Risk of injury from alcohol and drug use in the emergency department: A case-crossover study

A substantial literature exists demonstrating the risk of injury from alcohol, but less is known about the association of alcohol in combination with other drugs and injury. This study examined the risk of injury associated with alcohol and drug use prior to the injury event. Case-crossover analysis was used to estimate the relative risk (RR) of injury due to alcohol use alone, compared to alcohol in combination with other drug use in a sample of emergency department (ED) injured patients from two sites in Vancouver, BC (n=443). Alcohol and drug use in the six hours prior to injury was compared with the patient's use of these substances during the same six-hour period the day prior and the week prior to injury. Using multiple matching for the two control time periods, RR of injury was significantly related to both alcohol use (RR = 3.3) and to alcohol combined with drug use (RR=3.0), but not to drug use alone. Effect modification was found only for alcohol combined with drug use, with a significant increase in injury risk (p=.087) for those over 30. Although no difference in elevated risk of injury was found for alcohol use alone compared to alcohol used with other drugs, the literature suggests that alcohol in combination with some drugs may be important to consider in injury risk. Numbers here did not permit analysis by specific alcohol-drug combinations. Findings suggest the need for future research with larger samples of substance using patients.