1. Probability of Survival (Ps) & Hospital Survival Rate (Ws) The Trauma Audit & Research Network (TARN)

2. Probability of Survival
Once ISS is assigned
Probability of Survival (Ps) calculated each submission

3. Why calculate PS? Need to assign weight to deaths and survivors.
Some deaths more statistically significant than others.
Case mix adjustment.
Performances measurement: hospital and networks.

4. Charlson comorbidity index adds ‘weighting’ PMC
Ps history
TARN developed first Ps model in 2004
Remodelled in 2007, 2009, 2012, 2014 and 2017
Components used in Ps since 2014 (best predictors of outcome):
ISS
Age
Gender
GCS
Pre-Existing Medical Conditions (PMC)
Charlson comorbidity index adds ‘weighting’ PMC

5. i $ Ps17 (launched July 17) Age Gender ISS GCS/ intubation PMC
Ps17 calculation $
Patient PS: 63% *
*Charlson index (1984, revised).

6. What is Ps?
PS% is retrospective measure of pts with same profile on TARN database.
TARN database: past 4 years (Approx 200,000 cases)
Ps = 63%, then 63 out of every 100 patients with that profile have previously survived.
37 out of every 100 patients have previously died.

7. Probability of Survival
Ps is calculated using:
GCS taken on arrival in ED at first receiving hospital
where unavailable
Pre Hospital GCS
Presence of Intubation/ventilation
Impute a “probable” GCS (equivalent weighting)

8. Pre-Existing Medical Conditions
Ps17 Weighting groups
Pre-Existing Medical Conditions
Weight
PMC group
Bone conditions
Connective tissue disorder
GU/GI disease
Neurological disorders
No PMC
Other
Paraplegia
Pulmonary disease
1-5
Alcohol abuse
Blood conditions
Cancer
CVA
Dementia
Diabetes
Heart failure
HIV
Mental health MI
Renal disease
Vascular disease
6-10
Haematological malignancy
Liver disease
Metastatic cancer

9. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 25
Gender: Male
ISS: 25
GCS: 15
PMC:
Nil i
Ps17 calculation $
Ps: 99.2%

10. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 25
Gender: Male
ISS: 25
GCS: 15
PMC:
Alcohol abuse i
Ps17 calculation $
Ps: 98.6%

11. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 25
Gender: Male
ISS: 25
GCS: 15
PMC:
Alcohol Abuse
Liver Disease i
Ps17 calculation $
Ps: 95.7%

12. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 25
Gender: Male
ISS: 25
GCS: 3
PMC:
Alcohol Abuse
Liver Disease i
Ps17 calculation $
Ps: 21.6%

13. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 65
Gender: Male
ISS: 25
GCS: 3
PMC:
Alcohol Abuse
Liver Disease i
Ps17 calculation $
Ps: 4.7%

14. Weightings for Age, GCS, Gender & PMC
Ps17
Weightings for Age, GCS, Gender & PMC
Age: 65
Gender: Female
ISS: 25
GCS: 3
PMC:
Alcohol Abuse
Liver Disease i
Ps17 calculation $
Ps: 5.09%

15. Importance of accurate injury detail
Ps17
Importance of accurate injury detail
Full injury detail
Code
Spiral Shaft of Femur
Open complete articular fracture to distal Radius
Open book fracture to pelvis with blood loss >20%
3 ribs fractured on left
Extensive bilateral cerebral contusion
Skull vault fracture
Grade III (OIS grade) Spleen laceration
Accurate ISS
Accurate Ps 59
58%
Incomplete injury detail
Code
Spiral Shaft of Femur
Fracture to distal Radius
Fracture to pelvis
Multiple ribs fractured on left
Cerebral contusion
Skull vault fracture
Spleen laceration
Incomplete ISS 22

16. Importance of accurate injury detail
Ps17
Importance of accurate injury detail
Age: 40
Gender: Male
ISS: 22
GCS: 5
PMC:
Nil i
Ps17 calculation $
Ps: 86%

17. PS breakdown: shown in Clinical reports & website
Ps Bandings
No. of patients in each band
Observed/Actual survivors
Expected survivors (compared to TARN database)
Difference = Observed – Expected x 100
No. in group
Ws = Difference x fracture of patients on database in each band
Hospital Survival Rate
95% Confidence Interval

18. Individual Hospital Survival Rate shown on website: English & Welsh sites only
+1.2 Survivors
Statistically significant outcome
(+0.39 to +1.97)
+1.2 Survivors
Not Statistically significant
(-1.83 to +4.2)

19. Comparative Survival rate (Ws) shown in Clinical reports for all sites
All hospitals
Your hospital
95% confidence intervals
July 17 onwards: MTC compared to MTC
TU compared to TU

20. You may wish to review negative bands – particularly deaths
PS breakdown
You may wish to review negative bands – particularly deaths

21. Example patients to review: Ps:45-65%
Age
Sex
ISS
GCS
Int
Outcome
PMC
Mechanism
Injuries
Submission ID
46.2% 46
Male 16 3
Yes
Death
N/K
Fall >2m
Skull Vault #
SDH NFS (AIS4)
Brain swelling
With large SDH & Liver disease: ISS= 25, Ps= 28% Ps
Age
Sex
ISS
GCS
Int
Outcome
PMC
Mechanism
Injuries
Submission ID
57.7% 94
Female 38 14 No
Death
N/K
Fall <2m
T cord transection (AIS5)
BOS # (AIS3)
Pelvic # (AIS2)
With GCS 3 & Dementia: Ps= 3%

22. Questions