Measuring Trauma Outcomes Injury Severity Score ISS Probability

Measuring Trauma Outcomes Injury Severity Score (ISS) Probability of Survival (Ps 17) Hospital Survival rate (Ws) BOAST 4 Chest Wall Injury report The Trauma Audit & Research Network (TARN)

Injury Coding Ø Injury coding performed centrally at TARN Ø Ensuring coding uniformity Ø Coders check injury descriptions & imaging reports Ø Abbreviated Injury Scale dictionary (AIS 2005) currently used Ø Every submission assigned an Injury Severity Score (ISS) Ø 75, 000 submissions per year coded

Abbreviated Injury Scale: AIS Ø THE Internationally recognised system for injury scoring Ø Produced by AAAM (Association for the Advancement of Automotive Medicine) in U. S. A Ø Introduced in 1970, originally for Vehicle Crash investigators Ø AIS 2005 version >2000 injury descriptors Ø Anatomically based system, ranking injuries according to severity on a 6 point ordinal scale

AIS: 6 point severity scale AIS (Severity) Grade Injury example 1 Minor Bruise to abdomen 2 Moderate Small Liver laceration 3 Serious Liver laceration with >1 litre of blood loss 4 Severe Ruptured liver 5 Critical Liver laceration involving hepatic vessels 6 Maximum Avulsed liver

AIS Severity indicates The relative risk of “threat to life” in an average person who sustains the coded injury as his or her only injury It’s not a disability scale

AIS code structure: 7 digits Code Injury Numerical identifier Severity Score 853271. 3 Comminuted Femoral Shaft # 853271 . 3 140656. 5 Large Subdural haemorrhage 140656 . 5

Abbreviated Injury Scale: Sections Skin Degloving Penetrating Crush Traumatic Amputation Nerve Hypothermia Asphyxia: Hanging/Strangulation Drowning Frostbite Vessel Joint Skeletal Burns Inhalation Electrocution

AIS: Spinal Injuries Ø Cervical Spine (C 1 -C 7) Ø Thoracic Spine (T 1 -T 12) Ø Lumbar spine (L 1 -L 5) Severity can be affected by location of spinal injury

AIS: Confirmed injuries only Suspected injuries Possible injuries Probable injuries Ruled out injuries

AIS: Not Coded Ø Infections Ø Pneumonia Ø Death Ø Blindness Ø Miscarriage Ø Epilepsy following head injury Ø Pulmonary embolism following skeletal injury Don’t affect Severity score

NFS: Not Further Specified This appears throughout the AIS dictionary & allows the coding of injuries when detailed information is lacking Example: Injury description = Liver laceration Coded as: 541820. 2 (Liver laceration NFS)

AIS 6: Maximum score AIS 6 not used just because a patient dies! Has to be documented medical evidence of an AIS 6 injury

AIS 6: Maximum score Head or Neck ØBrain stem: laceration, crush, penetrating or transection ØC 3 or higher complete cord transection or contusion ØSigmoid or Transverse sinus or Internal carotid artery: Bilateral lacerations Thorax Ø Heart: rupture, multiple lacerations or avulsion Ø Total chest crush Ø Aortic rupture + haemorrhage not confined to mediastinum Ø Bilateral pulmonary artery or vein transection Ø Severe inhalation Abdominal & Pelvic contents Ø Liver avulsion External Ø 2 nd or 3 rd degree burns > 90% Total Body Surface Ø Massive Whole body Explosion type injury

AIS: Localisers 2 additional localiser codes, allow coding of: ØLocaliser 1 Side or aspect of an injury e. g. Right, left, Upper, Temporal, Frontal ØLocaliser 2 Actual Site of an injury e. g. 5 th rib, 12 th Thoracic vertebrae, 2 nd toe Numerical identifier • Don’t affect ISS • Used mainly in Research Severity Localiser 1 Localiser 2

AIS dictionary Available only from: www. aaam. org • • • Latest Version: AIS 2015 recently released $225 each + shipping TARN will moving to AIS 2015 at end of year All existing codes will be mapped over All Trusts notified well in advance

Injury Coding exercise

EXAMPLE SUBMISSION 1: INJURIES Page AIS code Spiral Shaft of Femur 147 853251. 3 Open complete articular fracture to distal Radius 127 752372. 3 Open book fracture to pelvis with blood loss >20% 159 856164. 5 3 ribs fractured on left 82 450203. 3 Extensive bilateral cerebral contusion 44 140626. 5 Skull vault fracture 49 150400. 2 Grade III (OIS grade) Spleen laceration 96 544224. 3

