Frequent users of emergency care are more than twice as likely as infrequent users to die, be admitted to hospital, or require other outpatient treatment, concludes an analysis of the available evidence, published online in Emergency Medicine Journal.

The available evidence suggests that frequent users account for up to one in 12 patients seeking emergency department care, and for around one in four of all visits.

The authors base their findings on a thorough search of seven electronic databases of relevant research relating to the frequency and outcomes of emergency department use by adults.

Out of a total of more than 4000 potential studies, 31 relevant pieces of research published between 1990 and 2013 were included in the final analysis.

Frequent users were variously defined as visiting emergency care departments from four or more times up to 20 times a year.

Among the seven studies looking at deaths, the analysis showed that frequent attenders at emergency care departments were more than twice as likely to die as those who rarely sought emergency care.

Most of the studies included hospital admission as an outcome, and these showed that frequent users were around 2.5 times as likely to be admitted as infrequent users.

Ten studies looked at use of other hospital outpatient care, and these showed that frequent users were more than 2.5 times as likely to require at least one outpatient clinic after their visit to the emergency care department.

"Our results suggest that, despite heterogeneity, frequent users are a distinct and high risk group," write the authors, adding that they might benefit from a more targeted proactive approach.

But the lack of any consensus as to what constitutes a frequent user is striking, they emphasize, and this makes it difficult to permit comparison and come up with potentially generalisable recommendations. This needs addressing as a matter of urgency, they say.