Average annual direct medical costs for hospital-admitted firearm injuries exceeded $622 million for the years of 2003 through 2013. This is an underestimate of the overall direct hospitalization costs because readmissions for further treatment may not have been identified with an Ecode noting the original cause of the injury. While this represents less than 1% of the overall costs of $377 billion for all hospital stays in the US, firearm injuries represent relatively high costs per patient (Moore et al., 2014). In 2012, the average cost per hospital stay was $10,400 (Moore et al., 2014), which is less than half of the average costs for a firearm injury. The lowest average cost for a firearm-related admission was $16,975 for an unintentional firearm injury, and the highest were $32,237 for an injury from an assault weapon and $33,462 from legal intervention.

In 2012, uninsured patients comprised 5% of all hospitalizations, while we found that from 2003 to 2013, an average of 30.1% of firearm injury hospitalizations were among the uninsured (Moore et al., 2014). In contrast, 29% of all hospitalizations were paid by private insurance compared with 21% of firearm hospitalizations. Based on their per-hospital cost, the overall hospitalization cost, and the low proportion of private insurance coverage, firearm injuries pose a high burden on our healthcare system.

Our cost estimates provide only a small component of the overall burden of firearm injuries. Studies reporting lifetime medical and productivity costs range from $48 to $175 billion (Corso et al., 2007; Lee et al., 2014; Miller, 2012; Fowler et al., 2015; Allareddy et al., 2012), with differences based on the source of firearm incidence data, types of firearm injuries included, sources of cost estimates, and types of costs included in the estimate. Lost productivity from premature death as well as work time loss was the largest component of these costs, with a smaller proportion from direct medical care.

Studies that focus on medical care also exhibit substantial variation in methods and estimated cost burden. Four studies report the lifetime medical care costs from firearm injuries that occur in 1 year, and these range from an average cost of $684 million for hospital admissions in 2000 (Fowler et al., 2015) to an average cost of $1.5 billion for hospital admissions in 2010 (Miller, 2012). These studies vary in their definition of medical care costs, but most cover all costs, including transport, readmission, and nursing care, and some estimate lifetime rather than annual costs (Corso et al., 2007; Lee et al., 2014; Miller, 2012; Fowler et al., 2015; Allareddy et al., 2012).

The two main sources for estimating non-fatal firearm injuries are the National Inpatient Sample, used here, and the Consumer Product Safety Commission’s National Electronic Injury Surveillance System – All Injury Program, which estimates national firearm injury hospitalization rates based on 66 hospital Emergency Departments (Schroeder & Ault, 2001; U.S. Consumer Product Safety Commission, 2000). Although these hospitals are chosen to represent a range of hospitals by size, the sample over-represents urban emergency departments. Estimates of firearm injuries from the National Inpatient Sample tend to be lower than those from the National Electronic Injury Surveillance System. For example, Lee et al., used the National Inpatient Sample to estimate an annual average of 28,249 hospital admissions from 2006 through 2010, and in comparison Fowler et al., estimated an average of 36,224 per year from 2010 through 2012. Our annual average of 30,617 was closer to other estimates from the National Inpatient Sample.

We found that firearm injuries disproportionately affect youth, males, and a non-White population. These trends have been widely reported in previous research (Fowler et al., 2015; Allareddy et al., 2012; Leventhal et al., 2014). In addition, we found that assaults caused more than 60% of admissions, followed by unintentional injuries. These trends are also similar to those reported in other studies of non-fatal firearm injuries (Fowler et al., 2015; Leventhal et al., 2014). However, because firearms are such a lethal means of suicide, suicide comprises a higher proportion of firearm mortality by intent (Fowler et al., 2015). Rates of firearm hospital admissions did not change significantly from 2003 through 2013. Previous studies have found that hospitalizations decreased between 1998 and 2011 among children injured by a firearm (Kalesan et al., 2016), and for all firearm hospitalizations from 2000 to 2010 (Kalesan et al., 2013).

Handguns and assaults posed the largest overall hospitalization cost burden. Although the highest per-hospital cost was for assault weapons, handguns comprised over 70% of firearm injuries among those for which the weapon type was known and the total annual hospitalization costs were nearly $183 million. Assaults had the third-highest cost per hospitalization and were the most frequent intent, costing an annual total of nearly $373 million. Two other studies reported costs by injury intent. Fowler et al. reported lifetime medical and lost work time costs among those admitted to a hospital to be approximately $475 million for unintentional firearm injuries, $600 million for self-harm/suicide, and over $2 billion for assault/homicide (Fowler et al., 2015). Corso et al. reported the lifetime costs medical costs for assaults as $800 million and for self-harm as $124 million (this study included only violent firearm injuries) (Corso et al., 2007). While these study’s estimates are higher due to factors described above, the trends by intent are similar.

No prior studies have reported costs associated with the type of firearm, although information about the type of firearm would be helpful to prioritize intervention approaches. One major challenge to estimating costs by firearm type is the high prevalence of hospitalizations for which the firearm type is unknown. In the National Inpatient Sample, nearly 60% of the firearm types were unknown. Handguns accounted for nearly 70% of all hospitalizations for which weapon type was known, and among these handguns accounted for four times the total annual hospitalization costs than for any other type of firearm.

In addition to a high prevalence of missing information about firearm type, this study has other limitations. Approximately 25% of injuries in the National Inpatient Sample are missing Ecodes, and it is possible that these could contain some firearm injuries. Our examination of injury diagnoses among admissions without Ecodes suggested that firearm injuries likely comprise less than 1% of those missing Ecodes. Our sample also does not include readmissions that did not have an Ecode identifying a firearm as the cause of injury, and thus our findings are likely an underestimate. The extent of missing data for the type of firearm limits our ability to fully examine injury and cost characteristics. The NIS is the largest and most representative sample of US hospitalizations, but may be subject to sampling bias and not designed specifically as a firearm injury surveillance system. Our analysis includes only hospitalized firearm injuries, which are about one third of all reported firearm injuries.