Calculating the ISS Injury Severity Score

Calculating the ISS: Step 1 Determine the scores of the individual injuries using the Abbreviated Injury Scale

Calculating the ISS: Step 2 Identify the highest severity score in each body area

Injury Severity Score: 6 body areas ØHead & Neck & Cervical spine ØFace ØChest & Thoracic spine ØAbdomen & pelvic contents & Lumbar spine ØExtremities & bony pelvis ØExternal (incl. Skin injuries and Burns)

Head Extensive bilateral cerebral contusion 140626. 5 Skull vault fracture 150400. 2 Thorax 3 ribs fractured on left 450203. 3 Abdomen Grade III Spleen laceration 544224. 3 Extremities Open complete articular fracture to distal Radius 752372. 3 Open book fracture to pelvis with blood loss >20% 856164. 5 Spiral Shaft of Femur 853251. 3

Calculating the ISS: Step 3 Square the highest score in each body area

Head Extensive bilateral cerebral contusion 5² =25 140626. 5 Skull vault fracture 150400. 2 Thorax 3 ribs fractured on left 3² =9 450203. 3 Abdomen Grade III Spleen laceration 3² =9 544224. 3 Extremities Open complete articular fracture to distal Radius 752372. 3 Open book fracture to pelvis with blood loss >20% 5² = 25 856164. 5 Spiral Shaft of Femur 853251. 3

Calculating the ISS: Step 4 ØCode individual injuries ØIdentify the highest score in each body area ØSquare the highest score in each body area ØAdd together the highest AIS 2 from 3 different body areas

Head Extensive bilateral cerebral contusion 5² =25 140626. 5 Skull vault fracture 150400. 2 Thorax 3 ribs fractured on left 3² =9 450203. 3 Abdomen Grade III Spleen laceration 3² =9 544224. 3 Extremities Open complete articular fracture to distal Radius 752372. 3 Open book fracture to pelvis with blood loss >20% 5² = 25 856164. 5 Spiral Shaft of Femur 853251. 3

Injury Severity Score (ISS) = 59

Injury Severity Score (ISS) Body area Injury AIS code Head Closed vault fracture 150402. 2 2² = 4 Thorax 5+6 ribs fractured on left 450202. 2 2² = 4 ISS = 8

Injury Severity Score (ISS) Body area Injury AIS code Head Closed vault fracture 150402. 2 2² = 4 Thorax 5+6 ribs fractured on left 450202. 2 2² = 4 External Lower limb – skin laceration 810600. 1 1² = 1 ISS = 9

Injury Severity Score (ISS) ØRanges from 1 to 75 ØMaximum 75 achieved in 2 ways: 1. Severity 5 in 3 different body areas 52 + 52 = 75 2. ISS convention: AIS = 6 in any body area, ISS = 75

Importance of Injury Detail ØLength, depth or Grade of lacerations (especially to internal organs) ØDepth, size and location of haemorrhages and contusions (especially in the brain) ØOpen or Closed fractures ØStability & site of Fractures (e. g. Comminuted/Displaced Shaft/Proximal/Distal fracture) ØArticular (joint) involvement (e. g. Intra-articular, extra-articular) ØBlood loss ØVessel damage ØLocation & number of rib fractures ØCompression or effacement of ventricles/brain stem cisterns ØNeurology associated with spinal cord injuries ØGrade, Instability, Blood loss or Vascular damage associated with Pelvic Fractures ØCardiac arrest associated with asphyxia or drowning ØEnsure all injuries are documented ØInclude imaging reports or Post Mortems for every submission. Jan 17: Grade now requested for pelvic ring fixations

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

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.

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

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

What is Ps? PS% is retrospective measure of pts with same profile on TARN database: past 4 years (Approx 300, 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.

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

Ps 17 Weighting groups Pre-Existing Medical Conditions Weight PMC group 0 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

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 25 Gender: Male ISS: 25 GCS: 15 PMC: i i i Ps 17 calculation $ Ps: 99. 2% Nil

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 25 Gender: Male ISS: 25 GCS: 15 i i Ps 17 calculation $ Ps: 98. 6% PMC: Alcohol abuse i

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 25 Gender: Male ISS: 25 GCS: 15 i i Ps 17 calculation $ Ps: 95. 7% PMC: Alcohol Abuse Liver Disease i

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 25 Gender: Male ISS: 25 GCS: 3 i i Ps 17 calculation $ Ps: 21. 6% PMC: Alcohol Abuse Liver Disease i

