STOP WATCH TESTINGAn analysis into the use of a new testing technique to identify and treat concussions

By Peter Eggleston ConnorData provided by

Southern Oregon OrthopedicsA Graduate Thesis from

Southern Oregon University

TERMINOLOGY

Reaction TimeHealthy / Injured / Recovering

Days Since Injury (or: Recovery Time)

Symptom Score

HISTORY

• Prior to 2001: Concussion detection had little empirical evidence supporting it.

• 2001-2012: American Academy of Neurology (AAN) creates guidelines for more globally accessing concussion risks in athletes.

• 2013: An update came out pointing towards evidence that having a concussion made future concussions more likely.

OBJECTIVES

• Identify changes between healthy and injured reaction times

• Determine a concussion recovery rate based on reaction time

• Identify significant symptom scores over course of recovery

DATA COLLECTION – HEALTHY AND INJURY FORM

DATA COLLECTION – RECOVERING FORM

DATA ORGANIZATION

DESCRIPTIVE ANALYSIS

DESCRIPTIVE ANALYSIS – RECOVERY TIME

n = 39

Mean:8.2 days

Standard Deviation:5.3 days

90th Percentile:~11 days

DESCRIPTIVE ANALYSIS – HEALTHY REACTION TIME

Mean:0.18 sec

Standard Deviation:0.03 sec

DESCRIPTIVE ANALYSIS – HEALTHY REACTION TIME IN CONCUSSED PLAYERSMean:

0.18 secStandard Deviation:

0.02 sec

Hypothesis Test All vs Concussed Healthy Reaction Timesp-value:

0.16Conclusions:

Accept Null

DESCRIPTIVE ANALYSIS – INJURED REACTION TIME Mean:

0.27 secStandard Deviation:

0.10 sec

Hypothesis Test Healthy vs Injured Reaction Time in Concussed Athletes p-value:

~1Conclusion:

Reject Null

DESCRIPTIVE ANALYSIS – REACTION TIME

DIFFERENCES

Mean:.088 sec

Standard Deviation:.098 sec

DESCRIPTIVE ANALYSIS – REACTION TIME RATIOS

Mean:1.49

Standard Deviation:0.52

COMPAREDAYS TO REACTION TIME

EXPONENTIAL MODELING:DIFFERENCE 𝑦=(𝑐−h)𝑒𝛽𝑡+hy: The reaction time at t days since injury

c: The reaction time at the time of injury

h: The healthy reaction time

β: The rate of decay in the reaction time during recovery

t: The number of days since the concussion injury

EXPONENTIAL MODELING

𝑦=(𝑐−h)𝑒𝛽𝑡+h

Purple:β = .01

Red:β = .2

Blue:β = 1

EXPONENTIAL MODELING: DIFFERENCES

𝑦 𝑖=(𝑐 𝑖−h 𝑖¿𝑒−𝛽 𝑡+h𝑖

EXPONENTIAL MODELING: DIFFERENCES

Where:i: Index for patient histories (1 to 39)ŷ: The predicted reaction time at t days since injury

Objective: Find the β that minimizes

∑𝑖

𝑛

∑𝑗

𝑚𝑖

( 𝑦 𝑖− ŷ𝑖 )2

PREDICTIVE MODELUSINGDIFFERENCES

𝑦=(𝑐−h )𝑒−0.5441 𝑡+h

With β selected as 0.5441 is optimized at 0.62

PREDICTIVE MODEL USING DIFFERENCES

Can be transformed into: 𝑡 𝑦 ,𝑖=¿¿Where 𝑘=𝑦−h𝑖

PREDICTIVE MODEL USING DIFFERENCE BETWEEN HEALTHY AND INJURY

𝑡𝑦 ,𝑖=¿¿Optimal k:0.0014

Mean:6.97 Days

Standard Deviation:1.52 Days

EXPONENTIAL MODELING: RATIO

𝑦 𝑖

h 𝑖=(

𝑐 𝑖

h𝑖−1)𝑒−𝛽 𝑡+1

EXPONENTIAL MODELING: RATIO

Objective: Find the β that minimizes

∑𝑖

𝑛

∑𝑗

𝑚𝑖

( 𝑦 𝑖

h𝑖−^(𝑦 𝑖

h 𝑖))

2

Where: : Is the predicted ratio

PREDICTIVE MODEL USING RATIOS

With β selected as 0.5696 is optimized at 0.43

𝑦 𝑖

h 𝑖=(

𝑐 𝑖

h𝑖−1)𝑒− 0.5696𝑡+1

PREDICTIVE MODEL USING RATIOS

To predict days until RTP:

Where𝑝=

𝑦 𝑖

h𝑖−1

PREDICTIVE MODEL USING RATIOS OF HEALTHY TO INJURY

Optimal p:0.008

Mean:6.97 Days

Standard Deviation:1.50 Days

SYMPTOMS Blurry Vision Concentration Dizziness Fatigue Headache Heightened Feelings Light Sensitivity Loss of Balance Memory Loss Nausea Noise Sensitivity Sleeping Habits

SYMPTOMS COMPARED TO DAYS SINCE INJURYHEADACHE EXAMPLE

SYMPTOM LINEAR MODELING: SINGLE DESCRIPTIVE VARIABLE

Where:y: Represents the response variable, days since

injury x: Represents the predictor variable, a symptom: Is the value of y when x is zero: The amount y changes when x increases by 1

𝑦=𝑏0+𝑏1𝑥

SYMPTOM LINEAR MODELING: MULTIPLE DESCRIPTIVE VARIABLES

Where:n: Is the number of predictor variables used in the

model: Is a predictor variable value, where are

symptoms: The amount y changes when increases by 1

𝑦=𝑏0+𝑏1𝑥1+𝑏2 𝑥2+...+𝑏𝑛𝑥𝑛

SYMPTOMS COMPARED TO DAYS SINCE INJURY

ANALYSIS OF VARIANCE(ANOVA)

• Identify Predictor Variables Independently in Multivariable Experiments

• Assess Explained and Residual Variation of Response Variable

• Determine Significance of Predictor Variables on Response Variable

SYMPTOMS COMPARED TO DAYS SINCE INJURYANOVA

SYMPTOMS COMPARED TO REACTION TIMEHEADACHE EXAMPLE

SYMPTOMS COMPARED TO REACTION TIME

SYMPTOMS COMPARED TO REACTION TIMEANOVA

CONCLUSIONS:DETERMINING A CONCUSSION OFF OF STOP WATCH TESTINGThe reaction times taken after injury were significantly different from those of healthy times taken at the beginning of the season.

CONCLUSIONS:RETURN TO PLAY

𝑡𝑦 ,𝑖=¿¿Best Calculator:

Roughly 97.5% of cases recover in 10 Days.

CONCLUSIONS:CONCUSSION SYMPTOMS

Headache, dizziness, fatigue, heightened feelings, and feeling nauseas showed significance when looking at reaction time.

Headache showed significance when looking at days since injury.

FURTHER RESEARCH

Unconscious Incidents

Multiple Concussions

Correlation Coefficients in Linear Analysis

Larger Data Set