trauma scoring system and validation of...

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Trauma Scoring System and Trauma Scoring System and Validation of ICISSValidation of ICISS

(ICD based Injury Severity Score)(ICD based Injury Severity Score)

20042004년년 1010월월 2626일일서울의대서울의대 의료관리학교실의료관리학교실

김김 윤윤

OutlineOutline

Utility of trauma scoring system

Trauma scoring systemsPhysiologic measure

Anatomic measure

Combination of physiologic & anatomic score

ICISS validation studies

Potential future works

Utility of Trauma Scoring SystemUtility of Trauma Scoring System

Measurement and documentation of injury severity Pre-requisite for the development, evaluation, and improvement of trauma care system and injury control

TriageAugment clinical judgment of pre-hospital personnel with respect to on-scene treatment and transport

Evaluation of outcomeCompare the performance of a trauma care facility against a standard Assess the quality of care by a trauma care facility

• Preliminary outcome-based evaluation (PRE) chart: Identify patients with unexpected outcome

Comparison of effectiveness of treatment modalities

Epidemiologic data collection: Trauma registry

Risk Adjustment & Trauma ScoreRisk Adjustment & Trauma Score

환자요인Patient Factors

진료결과Patient

Outcome

치료효과Treatment

Effectiveness

무작위사건Random

Event+ + =

•진단명, 중증도•급성환자상태•연령, 성•육체적건강상태•동반질환•정신, 인지, 심리적기능상태

•문화적, 사회경제적특성•믿음, 행태

•생존/사망•환자상태•합병증, 의원성질환•자원사용량•만족도•건강관련삶의질•육체적기능상태

PRE ChartPRE Chart((Preliminary Outcome Based Evaluation)Preliminary Outcome Based Evaluation)

Trauma Scoring SystemsTrauma Scoring Systems

Physiologic scoreGCS (Glasgow Coma Scale)RTS (Revised Trauma Score)CRAMS (Circulation, Respiration, Abdominal/thoracic, Motor, Speech scale)APACHE (Acute Physiologic and Chronic Health Evaluation)

Anatomic scoreAIS (Abbreviated Injury Scale)ISS (Injury Severity Score)ICISS (ICD based Injury Severity Score)

Combination of physiologic & anatomic scoreTRISS (Trauma and Injury Severity Score)ASCOT (A Severity Characterization of Trauma) ICISS full model: ICISS+RTS

Glasgow Coma ScaleEye Opening Response

Spontaneous--open with blinking at baseline 4 To verbal stimuli, command, speech 3 To pain only (not applied to face) 2 No response 1

Verbal ResponseOriented 5 Confused conversation, but able to answer questions 4 Inappropriate words 3 Incomprehensible speech 2 No response 1

Motor ResponseObeys commands for movement 6 Purposeful movement to painful stimulus 5 Withdraws in response to pain 4 Flexion in response to pain (decorticate posturing) 3 Extension response in response to pain 2

(decerebrate posturing)No response 1

Glasgow Coma ScaleGlasgow Coma Scale

Score range: 3~15

Head Injury Classification:Severe Head Injury----GCS score of 8 or lessModerate Head Injury----GCS score of 9 to 12Mild Head Injury----GCS score of 13 to 15

(Adapted from: Advanced Trauma Life Support: Course for Physicians, American College of Surgeons, 1993)

AdvantagesCorrelated w/ mortalityWidely used for pre-hospital triage and determining level of consciousness Incorporated into the RTS

Revised Trauma Score (RTS)Revised Trauma Score (RTS)

RTS =0.9368(GCS) + 0.7326(SBP) + 0.2908(RR)

GCS: Glasgow Coma Scale

SBP: systolic blood pressure

RR: respiration rate

Revised Trauma Score (RTS)Revised Trauma Score (RTS)

10-29>296-91-50

>8976-8950-751-49

0

13 - 159 - 126 - 84 - 5

3

43210

RRSBPGCSCodedValue

* GCS: Glasgow Coma Scale, SBP: Systolic Blood Pressure, RR: Respiration Rate

RTS (Revised Trauma Score)RTS (Revised Trauma Score)

Score range: 0~7.84

Development Evolved from Triage Index and Trauma Score Subnormal value for any RTS variable: transport to trauma center

AdvantagesSimpleWidely used for prehospital triage More accurate prediction of outcome than Trauma Score

DisadvantageToo many missing data for GCS in Korea

예제예제> RTS > RTS 계산계산

어떤환자가 GCS가 13, 수축기 혈압이 70, 호흡수가 13회였다면, 이 환자의 RTS는 얼마인가?