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 65 Gender: Male ISS: 25 GCS: 3 i i Ps 17 calculation $ Ps: 4. 7% PMC: Alcohol Abuse Liver Disease i

Ps 17 Weightings for Age, GCS, Gender & PMC Age: 65 Gender: Female ISS: 25 GCS: 3 i i Ps 17 calculation $ Ps: 5. 09% PMC: Alcohol Abuse Liver Disease i

Ps 17 Importance of accurate injury detail Full injury detail Code Spiral Shaft of Femur 853251. 3 Open complete articular fracture to distal Radius 752372. 3 Open book fracture to pelvis with blood loss >20% 856164. 5 3 ribs fractured on left 450203. 3 Extensive bilateral cerebral contusion 140626. 5 Skull vault fracture 150400. 2 Grade III (OIS grade) Spleen laceration 544224. 3 Incomplete injury detail Code Spiral Shaft of Femur 853251. 3 Fracture to distal Radius 752371. 2 Fracture to pelvis 856151. 2 Multiple ribs fractured on left 450210. 2 Cerebral contusion 140604. 3 Skull vault fracture 150400. 2 Spleen laceration 544220. 2 Accurate ISS 59 Incomplete ISS 22 Accurate Ps 58%

Ps 17 Importance of accurate injury detail Age: 40 Gender: Male ISS: 22 GCS: 5 PMC: i i i Ps 17 calculation $ Ps: 86% Nil

PS breakdown: shown on website & clinical reports (more later) • • • Ps Bandings No. of patients in each band Hospital Survival Rate= 0. 67 Observed/Actual survivors additional survivors per 100 Expected survivors (compared to TARN database) patients Difference = Observed – Expected x 100 No. in group 95% Confidence interval Ws = Difference x fraction of patients on database in each band Ws lies between this line

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)

Comparative Survival rate (Ws) shown in Clinical report: All hospitals Your hospital 95% confidence intervals

Funnel plots: Potential outlier (positive) Normal range All hospitals Lower Precision: Fewer cases Greater Precision: More cases (not as reliable) Hospitals shown by Precision (no. of cases) Ws must always be viewed in conjunction with Case ascertainment (more reliable)

Highlighting patients for Ws review Produce a Performance Review Indicators report (PRI) & review data in negative Ps bands: Particularly the deaths using the Data Quality Report

Example patients to review: Ps: 45 -65% Ps Age Sex ISS GCS Int Outcome PMC Mechanism Injuries Submission ID 46. 2% 46 Male 16 3 Yes Death N/K Fall >2 m Skull Vault # SDH NFS (AIS 4) Brain swelling 999900004552 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 <2 m T cord transection (AIS 5) BOS # (AIS 3) Pelvic # (AIS 2) 999900004517 With GCS 3 & Dementia: Ps= 3%

The Performance Review Indicators report

Performance Review Indicators Includes Approved cases only Highlights Key Performance Measures that underpin TARN reports Submission ID NHS number Age Gender Injury Mechanism ISS & ISS band GCS Intubation Probability of Survival Outcome at 30 days Incident date/time Arrival date/time Discharge date LOS ICU LOS Transfer from/to Mode of arrival PROMS Available Trauma Team Senior Dr in ED Date/Time First Dr in ED Date/Time No of Operations Date/time 1 st Operation Time to 1 st Operation Date/Time 1 st CT Time to 1 st CT Incident & Home postcodes Triage Tool Pre Alert PRF Wards visited (first 2) Visited ED NICE criteria Shocked Patient (SBP<110) Rehab Prescription GOS Case for Review Most severely injured body region Maximum AIS All Injuries

Analysing your own data using PRI Report q Create a PRI report q List specific patients e. g. q Ps bands: To review q AIS 3+ Head injuries CT within 1 hour q ISS 16+ who saw a Consultant q Produce a breakdown

BOAST 4 Guidelines derived from BOA & BAPRAS Severe Open fractures of Tibia: Gustilo Anderson grade 3 b or 3 c Guideline requires: § § Early identification of severe open fractures of the tibia Joint care from orthopaedic & plastic surgeons Surgical wound debridement & operative fracture stabilisation within 24 hours Definitive soft-tissue cover within 72 hours of injury BOAST 4 report shows compliance with standard

Chest Wall Injuries q Patients with chest wall injuries (fracture of rib/s and/or sternum) q Proportion of: Ø >3 ribs fractured Ø chest wall fixations Ø Attendances by pain team q Lists all injuries coded

Questions