Long-term air medical services system performance using APACHE-II and mortality benchmarking.
OBJECTIVE
Air medical transport programs have been in existence for two decades. During this time, no outcome measures have been developed for these services. The authors examined severity scoring and mortality data from their air medical service to characterize its performance and to identify trends in acuity and mortality over a 15-year period.


METHODS
APACHE-II scores derived at the time of transport and hospital mortality data have been concurrently recorded in the flight database for adult transports since 1986. The authors analyzed these data and examined the correlation between APACHE-II score at the time of transport and hospital mortality for the 15-year period 1986-2001.


RESULTS
13,808 adult transports were identified. APACHE data were available for 8,204 patients (59%) and mortality for 10,845 (79%), respectively. The number of transports increased from 935 to 1,231 per year. Mean APACHE-II for all patients was 11.6 +/- 8.4. Overall mortality was 22%. Both patient acuity and mortality were trending upward over time. The correlation between APACHE-II and mortality was close and linear (mortality = 0.018 x APACHE-II -0.0243, R2 = 0.97).


CONCLUSIONS
Both severity of illness and mortality of air-transported patients appear to be increasing slowly over time in response to changes in the health care system. The strong correlation between APACHE-II performed at the time of transport and mortality validates this technique for benchmarking. The slope of this correlation is an outcome-based characteristic of system performance that may allow monitoring of a system over time and comparisons between systems.
Silbergleit
Robert
R
University of Michigan Department of Emergency Medicine, UMMC TC, Ann Arbor 48109-0303, USA. robie@umich.edu
Burney
Richard E
RE
Nelson
Kris
K
Snyder
Michael
M
Lowell
Mark J
MJ
Maio
Ronald F
RF
D018806:APACHE; D000328:Adult; D017732:Air Ambulances / Q000592:standards* / Q000706:statistics & numerical data; D019985:Benchmarking; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D008824:Michigan / Q000453:epidemiology; D017063:Outcome Assessment, Health Care / Q000379:methods*; D012720:Severity of Illness Index; D016019:Survival Analysis