RISK RATIOS OF INJURIES BASED ON MECHANISM IN 137,500 SERIOUSLY
INJURED TRAUMA CENTER
Mechanism is commonly used as a predictor of specific injuries. However, no
systematic study has been done. The weight attributable to mechanism is
by the likelihood ratio (LR), the ratio of its true positive rate (TPR),
with a diagnosis, and its false positive rate (FPR), its presence in the
the diagnosis (LR=TPR/FPR).
The relationships of injuries to mechanism was examined for the cohort of
137,500 seriously injured patients treated in Pennsylvania trauma centers
in the 8
years between the organization of their trauma system in 1986 and 1994.
of each three-digit ICD9 and E-code were calculated. For all E-code/ICD9
true and false positive rates and likelihood ratios were calculated. The 95%
confidence limits were calculated for all values.
The 137,500 patients had 559,307 coded injuries (ave.=4.1); 133 injuries
than once; 9 occurred in more than 10% of all patients, led by facial
29% and facial fractures in 20%. Injuries were caused by 103 mechanisms
once; the most common, collisions of motor vehicles, was almost twice as
as the second, falls on level ground (9%). Of 6605 E-code/ICD9 code
with very significant associations with injuries included facial
aircraft landings (LR increased the risk ratio 61 times, 95% CL=253-15
Accidental falls down holes most dramatically increased the risk of vertebral
fractures (LR = 17, 95% CL=21-15) whereas suicidal jumps mostly increased
the risk of
foot fractures (LR = 13, 95% CL=16-11). Falls down stairs reduced the
injuries to the thoracic blood vessels from the baseline value (LR =
CL=1/10-1/98). Listings with 95% CL have been generated for all ICD9
E-codes, and the likelihood ratios of all E-code/ICD9 combinations.
Trauma registries provide clinically useful information about the
mechanism and expected injuries when analyzed using risk ratios and
ratios. Such information is available for 6605 combinations of
For more information, please contact:
John R. Clarke, M.D.*,
Bonnie Lynn Webber, Ph.D.**,
Lawrence W. Bain, Jr.***; and
Waynes S. Copes, Ph.D.***
*Medical College of Pennsylvania and Hahnemann University;
**University of Pennsylvania; and
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