Transcript Document
Investigating Changes in FatalCrash-Involved Drivers’ Cannabinoid Prevalence after Passage of Medical Marijuana Laws G. Vanine Guenzburger Scott V. Masten 1 Research & Development Background • Marijuana use affects perception, concentration, decision making, attention, reaction time, and coordination • Marijuana use within 4 hrs. before driving associated with 2-6 times higher risk of crashing • CA first to pass medical marijuana law in the US: o Proposition 215 (1996) – Legalized o Senate Bill 420 (2004) – Operationalized 2 US Medical Marijuana Laws Maryland New Mexico 3 Research Questions 1. Are medical marijuana laws associated with changes in cannabinoid prevalence among drivers involved in fatal crashes in states with such laws? 2. Are changes in prevalence associated with the degree of patients’ accessibility to marijuana? 4 Data Source: Fatality Analysis Reporting System Outcome Measure: Prevalence % of drivers with detected cannabinoids not necessarily impaired Regions studied: 13 states with Medical Marijuana laws Cohorts: Two were studied o All drivers involved in fatal crashes o Fatally-injured drivers Time Period: 1992 – 2009 5 Confounding Variables Driver drug testing regularity in each state o Related to higher cannabinoid prevalence • Increased in CA after marijuana law o Varies greatly from year to year National trend for drivers’ cannabinoid prevalence oIncreased 1% to 4% in non-medical marijuana states from 1992-2009 6 Drug testing and Cannabinoid Prevalence among CA Drivers in fatal crashes State Cannabinoid Prevalence Percentage of Fatal-Crash-Involved Drivers 50 State Drug Testing SB 420 Prop 215 (2004) (1996) 45 National Cannabinoid Prevalence 40 35 30 25 20 15 10 5 CA Testing increased CA Marijuana prevalence did not differ from National Trend Step change and plateau with operationalization (2.1%) National Trend approaching California’s 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 20097 Year All Fatal-Crash-Involved Drivers State California % step change in prevalence 2.1* Access Rankings (most to least) 1 Michigan -0.1 2 Rhode Island -2.5 3 Maine 0.1 4 Montana -0.6 5 Colorado -0.2 6 New Mexico 0.1 7 Hawaii 6.0* 8 Washington 3.4* 9 Nevada 1.2 10 Oregon 0.1 11 Vermont 0.0 12 Alaska -2.2 13 Maryland 0.1 14 8 Drug Testing and Cannabinoid Prevalence Killed CA Drivers 100 State Cannabinoid Prevalence National Cannabinoid Prevalence SB 420 Prop 215 90 Percentage of Fatally-Injured Drivers State Drug Testing (2004) (1996) 80 70 60 CA Testing increased 50 40 30 20 10 CA Marijuana prevalence did not differ from National Trend Step change and plateau with Operationalization (5.7%) National Trend Approaching California’s 0 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Year 9 Fatally-Injured Drivers State % step change in prevalence Access Rankings (most to least) California 5.7* 1 Michigan 0.4 2 Rhode Island -4.6 3 Maine 0.0 4 Montana -1.4 5 Colorado -0.5 6 New Mexico 1.6 7 Hawaii 9.6* 8 Washington 4.6* 9 Nevada 2.0 10 Oregon -1.2* 11 Vermont -1.0 12 Alaska -1.5 13 Maryland 0.1 14 10 Conclusions Implementation of medical marijuana laws was associated with changes in cannabinoid prevalence among drivers involved in fatal crashes in only three states o California o Hawaii o Washington Increases were step changes, not upward trends Changes in prevalence were not associated with ease of patient access to marijuana Note: Volatility of driver drug testing may be masking law effects in the other states 11 Recommendations • Driver drug testing should be standardized and more consistent • Next: Investigate relationship of driver marijuana use to crash contribution 12 Questions / Follow-up Contact: Patrice Rogers, California DMV Research and Development Branch—DUI Unit Manager [email protected] G. Vanine Guenzburger DMV Research and Development Branch—Project Leader [email protected] Research & Development Branch 13