Patient safety: Identifying all inpatient injuries not present-on-admission

Background: Injuries occurring during a hospitalization, such as patient falls or procedural trauma, are potentially important patient safety events. However, until recently, they have been difficult to enumerate at the population level. Basic descriptive data on the occurrence of inpatient injuries are needed to provide the context for prevention programs. The purpose of this study is to enumerate and describe the range of inpatient injuries in two states.

Method: We examined all hospital discharges, excluding newborns and deliveries (23 million) from the Healthcare Cost and Utilization Project 2003-2006 State Inpatient Databases for California and New York. Using all ICD-9-CM injury diagnosis codes (800-999) and the present-on-admission indicator, we identified incident inpatient injuries among non-delivery hospital discharges. A clinical expert panel was asked to identify injuries unlikely to have occurred during the hospitalization; these were excluded. E-codes were also examined to identify the cause of the injury. We conducted descriptive analyses (frequencies and cross-tabulations) of inpatient injuries by patient subgroups and by types of injuries.

Results: Inpatient injuries not present-on-admission were identified in 2.4% of non-delivery hospital discharges in California and New York over the four-year period. This results in an average of 138,000 inpatient injuries annually in these two states. Rates were higher among those 65 years of age and older than younger adults (3.4% vs. 2.3%) Rates were similar by gender, but varied by race/ethnicity, with rates highest among whites (2.7%) and lowest among Hispanics (1.2%). Most injuries not present on admission (86.4%) were coded as complications of medical care or devices. The remaining inpatient injuries (13.6%) comprised injuries from other external causes (4.8%), superficial injuries (2.4%) and open wounds (2.0%), as well as Medicare-defined patient falls and trauma – fractures (1.6%), crushing (1.0%), intracranial injury (0.2%) and burns (0.2%).

Conclusions: A substantial number of hospital discharges in California and New York involve an inpatient injury annually. Complications of care were the most common inpatient injuries, followed by traumatic injuries, including some injuries that are not monitored as part of Medicare-defined categories of hospital-acquired falls and trauma. Next steps include estimating national rates, assessing variation across states and hospitals, and evaluating impact of these injuries on lengths of stay. These analyses would help policy-makers, hospitals and clinicians to identify and implement opportunities for prevention and improving patient safety.