Opium Consumption and the Risk of Traffic Injuries in Regular Users: A Case-Crossover Study in an Emergency Department

Abstract

Objective. The cause-specific annual death rate due to traffic injuries is around 30 in 100,000 in Iran. On the other hand, this country has the highest proportion of opiate users in the world. Little is known about the transient effect of opium on traffic injuries. The objective of this study was to explore the effect of opium consumption on traffic injuries in drivers who use opium. Methods. Seventy-five regular opium users who suffered traffic injuries were studied in a case-crossover investigation. The study subjects had been admitted to the single trauma emergency department in Kerman, a city in southeast Iran. The relative risk (RR) of short-term opium effect was estimated by considering frequency of driving after opium consumption during 6 hours before the accident in comparison to the usual frequency of driving after opium consumption by the same persons. Stratified data analysis was performed by the Mantel-Haenszel method. Results. The opium consumption of drivers up to 6 hours before the accident was associated with an increased RR = 3.2, 95 percent confidence interval (CI): 1.9, 5.4. The third hour after consumption had the greatest magnitude of effect considering RR = 4.29, 95 percent CI:2.65, 6.95. Conclusions. These results suggest a heightened risk of traffic injuries after opium consumption in regular users. The RR in the third hour after consumption could be explained by considering the greater probability of driving compared to the immediate hours after use, rather than peak effect time of opiates. The results indicate necessity of regular assessment of all common drivers, especially truck and bus drivers, regarding use of opium.