RTS = 0.9368(GCS) + 0.7326x(수축기혈압) + 0.2908x(호흡수)

6.3756 =(0.9368 x 4) + (0.7326 x 2) + (0.2908 x 4)

CRAMS CRAMS (Circulation, Respiration, Abdominal/thoracic, Motor, Speech sca(Circulation, Respiration, Abdominal/thoracic, Motor, Speech scale)le)

Development Attempt to simplify the original trauma score for field triage

Score for each 5 category 0 (severe physiologic/neurologic deficit, abdominal/thoracic injury)2 (no deficit OR injury)

• Respiratory: Normal(2), Labored/Shallow(1), Absent(0)Major trauma: 8 or lessMinor trauma: 9 or above

APACHE APACHE (Acute Physiologic and Chronic Health Evaluation)(Acute Physiologic and Chronic Health Evaluation)

Development Classification system for ICUVariables used

• Values at ICU admission OR• Worst values during 1st 24 hours after ICU admission

Score range: 0~299Age Acute physiology: Temperature, Mean arterial pressure, Heart rate, Respiration rate, GCS, Oxygenation, Arterial pH, Serum sodium/ potassium/ creatinine, Hct, WBC, Chronic health : AIDS, Hepatic failure, Lymphoma, Metastatic cancer, Leukemia, Multiple myeloma, Immunosuppression, Chirrosis

APACHE APACHE (Acute Physiologic and Chronic Health Evaluation)(Acute Physiologic and Chronic Health Evaluation)

APACHE II12 variables Standardized coefficients for each patient group

• Treatment OutcomeAdmission eligibility Trauma patient group

• Post-operative/Non-operative• Multiple trauma/Head injury

APACHE IIIBetter predictionCommercial product

AIS (Abbreviated Injury Scale)AIS (Abbreviated Injury Scale)

Development Developed in 1969 for assessing severity of MVA• List of several hundreds of injuries

6 Body region • Head/Neck, Face, Thorax, Abdomen/Pelvic,

Extremities, External0(minor)~6(fatal)Revision: AIS-71 (original), AIS-85, AIS-90

Building block of ISS, standard injury severity score

AIS AIS (Abbreviated Injury Scale)(Abbreviated Injury Scale)A.I.S

SCORES

1 MINOR

2 MODERATE

3 SEVERE NOT LIFE

THREATENING

4 SEVERE

LIFE THREATENING

5 CRITICAL SURVIVAL

UNCERTAIN

HEAD

& NECK

Headache/dizziness 2ndary

to head trauma

Cervical spine strain with no

fracture or dislocation

Amnesia from accident

Lethargic/ stuporous

obtunded; can be aroused by verbal

stimuli Unconsciousne

ss 1 hr Simple vault

fracture Thyroid

contusion Branchial

plexus injury Dislocation or

fracture spinous or

Unconsciousness 1-6 hrs

Unconsciousness < 1 hr with

neurological deficitFracture base of

skull Comminuted compound or

Depressed vault fracture

Cerebral contusion/Subarachnoid hemorrhage

Intimal tear/thrombosis

carotid A.

Contusion larynx, pharynx

Unconsciousness 1-6 hrs

with neurological

deficit Unconsciousne

ss 6-24 hrs Appropriate

response onlyto painful

stimuli Fractured skull

with depression >

2cm, lac dura or tissue

loss Intracranial hematoma

100cc

Unconsciousness with

inappropriate movement

Unconscious > 24 hrs

Brain stem injury

Intracranial hematoma > 100 cc

Complete cervical cord lesion C4 or

below

AIS to ICD ConversionAIS to ICD Conversion

AIS ICD-9CM

Disadvantage 1:M mapping No appropriate AIS code for some ICD codes Not always correct assignmentCoding quality: creeping Limited # of ICD codes in a discharge summary

ISS (Injury Severity Score)ISS (Injury Severity Score)

