined it was not possible to determine whether the change in firearm deaths could be attributed to the gun law reforms. Limitations of the study include the inability of observational studies to determine causality, and the exclusion of accidental deaths from analysis, as well as the overall considerably smaller data size (when compared to firearm morbidity and mortality in countries like the United States).

Reductions In Firearm-Related Mortality And Hospitalizations In Brazil After Gun Control (2007) (NOTE: this article is from a 2007 publication).

Brazil is known for having one of the world’s highest homicide rates, with as many as 45,000 people murdered each year. Homicide represents the leading cause of death for men aged 15-44, and 90% of homicides in this age group involved firearms. In 2003, the Brazilian government enacted legislation on gun control, instituting background checks, gun registration, and minimum age purchases, as well as stricter fines and prison sentences for gun violations. In 2007, researchers from the University of Sao Paulo investigated the relationship between gun-related mortality and firearm legislation. From data collected in the Brazilian Ministry of Health’s vital statistics and ICD-10 codes, the team used a linear time-series regression model to analyze and estimate rates of firearm-related mortality and firearm-related hospitalizations in Brazil’s 27 federal districts between 1996-2004.

They found that, prior to 2004, rates of firearm homicides increased, whereas in 2004 rates actually decreased by 8.2%, an observed rate 15.4% lower than predicted. In that same year, all but one district showed a decline in firearm homicides (ranging from 2.1 to 20.1%), and all but six areas showed statistically significantly lower-than-predicted values. Researchers also noted a 4.6% decline in firearm-related hospitalizations from 2003-2004, largely due to decreased admissions for unintentional injuries and attempted suicides. Of note, some parts of Brazil did not see a decrease in firearm-related mortality, notably in sparsely populated areas and areas of historically poor law enforcement.

The study concluded that ‘a good portion of recent declines in firearm-related deaths and hospitalizations could reasonably be attributed to new government measures aimed at reducing the availability of guns’. They suggest that as many as 5,563 deaths in 2004 may have been averted by the legislation. Limitations of the study included the observational nature, confounders such as recent economic improvements in the country, and the demographic heterogeneity of the study population. Confidence intervals and other measures of statistical significance were not presented in the paper.


Emergency Department Visits For Firearm-Related Injuries In The United States, 2006–14 (2017)

In a retrospective study, researchers from Johns Hopkins used data from the Nationwide Emergency Department Sample of Healthcare Cost and Utilization Project to quantify the clinical and financial burden associated with ED visits for firearm-related injuries. They identified over 150 thousand patients in the database (translating to over 700 thousand patients nationally), representing an annual financial burden of approximately $2.8 billion in ED and inpatient charges.

State Intimate Partner Violence (IPV) Related Firearm Laws and Intimate Partner Homicide Rates in the United States, 1991 to 2015 (2017)

Intimate partner homicide (IPH) accounts for 50% of all homicides involving women in the United States, with approximately 50% of those homicides perpetuated by firearms. To address this, some states have adopted laws restricting firearm possession by offenders. This study looked at the association between state IPV-related firearm laws and IPH rates over a 25-year period. It found that states that prohibit persons subject to IPV-related restraining orders from possessing firearms and also require them to relinquish firearms in their possession were associated with a statistically significant 9.7% lower total IPH rates and 14.0% lower firearm-related IPH rates than in states without these laws.

Funding and Publication of Research on Gun Violence and Other Leading Causes of Death (2017)

This study sought to evaluate the impact of a 1996 congressional appropriations bills that restricted the use of CDC funds for the advocacy or promotion of gun control. Using CDC mortality statistics and research funding data from the Federal RePORTER database, researchers found that, when compared to other leading causes of death, gun violence was associated with less funding (1.6% of predicted funding) and fewer publications (4.5% of predicted publication volume). Authors noted that, while gun violence kills about as many individuals as sepsis each year, funding for gun violence research was only 0.7% of that for sepsis.

Physician Speech and Firearm Safety Wollschlaeger v Governor, Florida (2017)

In 2017, the US Court of Appeals for the Eleventh Circuit struck down key provisions of a Florida law (the ‘gag law’) that prohibited physicians from speaking with their patients about firearm safety. In this article, authors discuss the history of the legislation, the case Wollschlaeger v Governor, Florida, and the implications of the ruling.

Dr. Katharine Lawrence is a 2nd year internal medicine resident at NYU Langone Health 

Peer reviewed by Amar Parikh, MD, Associate Editor of Clinical Correlations and Chief Resident of Internal Medicine at NYU Langone Health 

Image courtesy of NBC News.

Additional References:

Humphreys DK, Gasparrini A, Wiebe DJ. Association Between Enactment of a “Stand Your Ground” Self-defense Law and Unlawful Homicides in Florida. JAMA Intern Med. 2017;177(10):1523–1524. doi:10.1001/. jamainternmed.2017.3433