Objectives – To ascertain the annual number of users who were discharged home after visits to the emergency department, grouped by age, gender and number of visits during the calendar year, and to assess whether an increasing number of visits to the department predicted a higher mortality.

Methods – This is a retrospective cohort study, at the emergency department of Landspitali University Hospital, Reykjavik capital city area, Iceland. During the years of 1995 to 2001 19259 users visited the emergency department, and were discharged home and they were follow-up for cause specific mortality through a national registry. Standardised mortality ratio, with expected number based on national mortality rates was calculated and hazard ratios according to number of visits per calendar year using time dependent multivariate regression analysis were computed.

Results – The annual increase of visits to the emergency department among the patients discharged home was seven to 14 per cent per age group during the period 1995 to 2001, with a highest increase among older men. The most common discharge diagnosis was the category Symptoms, signs and abnormal clinical and laboratory findings not elsewhere classified. When emergency department users were compared with the general population, the standardised mortality ratio was 1.81 for men and 1.93 for women. Among those attending the emergency department two times, and three or more times in a calendar year, the mortality rate was higher than among those coming only once in a year. The causes of death which led to the highest mortality among frequent users of the emergency department were neoplasm, ischemic heart diseases, and the category external causes, particularly drug intoxication, suicides and probable suicides.

Conclusions – The mortality of users of the emergency department who had been discharged home turned out to be higher than that of the general population. Frequent users of the emergency department had a higher mortality than those visiting the department no more than once in a year. Since the emergency department serves general medicine and surgery patients, not injuries, the high mortality due to drug intoxication, suicide and probable suicide is notable. Further studies are needed into the diagnosis at discharge of those frequently using emergency departments, in an attempt to understand and possibly prevent this mortality