Defining Severity, Time-Sensitivity and Predictability of Common - - PowerPoint PPT Presentation

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Defining Severity, Time-Sensitivity and Predictability of Common Pediatric Injuries

Joel Stitzel, PhD – PI Andrea Doud MD, Ashley Weaver PhD, Jennifer Talton MS, Ryan Barnard MS, Samantha Schoell BS, Wayne Meredith MD, Shayn Martin MD, John Petty MD

Wake Forest University School of Medicine, Virginia Tech – Wake Forest University Center for Injury Biomechanics

Wake Forest Baptist Medical Center

Disclosures

• Funded by the Center for Child Injury

Prevention Studies (CChIPS)

• Multi-university Industry/University

Cooperative Research Center (I/UCRC)

• Supported by Childress Institute for Pediatric

Trauma

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Injury Severity Measures

 Currently, the most widely used severity metrics are based upon the Abbreviated Injury Scale (AIS)

X X X X X X . X

Severity metric

AIS Description 1 Minor 2 Moderate 3 Serious 4 Severe 5 Critical 6 Maximum

Anatomic classification

AIS Severity metrics:

• Not created for use in children
• Based on consensus opinion
• May not capture all aspects of injury that determine

need for treatment at a Trauma Center (TC)

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Injury Severity Scoring Alternative

Target injuries: Injuries likely to need treatment at a TC given their severity, time sensitivity and predictability

Time- Sensitivity Predictability

Severity

 Project Goal: Determine the severity, time-sensitivity & predictability of most common pediatric injuries within 4 age subsets

0-4 yr 5-9 yr 10-14 yr 15-18 yr

Severity

 NTDB 2002-2012 utilized to determine mortality risk ratios (MRRs) for the most common pediatric injuries  Largest aggregation of trauma registry data

# Dying after injury Total # with injury = MRR

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Fewer Patients Dying with Injury (Less Severe) More Patients Dying with Injury (More Severe)

Severity

 The most common pediatric injuries result in differing mortality risks between age groups.

0.07 0.04 0.03 0.05 0.02 0.04 0.06 0.08 0.1

0-4yo 5-9yo 10-14yo 15-18yo

Median MRR Median MRR by Age Group

p=0.04 p=0.03 p<0.0001 p<0.001

n=112 injuries n=125 injuries n=156 injuries n=194 injuries

Time Sensitivity

Survey of Expert Opinion Experts included pediatric & orthopaedic surgeons and emergency medicine physicians For each injury, experts asked:

• 1. Does this injury require treatment at a TC?
• 2. How urgently does the injury require treatment

from a scale of 1 (not urgently) to 5 (urgently)?

Time Sensitivity

Injury Description: Kidney Laceration, Grade 2

Screen shot of Electronic Survey

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Time Sensitivity Scores

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0-4 year 5-9 year 10-14 year 15-18 year

Median TS Scores

Median Time Sensitivity Scores by Age Group

p<0.0001 p=0.0001 p=0.05 p=0.018

 Injuries in the youngest children are more time sensitive than injuries in the oldest children. Median Time Sensitivity Scores By Age Group

n=112 injuries n=125 injuries n=156 injuries n=194 injuries

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Predictability

Predictability Score

Consensus-derived “Occult Score” (survey) Data-Derived “Transfer Score” (NIS)

Consensus-Derived Occult Score

Experts surveyed For each question, participants asked to assess the likelihood that the injury might be missed on initial assessment

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Fewer Patients Requiring Transfer = Less Occult More Patients Requiring Transfer = More Occult

Data-Derived Transfer Score

National Inpatient Sample (NIS)

• Supported by HCUP
• Tracks national trends in health care use

Transfer Score

=

# with Injury transferred to TC Total # with Injury

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Predictability Scores

Median Predictability Score

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0-4 years 5-9 years 10-14 years 15-18 years

p=0.001 p<0.0001 p=0.04 p<0.0001 p=0.03

n=125 injuries n=156 injuries n=194 injuries

 Injuries in the youngest children less predictable (more occult & more highly transferred) than injuries in older children.

Median Predictability Scores By Age Group

n=112 injuries

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“AIS Glasses”

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Cerebrum Subarachnoid Hemorrhage (AIS 3) Open Tibia Fracture (AIS 3)

AIS Performance 0-4 year olds

Severity* 0.69 (High) 0.00 (Low) Time Sensitivity: 0.95 (High) 0.86 (Moderate) Predictability: 0.71 (High) 0.07 (Low) Target Injury Score: 2.35 0.93

*Severity Score = Log-normalized Co-Injury adjusted Mortality Risk Ratio (MRRMAIS)

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Conclusions

• Current AIS-based severity metrics not

created for children & may not capture all aspects of injury

• Evaluation of Severity, Time

Sensitivity and Predictability provide more robust assessment of injury

• Future applications will involve

integration of Target Injury Scores into an Advanced Automatic Crash Notification Algorithm

Time- Sensitivity Predictability

Severity

Thank you! Questions?

