WASHINGTON, D.C. – U.S. Senators Chris Murphy (D-CT) and Richard Blumenthal (D-CT) joined U.S. Senator Bob Menendez (D-NJ) and a group of colleagues in sending a letter to the Secretary of Health and Human Services (HHS) Alex Azar, demanding answers to ensure the accuracy of the Centers for Disease Control and Prevention’s (CDC) firearm injury data. According to recent analysis by FiveThirtyEight and The Trace, the CDC’s most recent figures on non-fatal firearm injures fall short of the agency’s own standards, and should be treated as ‘unstable and potentially unreliable.’ Researchers, journalists, lawmakers, law enforcement, and the American public at large rely on the agency’s data.

“Given the wide scale reliance on the CDC’s numbers, it is imperative that the agency ensure its data is accurate and up to date,” wrote the Senators to Secretary Azar. “While we appreciate that the CDC is looking ‘into various ways to strengthen the estimates for nonfatal firearm injuries’, we respectfully request information regarding actions the agency is taking to remedy its data shortcomings.” 

According to FiveThirtyEight and The Trace, the CDC’s findings of a 37 percent increase in non-fatal gun injuries between 2015 and 2016 – the largest single-year increase recorded in more than 15 years – is out of step with a downward trend showed in data from multiple independent public health and criminal justice databases analyzed by the publications.

The Senators questioned the CDC’s reliance of firearm injury data collected by a smaller sample size of National Electronic Injury Surveillance System (NEISS) hospitals, when the Department of Health and Human Services (HHS) relies on the Healthcare Cost and Utilization database containing data from more than 950 participating hospitals.

“Given that the CDC is not currently conducting gun violence research, the very least the agency can do is to ensure that its gun injury numbers are accurate,” concluded the Senators before listing a series of specific questions to which the agency would be required to respond by April 20.  

The letter was also signed by U.S. Senators Cory Booker (D-NJ), Kirsten Gillibrand (D-NY), Angus King (I-ME), Mazie Hirono (D-HI), Amy Klobuchar (D-MN), Kamala Harris (D-CA), and Tina Smith (D-MN).    

The full text of the letter is available here and below.

Dear Secretary Azar:

We write regarding a recent article published in The Trace and FiveThirtyEight highlighting the unreliable nature of the Centers for Disease Control and Prevention’s (CDC) firearm injury data. Researchers, journalists, lawmakers, law enforcement, and the American public at large rely on the CDC’s data: “[s]ince 2010, at least 50 academic articles have cited the CDC’s gun injury estimates.” Yet, the CDC acknowledges that its national estimate of gun injuries is “unstable and potentially unreliable”. Given the wide scale reliance on the CDC’s numbers, it is imperative that the agency ensure its data is accurate and up to date. While we appreciate that the CDC is looking “into various ways to strengthen the estimates for nonfatal firearm injuries”, we respectfully request information regarding actions the agency is taking to remedy its data shortcomings. 

According to The Trace, the CDC’s gun injury confidence interval for 2017 is four times wider than the interval from 2001. Moreover, the coefficient variable, “a measure of an estimate’s uncertainty in which higher values indicate larger potential errors” rose from 22.1 percent in 2001 to 39.1 percent in 2017. A possible explanation for these increases could be due to the CDC sourcing its data from a small number of hospitals known as the National Electronic Injury Surveillance System (NEISS), a database maintained by the Consumer Product Safety Commission. The NEISS collects records from approximately 100 hospitals, and only 66 of those 100 hospitals collect data regarding gunshot injuries. In contrast, the Department of Health and Human Services uses the Healthcare Cost and Utilization Project database containing data from more than 950 hospitals. Moreover, the NEISS sample of hospitals fails to take into account regional differences in gunshot injuries. There appears to be no rational reason that the CDC and HHS use different databases. 

Given that the CDC is not currently conducting gun violence research, the very least the agency can do is to ensure that its gun injury numbers are accurate. To better understand the issue, we request responses to the following questions:

  1. What is the CDC doing to more accurately track non-fatal firearm injuries? Please be specific.
  2. What additional resources, if any, does the CDC need in order to better ensure more accurate firearm injury data?
  3. Why does the CDC use the NEISS database rather than the Healthcare Cost and Utilization Project database in order to track non-fatal firearm injuries? 
  4. What accounts for the four-fold increase in the CDC’s gun injury confidence interval between 2011 and 2017?
  5. As the confidence interval increased over the course of 16 years, did the CDC take any steps to ameliorate the problem? If so, please describe those steps. If not, please explain why no action was taken.
  6. What role has the Dickey Amendment played in the CDC’s decision to continue using NEISS even as the data proved less and less reliable? 
  7. Has the CDC received instructions from any executive branch officials pursuant to its non-fatal firearm injury data? If so, please describe any such instructions and communications. 

Thank you in advance for your cooperation. We look forward to receiving your responses by April 20, 2019.

###