The impact of the AIS 2005 revision on injury severity scores and clinical outcome measures.
BACKGROUND
The abbreviated injury scale (AIS) was updated in 2005 from the AIS 1998 version. The purpose of this study is to describe the effects of this change on injury severity scoring and outcome measures.


METHODS
Analyses were performed on all trauma patients consecutively admitted over a 6-month period at two geographically separate Level I trauma centers. Injuries were manually double-coded according to the AIS 05 and the AIS 98. Changes in AIS, ISS, and new ISS (NISS) were analysed using paired t-tests. Apparent differences in outcome by ISS strata (<16, 16-24, >24) were compared for AIS 05 versus AIS 98 using the Wald-type statistic. Lastly, the percent of patients with a change in ISS strata are reported.


RESULTS
There were 2250 patients included in the study. Nearly half (46.4%) of AIS codes changed, resulting in a different AIS score for 18.9% of all codes. The mean ISS was significantly lower using the AIS 05 (11.7) versus the AIS 98 (13.3, p<0.001). Similarly, the mean NISS was significantly lower (16.3 versus 18.7, p<0.001). In the ISS strata 16-24 an apparent increase in mortality, length of stay, and percent of patients not discharged home was observed for the AIS 05 versus AIS 98. Changes in outcome measures for this stratum were as follows (AIS 98 versus AIS 05): mortality, 4.3% versus 7.7% (p=0.002); hospital length of stay, 5.2 days versus 7.3 days (p<0.001); percent of patients not discharged home, 39.2% versus 49.3% (p<0.001). Finally, there was a 20.5% reduction in patients with an ISS>or=16 and a 26.2% reduction in patients with an ISS>or=25 using the AIS 05.


CONCLUSIONS
The AIS revision had a significant impact on overall injury severity measures, clinical outcome measures, and percent of patients in each ISS strata. Therefore, the AIS revision affects the ability to directly compare data generated using AIS 05 and AIS 98 which has implications in trauma research, reimbursement and ACS accreditation.
Salottolo
Kristin
K
Trauma Research Department, Swedish Medical Center, Englewood, CO 80113, USA.
Settell
April
A
Uribe
Phyllis
P
Akin
Shelley
S
Slone
Denetta Sue
DS
O'Neal
Erika
E
Mains
Charles
C
Bar-Or
David
D
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D014193:Trauma Centers / Q000706:statistics & numerical data; D014947:Wounds and Injuries / Q000145:classification / Q000401:mortality*