Using Trauma Injury Severity Score (TRISS) variables to predict length of hospital stay following trauma in New Zealand.
OBJECTIVE
To develop and assess the predictive capabilities of a statistical model that relates routinely collected Trauma Injury Severity Score (TRISS) variables to length of hospital stay (LOS) in survivors of traumatic injury.


METHODS
Retrospective cohort study of adults who sustained a serious traumatic injury, and who survived until discharge from Auckland City, Middlemore, Waikato, or North Shore Hospitals between 2002 and 2006. Cubic-root transformed LOS was analysed using two-level mixed-effects regression models.


RESULTS
1498 eligible patients were identified, 1446 (97%) injured from a blunt mechanism and 52 (3%) from a penetrating mechanism. For blunt mechanism trauma, 1096 (76%) were male, average age was 37 years (range: 15-94 years), and LOS and TRISS score information was available for 1362 patients. Spearman's correlation and the median absolute prediction error between LOS and the original TRISS model was p=0.31 and 10.8 days, respectively, and between LOS and the final multivariable two-level mixed-effects regression model was p=0.38 and 6.0 days, respectively. Insufficient data were available for the analysis of penetrating mechanism models.


CONCLUSIONS
Neither the original TRISS model nor the refined model has sufficient ability to accurately or reliably predict LOS. Additional predictor variables for LOS and other indicators for morbidity need to be considered.
Schluter
Philip J
PJ
School of Public Health and Psychosocial Studies, AUT University, Auckland, New Zealand. philip.schluter@aut.ac.nz
Cameron
Cate M
CM
Davey
Tamzyn M
TM
Civil
Ian
I
Orchard
Jodie
J
Dansey
Rangi
R
Hamill
James
J
Naylor
Helen
H
James
Carolyn
C
Dorrian
Jenny
J
Christey
Grant
G
Pollard
Cliff
C
McClure
Rod J
RJ
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009017:Morbidity / Q000639:trends; D009520:New Zealand / Q000453:epidemiology; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D015599:Trauma Severity Indices; D014947:Wounds and Injuries / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology; D055815:Young Adult