Evaluation of Drug Recognition Expert Reports in Marijuana Cases Brianna Peterson, Ph.D. and Rod Gullberg, M.S. Washington State Patrol September 20, 2011
Dec 31, 2015
Evaluation of Drug Recognition Expert Reports in Marijuana Cases
Brianna Peterson, Ph.D. and Rod Gullberg, M.S.Washington State Patrol
September 20, 2011
Goal of study
• Determine if DRE indicators for cannabis are present in cases with THC detected
• Compare indicators for subjects with active THC versus THC-COOH only
size
HorizontalGaze Nystagmus
VerticalGazeNystagmus
Lack ofConvergence
Pupil
Reactionto light
Pulse
BloodPressure
Body Temp
Depressants Inhalants DissociativeAnesthetics
Stimulants Hallucinogens NarcoticAnalgesics
Cannabis
Present Present Present None None None
Present Present Present None None None
Present Present Present None None None
Normal Normal Normal Dilated Dilated Constricted
Slow Slow Normal Slow Normal Little to none
Down Up Up Up Up Down
Down Up/Down Up Up Up Down
Normal Up/Down/Normal
Up
None
None
Present
Dilated
Normal
Up
Up
Normal Up Up Down
DRE Matrix
DRE indicators for cannabis category
• Lack of convergence (LOC) present• Pupil size normal to dilated• Elevated pulse rate• Elevated blood pressure
• Horizontal gaze nystagmus (HGN) not present• Vertical nystagmus (VGN) not present• Reaction to light is normal• Body temperature is normal
THC pharmacokinetics
• Highly lipid soluble
• Short half-life– 3 hrs post smoking, THC in serum <5 ng/mL
• Main metabolite: 11-nor-9 carboxy-THC (THC-COOH)
Methodology• DRE cases from 2007-2009; blood sample
analyzed• Tested for volatiles by Headspace Gas
Chromatography• EMIT drug screen
– Cannabinoids cut off = 10 ng/mL THC-COOH
• THC confirmation by GC/MS (SIM mode)– Limits of Detection
• THC = 1.0 ng/mL• THC-COOH = 5.0 ng/mL
Cases that were only positive for THC or THC-COOH
Subjects• THC/THC-COOH (n=101)
– 93% male– 78% Caucasian– Average age: 24 (range: 16-70)
• THC-COOH only (n=147)– 79% male– 84% Caucasian– Average age: 27 (range: 14-61)
• Not impaired (n=17)– 76% male– 94% caucasian– Average age: 38 (range: 19-74)
147 THC/THC-COOH cases
5 10 15 20 30 60 90 120 150 180 210More0
20
40
60
THC-COOH concentration
ng/mL
Fre
qu
ency
Mean = 74.1; median = 61.7
1 2 3 4 5 10 20 30 More0
20
40
60
THC concentration
ng/mL
Fre
qu
ency
Mean = 7.3; median = 5.7
101 THC-COOH only cases
5 10 15 20 30 60 90 120 150 180 210More0
1020
3040
THC-COOH concentration
ng/mL
Fre
qu
ency
Mean = 16.6; median = 13.5
Results
Lack of convergence
*p=0.003*p=0.003
0
10
20
30
40
50
60
70
YesNo
THC/THC-COOH
Pe
rce
nta
ge
THC-COOH
*
*p=0.003
Normal range: 2.5 – 5.0 mm
Average pupil size: Room light
0 10 20 30 40 50 60 70 80 900
1
2
3
4
5
6
7
8
9
10
THC/THC-COOH
THC-COOH
ng/mL
56%, 61% above normal range
Average pupil size: Dark
Normal range: 5.0 - 8.5 mm
0 10 20 30 40 50 60 70 80 900
1
2
3
4
5
6
7
8
9
10
THC/THC-COOH
THC-COOH
ng/mL
60%, 58% above normal range
0 10 20 30 40 50 60 70 80 900
1
2
3
4
5
6
7
8
9
10
THC/THC-COOHTHC-COOH
ng/mL
Average pupil size: Direct light
49%, 47% above normal range
Normal range: 2.0 – 4.5 mm
0 10 20 30 40 50 60 70 8040
50
60
70
80
90
100
110
120
130
140
150
THC/THC-COOHTHC-COOH
ng/mL
Average pulseNormal range = 60-90 bpm
57% above normal range
Systolic blood pressure
0 10 20 30 40 50 60 70 8080
90
100
110
120
130
140
150
160
170
180
190
200
THC/THC-COOHTHC-COOH
ng/mL
Normal range = 120 – 140 mm Hg
45% above normal range
Body Temperature
Normal range = 98.6 ± 1°F
0 10 20 30 40 50 60 70 8095
95.4
95.8
96.2
96.6
97
97.4
97.8
98.2
98.6
99
99.4
99.8
100.2
100.6
101
THC/THC-COOHTHC-COOH
ng/mL
73, 87% in normal range
Not impaired: 17 cases from 2007 - 2009
Summary
Cannabisindicator
THC/THC-COOH
THC-COOH
Not impaired
HGN None 9% 11% 6%
VGN None 0 2% 0
Lack of convergence Present 66% 47% 6%
Pupil Size Normal to dilated
55% 55% 15%
Reaction to light Normal 76% 77% 82%
Pulse Elevated 57% 57% 25%
Blood pressure(Systolic/diastolic)
Elevated 45%/22% 45%/25% 41%/12%
Body Temperature Normal 73% 87% 77%
Summary
THC/THC-COOH
THC-COOH
Bloodshot eyes
Eyelid tremors
2/8 clues on WAT
2/4 clues on OLS
Not impaired
86% 81% 24%
81% 81% 38%
72% 81% 25%
46% 57% 31%
Other indicators
• Romberg test: estimation of 30 seconds– Normal range = 25 to 35 seconds
THC/THC-COOH THC-COOH Not impaired
60% 51% 47%
Other indicators
• Rebound Dilation
• Reaction to light– Normal, slow, little
THC/THC-COOH THC-COOH Not impaired
43% 41% 6%
THC/THC-COOH THC-COOH Not impaired
77% 76% 82%
DRE Opinion
• THC/THC-COOH cases– 97% DRE called cannabis
• Other cases called ‘not impaired’
– 98% subject admitted to marijuana use• THC-COOH only cases
– 97% DRE called cannabis• Stimulant/not impaired
– 88% subject admitted to marijuana use
Conclusions
• DRE matrix is useful tool for predicting marijuana use
• Similar indicators for THC/THC-COOH and THC-COOH cases– Short half-life, long exam process
Beasley et al. study
• Examined which indicators best predict substance (n =742)
• Stimulants versus cannabis– Stimulants: less reddening of eyes and
rebound dilation, more likely to have hippus, injection sites, slow reaction to light
– Cannabis: more likely to have lack of convergence
Toward a More Parsimonious Approach to Drug Recognition Expert Evaluations. Traffic Injury Prevention 2009;10:513-518