When gun enthusiasts gather for the National Rifle Association’s annual conventions, rates of gun-related injuries and deaths drop by 20 percent nationwide—and a whopping 63 percent in the hosting state—according to an analysis published this week in the New England Journal of Medicine.

The finding was based on an analysis of insurance data on gun injury rates during NRA conventions from 2007 through 2015, as well as rates three weeks before and three weeks after each of the conventions. The researchers behind the work—health policy expert Anupam Jena, MD, PhD of Harvard Medical School and economist Andrew Olenski of Columbia University—also looked at crime rates during those times.

They found no significant change in crime rates despite the dip in injuries. They also noted that the largest drops in firearm-related injuries during NRA conventions were in men, the southern and western areas of the country, and in states with the highest levels of gun ownership.

Though the analysis can only provide a correlation—not causation—Jena and Olenski suggest it may refute a common argument among gun proponents. That is, that gun accidents happen primarily in the hands of inexperienced users and that practice and training—promoted by the NRA—can greatly reduce or eliminate safety concerns and accidents, which affect thousands each year. In 2014, for example, there were 461 unintentional firearm deaths and 15,928 unintentional, non-fatal injuries, 1,960 of which involved youths.

In their analysis, Jena and Olenski concluded that the findings:

“...are consistent with reductions in firearm injuries occurring as a result of lower rates of firearm use during the brief period when many firearm owners and owners of places where firearms are used may be attending an NRA convention. Our results suggest that firearm-safety concerns and risks of injury are relevant even among experienced gun owners.”

In a statement to CNN, NRA's director of public affairs, Jennifer Baker, called the study “absurd.” She continued: "This study is another example of when data and numbers fly in the face of logic and common sense.”

Baker went on to note that only a small fraction of the country’s gun owners—a group that totals about a third of Americans—attend the NRA’s annual conventions. She questioned how such a relatively small number of gun owners could explain such large decreases in injuries.

In a response to CNN, co-author Jena emphasized that the study was not designed to explain the cause of the drops. But he speculated that gun owners who attend NRA conventions may be those who tend to use their guns more frequently than non-attending owners.

Moreover, he and Olenski noted a potential domino effect from the convention disrupting other group events or trips involving firearms and venues, such as shooting ranges and hunting grounds, where owners may temporarily close up to attend the convention. Last, the researchers noted that many NRA convention goers travel long distances to attend, potentially helping to explain the nationwide declines. For instance, 60 percent of the 81,000 NRA members attending the 2017 convention ventured more than 200 miles to get there.

Other researchers were accepting of the analysis and its conclusions. Stephen Hargarten, chairman of emergency medicine at the Medical College of Wisconsin in Milwaukee, was not involved in the study and told Reuters that it “passes the sniff test.” Hargarten added that “it makes sense that decreased exposure and decreased usage would result in fewer events.”

Nationally, the study found that baseline injury rates dropped from 1.5 per 100,000 people during control periods to 1.2 per 100,000 during NRA conventions. It also found that declines in injuries were larger within hosting states, dropping from 1.9 per 100,000 to 0.7 per 100,000 during the conventions. The conventions included in the study from 2015 back to 2001 were held in: Nashville, Indianapolis, Houston, St. Louis, Pittsburgh, Charlotte, Phoenix, Louisville, and St. Louis.

NEJM, 2018. DOI: 10.1056/NEJMc1712773 (About DOIs).