ISS = AIS(1)2+AIS(2)2+AIS(3)2

Need a summary score based on AIS for multiple injuries

Value from 1 to 75

• Patients w/ AIS “6” injury assign ISS “75”

Sample ISS ScoreSample ISS Score

50 Injury Severity Score:

0 No Injury External

3 Fractured femur Extremity

25 25

Minor Contusion of LiverComplex Rupture Spleen

Abdomen

16 4 Flail Chest Chest

0 No Injury Face

9 3 Cerebral Contusion Head & Neck

SquareTop Three

AIS InjuryDescription

Region

ISS (Injury Severity Score):ISS (Injury Severity Score):Disadvantages Disadvantages

Discounting the importance of body regionMortality rates for subsets of ISS=16 cohort• Head/neck 17.2%• Face 0.0%• Thorax 6.1%• Abdomen 10.5%

Limits in considering severity of multiple injuries

Only consider 3 most severe injuries

MTOSMTOS(Major Trauma Outcome Study)(Major Trauma Outcome Study)

ObjectiveEstablish national normative outcome for traumaProvide trauma care institutions with objective data for evaluation of their quality assurance and outcome results

MethodsBegun 1982More than 170k seriously injured patients includedAbout 160 North American hospitals submitted data to the MTOSCombination of physiologic and anatomic measure for evaluation of injury severity = TRISS method

TRISS TRISS (Trauma & Injury Severity Score)(Trauma & Injury Severity Score)

TRISS

b=b0+b1(RTS)+b2(ISS)+b3(AGE)

Ps=1/(1+e-b)

MTOS regression coefficients

-1.9052-2.6676

-0.0768-0.1516

0.95441.1430

-1.2470-0.6029

BluntPenetrating

b3b2b1b0

TRISS TRISS (Trauma & Injury Severity Score)(Trauma & Injury Severity Score)

DisadvantageRequirement for independent data collection system

Inability to consider more than 3 injuries in deriving survival probability

예제예제: TRISS : TRISS

어떤 교통사고 환자가 RTS가 6, ISS가 18, 연령은 35세였으며, 관통상은 없었다면 TRISS에 의한 이 환자의 생존확률은 얼마인가?

1단계관통상이 없으므로 둔상의 TRISS 계수를 이용한다.

2단계b = b0 + b1 x (RTS) + b2 x (ISS) + b3 x (연령)

• = -1.2470 + (0.9544x6) + (-0.0768x18) + (-1.9052x0) • 3.097 = -1.2470 + 5.7264 -1.3824 + 0

3단계 : 생존확률(Ps) = 1/(1+e-b) e = 2.718 e-3.097 = 0.0452 생존확률(Ps) = 1/(1+e-b) = 1/(1+0.0452) = 0.9568

ICISSICISS(ICD based Injury Severity Score)(ICD based Injury Severity Score)

SRR (Survivor Risk Ratio)Number of patients that survived with ICDjSRRICDj =

Number of patients with ICDj

ICISS survival probabilityICISS = SRRICD(1) x SRRICD(2) ...... x SRRICD (10)

• Liver Laceration (0.9), EDH (0.8) ICISS=0.9*0.8=0.72ICISS full model

• b=b0+b1(RTS)+b2(ICISS)+b3(AGE)

AdvantageUse of multiple injuries in deriving survival probabilityMuch less effort required for data collection than ISS and TRISS

SRR Table: ExampleSRR Table: Example

0.988 2 169 171 Superficial injury of lip and oral cavityS005

1.000 -108 108 Superficial injury of earS004

1.000 -100 100 Superficial injury of noseS003

1.000 -167 167 Other superficial injuries of eyelid and periocular areaS002

0.993 3 422 425 Contusion of eyelid and periocularareaS001

0.968 52 1,588 1,640 Superficial injury of scalpS000

1.000 -11 11 Superficial injury of headS00

SRRDead Live Total patients ICD code descriptionICD

code

ICISSICISS(ICD based Injury Severity Score)(ICD based Injury Severity Score)

