Hospital admissions associated with traumatic brain injury in the US Army during peacetime: 1990s trends

This paper examines 10-year trends in traumatic brain injury (TBI)-related hospitalization rates for active duty US Army personnel in the 1990s. It does this within the context of various factors, including enhanced injury prevention policies and changed hospital admission practices, that may have affected TBI hospitalization rates. It also compares TBI hospitalization rates in the Army to those from an age-comparable segment of the US civilian population over this time period.

Crude (unadjusted) incidence rates for all active duty US Army personnel hospitalized with a TBI diagnosis from fiscal years (FY) 1990 to 1999 were calculated. Once the trends were identified, the percentage change in the overall rate, as well as the rates for different TBI severity levels, and in-hospital deaths from FY1990 and FY1999 were analyzed. Changes in age- and gender-specific rates as well as crude rates for cases with and without other injuries and cases treated in military and civilian hospitals were also analyzed. Rate ratios were used to compare aggregated 5-year TBI hospitalization rates in the Army to rates for civilians 17-49 years of age during the following time periods: 1990-1994 and 1995-1999. The rates used in the comparison were adjusted to control for differences in age and gender.

The overall incidence of TBI-related hospitalization in the Army decreased 75% from FY1990 to FY1999. The rates for all TBI severity levels decreased, but the rate for mild TBI decreased more than the rates for moderate and severe TBI. The rate of in-hospital deaths from TBI also decreased. Rates decreased similarly for males and females, across all age groups, as well as for cases with and without other injuries. TBI rates decreased for Army personnel treated in military hospitals but changed minimally for Army personnel treated in civilian hospitals. The Army's TBI hospitalization rates were generally higher than civilian rates in the early 1990s but by the late 1990s, most of the Army's rates were lower than or equal to the civilian rates.

The incidence of TBI-related hospitalization in the active duty US Army decreased markedly (75%) during the 1990s. As a result, most of the Army's TBI hospitalization rates were lower than civilian rates by the late 1990s. Effective injury prevention and changes in the Army population were two of the factors that likely contributed to the decrease in rates for all TBI severity levels, while changes in hospital admission practices likely contributed to the disproportionate decrease in the Army's rates for mild TBI.