External cause coding of injury encounters in the Military Health System among active component U.S. service members,...

Knowledge of injury causes is essential for prevention. To investigate cause coding in service members' electronic medical records, injury encounters from 2016 to 2019 containing at least 1 external cause code were analyzed. Approximately 10% of incident injury encounters contained at least 1 cause code describing the mechanism, activity, or place of occurrence. Less than 2% of overuse injury encounters had a cause code each year, compared to 36.4-44.0% of acute injuries occurring from 2016 to 2019. Cause coding occurred more frequently in records from military facilities compared to outsourced care (p<0.001). Inpatient records were more likely to be cause-coded than outpatient records (p<0.001). More injury encounters in emergency clinics were cause coded (>50%), compared to approximately 7% of primary care and 2% of specialist encounters. In 2019, the leading mechanism was overexertion (19.9%), followed by falls, slips, or trips (18.7%). The primary activity associated with injuries was running (21.1%). Military training ground was the leading place of occurrence (13.0%). Improvements to the quality and quantity of external cause coding in the medical records would provide critical details to inform military injury prevention. From 2016 through 2019, approximately 10% of 1.5 million annual U.S. service member incident injury medical encounters contained external cause codes. Acute injuries were approximately 20 times more likely to receive a cause code than overuse injuries. Causes were less likely to be recorded in outpatient care records and at non-military health care facilities.