ICD 코드 이용

외상환자 등록체계(Trauma registry)와 같

은 별도의 자료수집체계 불필요

ISS의 단점 보완

다발성 외상의 중증도 평가

외상 유형별 중증도에 대한 경험적 평가

ISS, TRISS 보다 우수한 예측타당도

진료결과의진료결과의 평가평가

Risk-adjusted OutcomeRisk(severity) + Quality = Outcome

Z-scoreZ = (A-E)/SS = √ Pi*(1-Pi)+1.96 < or > -1.96

W-scoreW=(A-E) / (N/100)

Study(1): ObjectiveStudy(1): Objective

To evaluate the predictive validity of

ICD-10 based ICISS as a predictor of

mortality

for patients with blunt injuries

By comparing with ISS, TRISS, and ICD-

9CM based ICISS

Study(1): FrameworkStudy(1): Framework

TRISS Database of Two EMCs

(367 patients)

TRISS Database of Two EMCs

(367 patients)

Survey of ICD-9CM &

ICD-10 codes

Survey of ICD-9CM &

ICD-10 codes

ICD-10 SRR

ICD-10 SRR

North Carolina Trauma Database(89,827 patients)

North Carolina Trauma Database(89,827 patients)

Korean EMCTrauma Database(47,750 patients)

Korean EMCTrauma Database(47,750 patients)

ICD-9CM SRR

ICD-9CM SRR

Predictive Validityof ICD-9CM based

ICISS

Predictive Validityof ICD-9CM based

ICISS

Predictive Validityof ISS and TRISS

Predictive Validityof ISS and TRISS

Predictive Validity of ICD-10 based

ICISS

Predictive Validity of ICD-10 based

ICISS

Study(1): Study(1): Measure of PerformanceMeasure of Performance

Measures of DiscriminationDisparity, Sensitivity(%), Specificity(%)

Misclassification rate(%)

Area under the ROC (receiver operating characteristic curve)

Goodness-of-fit statistics Hosmer-Lemeshow statistic

ICISS vs. ISS: ICISS vs. ISS: All Blunt InjuryAll Blunt Injury

ISSICD-9CM

basedICISS

ICD-10basedICISS

Disparity 0.245 0.378 0.194

Sensitivity(%) 43.6 56.4 38.5

Specificity(%) 97.2 97.9 94.1Misclassification rate(%) 14.2 10.9 17.7

ROC analysis1) 0.892 0.909 0.843

H-L Statistic2) 9.381(p=0.226)

12.891(p=0.116)

5.147(p=0.742)

1) ROC analysis : Receiver Operating Characteristic analysis2) H-L Statistic: Hosmer- Lemeshow Statistic

ICISS Full Model vs. TRISS: ICISS Full Model vs. TRISS: All Blunt InjuryAll Blunt Injury

TRISSICD-9CM

based ICISSFull Model

ICD-10based ICISSFull Model

Disparity 0.644 0.737 0.627

Sensitivity(%) 75.6 82.1 73.1


ROC analysis1) 0.958 0.976 0.956


7.738(p=0.460)

7.294(p=0.505)


ICISS Full Model vs. TRISS: ICISS Full Model vs. TRISS: Intracranial InjuryIntracranial Injury

TRISSICD-9CM



Disparity 0.684 0.769 0.629

Sensitivity(%) 79.7 84.7 76.3


ROC analysis1) 0.829 0.882 0.791


9.053(p=0.338)

3.417(p=0.906)


ICISS Full Model vs. ISS: ICISS Full Model vs. ISS: NonNon--intracranial Injuryintracranial Injury

TRISSICD-9CM



Disparity 0.511 0.626 0.596

Sensitivity(%) 57.9 57.9 63.2


ROC analysis1) 0.938 0.979 0.97


0.968(p=0.998)

3.618(p=0.890)


Study(2): ObjectivesStudy(2): Objectives

To evaluate the utility of ICISS To detect preventable deathsTo compare the performance of trauma care facilities

Through comparing the agreement between judgments derived from ICISS survival probability and those derived from a professional panel method

Study(2): FrameworkStudy(2): Framework

6 EMCs• 2 Tertiary / 4 Non-tertiary

6 EMCs• 2 Tertiary / 4 Non-tertiary

Trauma Deaths (131)

Trauma Deaths (131)

