Post on 09-Feb-2017
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