BACK-UP SLIDES

Determining the Most Frequent Injuries

Weighted Injury Count Cumulative Percent

0% 20% 40% 60% 80% 100% 120% 10000 20000 30000 40000 50000 60000

1 51 101 151 201 251 301 351 401 451 501 551

0 50 100 150 200 250 200 350 400 450 500 550

95%: 195 Unique Injuries 100%: 551 Unique Injuries 2000-2011

Excluded 2009-2011 with MY > 10 yrs (injury data missing)

Inclusion Criteria

• Age < 19yo
• AIS 2+ Injuries

NASS 2000-2011 AIS 2+ Injury Ranking

Mortality Risk Ratios (MRR)

Deaths Total Injured MRR = = = 0.20 20 100 = MAIS Adjusted MRR (MRRMAIS) Deaths w/ MAIS = Injury’s AIS Total Injured w/ MAIS = Injury’s AIS

AIS 2 Injury: 60 of 100 Injured w/ MAIS =2

= = 0.12 5 Deaths (MAIS = 2) 60 Injured (MAIS =2)

Excludes patients w/ higher AIS co-injuries  1st component of severity score = MRRs  Year 1 calculated MRR and MRRMAIS using 2002-2006 data  Year 2 incorporated NTDB 2007-2011 as well

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MRRMAIS

MRR

0-4 years: 10-14 years: 15-18 years:

MRRMAIS

MRR MRR

MRRMAIS

MRR

Distributions of MRR and MRRMAIS by Age Group

• MRR and MRRMAIS

analyses using increased sample sizes

• Distributions of data

remain right-skewed

5-9 years:

MRRMAIS

MRR Severity vs AIS Severity

• There is an overall positive correlation between AIS Severity and

MRR/MRRMAIS.

• Within each AIS Severity, there, is large variation in MRR & MRRMAIS
• There are some lower severity AIS scores that have higher MRRs &

MRRMAIS than higher severity AIS Scores.

y = 0.0471x2 - 0.2258x + 0.312 R² = 0.63 y = 0.1008x - 0.1844 R² = 0.481

0.2 0.4 0.6 0.8 1 1.2 2 3 4 5 6

MRR AIS Severity

MRR by AIS Severity, 0-18 years

y = 0.0593x2 - 0.3058x + 0.3803 R² = 0.7999 y = 0.1053x - 0.2446 R² = 0.5517

• 0.2

0.2 0.4 0.6 0.8 1 1.2 2 3 4 5 6

MRR MAIS AIS Severity

MRRMAIS by AIS Severity, 0-18 years

Plots for 0-18 years shown below. Plots for other pediatric subsets appear similar.

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MRRMAIS 0-4 Years MRRMAIS >/=19 Years

0.0001 0.001 0.01 0.1 1 0.0001 0.001 0.01 0.1 1

MRRMAIS 5-9 Years MRRMAIS >/=19 Years

Comparing Mortality between Adults & Children

 MRRMAIS for an injury in each pediatric group of note is plotted against the MRRMAIS of that injury in the >/= 19 year (adult) group.  Injuries are categorized by body region as noted in the legend.  Injuries appearing below the equivalency line demonstrated a greater MRRMAIS for adults than for the stratified pediatric age group of note

Equivalency Line 0.000 0.000

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 MRRMAIS for an injury in each pediatric group of note is plotted against the MRRMAIS of that injury in the >/= 19 year (adult) group.  Injuries are categorized by body region as noted in the legend.  Injuries appearing below the equivalency line demonstrated a greater MRRMAIS for adults than for the stratified pediatric age group of note

Equivalency Line

0.0001 0.001 0.01 0.1 1 0.0001 0.001 0.01 0.1 1

MRRMAIS 10-14 Years MRRMAIS >/= 19 Years

0.0001 0.001 0.01 0.1 1 0.0001 0.001 0.01 0.1 1

MRRMAIS 15-18 Years MRRMAIS >/= 19 Years

Comparing Mortality between Adults & Children

0.000 0.000

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 Mimicking what was done in Potoka et al, we chose to “dichotomize” FIM Scores

Disability Risk Ratios # Disabled after injury Total # with injury = DRR

FIM FEED FIM LOCOMOT FIM EXPRESS If any of these were 1 or 2 then patient labeled as “Disabled” (obviously we would explain there are diff levels of disability but all of these patients had some level of more than mild disability at discharge) If all are 3 or 4 then patient is “Not disabled”

For each AIS code, we then calculated the following: (Disability Risk Ratio)

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Calculation of Time Sensitivity Scores

Urgency Multiplier = [0.1 * Urgency Score] + -0.3 TS Score = TC Dec Score + [ Urgency Muliplier ∗ TC Dec Score] ( )

For each injury within each age group, the following were calculated: 1. TC Dec Score = Mean of all TC decision responses (0= Non-TC, 1= TC)

• 2. Urgency Score = Mean of all Urgency Score responses (1 -5)

To Calculate the Time Sensitivity (TS) Score, we first calculated an urgency multiplier:

Urgency score of 5 shifts up 20% Urgency score of 1 shifts down 20%

The TS Score is then calculated based on the following equation:

Severity Score (MRR*) Time Sensitivity (Urgency + Trauma Decision) Predictability (Occult + Transfer Score

Target Injury Score Target Injury Score (TIS), 0-3

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*Log-normalized, future will add evaluation of disability as well