The NY Times On Marijuana And Emergency Department Admissions

The Times misses part of the story when they write:
"Marijuana was found -- alone or in combination with other drugs -- in more than 455,000 patients visiting emergency rooms in 2011."

A drug mention does not mean that the drug is what caused the visit. Rather, it simply means that the substance was in their system. Arguably, drug mentions in an emergency room may have some meaning yet unless the drug is at fault, those mentions are merely an indicator of prevalence of use:
"DAWN captures drugs that are explicitly named in the medical record as being involved in the ED visit. The relationship between the ED visit and the drug use need not be causal. That is, an implicated drug may or may not have directly caused the condition generating the ED visit; the ED staff simply named it as being involved." (p. 15)

According to the DAWN report, "Of the approximately 2.5 million drug misuse or abuse ED visits that occurred during 2011, a total of 1,252,500, or just over half (50.9%), involved illicit drugs (Table 4). A majority (56.3%) of illicit drug ED visits involved multiple drugs. Overall, 27.9 percent of visits involving illicit drugs also involved alcohol.
"Cocaine and marijuana were the most commonly involved drugs, with 505,224 ED visits (40.3%) and 455,668 ED visits (36.4%), respectively. Cocaine and marijuana were followed by heroin, at 258,482 ED visits, or 20.6 percent, and then by amphetamines/methamphetamine, at 159,840 visits, or 12.8 percent." (DAWN ED Report 2011, p. 25)


The New York Times, "What Science Says About Marijuana," by Philip M. Boffey, July 30, 2014.
Substance Abuse and Mental Health Services Administration, Drug Abuse Warning Network, 2011: National Estimates of Drug-Related Emergency Department Visits. HHS Publication No. (SMA) 13-4760, DAWN Series D-39. Rockville, MD: Substance Abuse and Mental Health Services Administration, 2013, p. 25 and p. 15.