ICISS Survival Probability

Professional Panel Review on

Preventability

Professional Panel Review on

Preventability

W-scores of Each EMC using ICISS

W-scores of Each EMC using ICISS

ICISS Survival Probability

Agreement Rates

Agreement Rates

CorrelationCoefficient

CorrelationCoefficient

Trauma Inpatients

(1,087)

Trauma Inpatients

(1,087)

Study(2): Data CollectionStudy(2): Data Collection

Two professional panels Each panel: emergency physician(1), general surgeon(1), neurosurgeon(1)

Review process Independent review by each panel member using structured review form Decision rule: Unanimous agreement rule Time for review per case: about 1 hourPreventability:

• Preventable (P): Ps ≥ 0.75• Potentially preventable (PP): Ps 0.25~0.75• Non-preventable (NP): Ps < 0.25

Data collection for ICISS RTS : GCS, SBP, RRMaximum of 10 ICD-10 codes

Study(2): AnalysisStudy(2): Analysis

Agreement of judgment on preventable deaths Overall agreement ratesKappa statistics

Correlation between the preventable death rate and the W-score in each EMC

W-statistic = (A-E)/(n/100)• Represents excess survival or excess mortality per 100

patients after adjusting severity of trauma patients

• A: Actual Survivors• E: Expected Survivors• N : Number of Observations

Spearman correlation coefficient

Agreement between the Preventability of the Panel and ICISS Survival Probability

TotalNPP/PPPrevent

-ability

ICISS SubtotalPPP

131(100.0)

[ 100.0]78

( 59.5)53

( 40.5)36

( 27.5)17

( 13.0)Total

48 (100.0) [ 36.6]

41 ( 85.4)[ 31.3]

7 ( 14.6)[ 5.3]

7 ( 14.6)[ 5.3]

0 ( 0.0)[ 0.0]0.25<

43 (100.0) [ 32.8]

27 ( 62.8)[ 20.6]

16 ( 37.2)[ 12.2]

13 ( 30.2)[ 9.9]

3 ( 7.0)[ 2.3]

0.25-0.75

40 (100.0) [ 30.5]

10 ( 25.0)[ 7.6]

30 ( 75.0)[ 22.9]

16 ( 40.0)[ 12.2]

14 ( 35.0)[ 10.7]

≥ 0.75

* P: Preventable, PP; Potentially preventable, NP; Nonpreventable

Agreement between the Preventability of the Panel and ICISS Survival Probability

2-way classification: P/PP, NPOverall agreement: 66.4%Kappa : 0.36• McDermott(1996) : 65.6% (0.35)

3-way classification: P, PP, NPOverall agreement: 51.9%Kappa : 0.26

ICISS ICISS 사망확률과사망확률과 예방가능한예방가능한 사망사망-- 병원병원 내내 질향상질향상 활동활동 도구도구 --

양성예측도 : 55.4% (46/83)

Cayten (1991) : 21.5%

Karmy-Jones (1992) :16.1%

음성예측도 : 85.4% (41/48)

Correlation between WCorrelation between W--score and Preventable score and Preventable Death Rate by Emergency Medical CenterDeath Rate by Emergency Medical Center

(1.54, 37.0)

(-0.11, 50.0)(0.56, 55.0)

(2.66, 34.6)

(4.44, 21.1)

(-8.98, 47.8)

0.0

20.0

40.0

60.0

-9.00 -6.00 -3.00 0.00 3.00 6.00 9.00W-score

Prev

enta

bilit

y(%

)

*Numbers in parentheses refer to W-score and preventable death rate of each emergency medical center.

Spearman=0.77(p=0.07)

ConclusionConclusion

The ICISS methodology can be extended to ICD-10 horizon as a standard injury severity measure in the place of TRISS for blunt injury.

The ICISS is useful in detecting preventable deaths and in comparing the performance of trauma care facilities

Potential Future WorkPotential Future Work

Development of standardized coefficients of a ICISS prediction model based on a large scale study

Possible to evaluate quality of care of emergency medical centers based on national standards

Similar to MTOS (major trauma outcome study) of North America

Development of ICISS prediction models considering various mechanisms of injury which could affect validity of trauma scoring system

Blunt injury: Motor vehicle accident, low fall, other blunt injury

Penetrating injury: gunshot wound, stab wound

Questions?Questions?

trauma scoring system and validation of...

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