62% increase in emergency department visits involving marijuana [2004–2011],19 and a 3-fold increase in cannabis involvement in fatal car crashes [1999–2010]).17 The consistency of the NESARC/NESARC-III findings with these other national increases supports the validity of the NESARC/NESARC-III findings. Further, NSDUH prevalence estimates before 2002 cannot be used in time trend analyses owing to changes in NSDUH methods, and no other sources of information are available on long-term time trends in the prevalence of past-year DSM-IV marijuana use disorder. Therefore, the combined information from the earlier 1991–1992 National Longitudinal Alcohol Epidemiologic Survey/NESARC comparison28 with the present NESARC/NESARC-III comparison represents a unique resource for examining change in prevalence of marijuana use disorders from studies with similar methods and measures during a period spanning 20 years.
