Characteristics and trends of emergency patients with drug overdose in Osaka.

Aim: Drug overdose is an important issue in emergency medicine. However, studies covering overdose patients transported by ambulance have not been sufficiently carried out. We attempted to clarify problems of suspected drug overdose patients transported by ambulance.

Methods: This is a prospective population-based cohort study. Data were collected by emergency medical service crews in Osaka City, Japan, between January 1998 and December 2010.

Results: Drug overdose cases increased annually from 1,136 in 1998 to 1,822 in 2010 ( < 0.0001 for trend). In these cases, the dominant age range was between 16 and 40 years and the age distribution did not change over time. The age of non-overdose cases increased ( < 0.0001 for trend), with patients aged ≥66 years becoming most common in recent years, reflecting the aging of society. Males comprised most non-overdose patients, but the percentage of females increased annually ( < 0.0001 in trend). Females comprised approximately 70% in overdose cases annually throughout the study period. The duration from the emergency call to the arrival at the hospital for overdose patients has increased markedly in recent years. It also takes more time to obtain acceptance from hospitals to care for patients of suspected overdose.

Conclusion: The characteristics of drug overdose patients are clearly different from those of non-overdose patients. Recent trends of drug overdose patients indicate the accelerated burden on emergency medical services system.