Table 3.

Predictive characteristics of chronic frequent ED use

Reference	Authors	Definition of chronic use	Prevalence % of patients (% of total ED visits)	Predictive factors
[7]	Andrén et al.	4 or more ED visits per year over a 3 year period	Year 1 : 31 % Year 2 : 19 %	Previous ED visits, contact with psychiatric care, living alone and perceived loneliness
[36]	Billings et al.	5 or more ED visits per year over a 3 year period	1.2 % (10,9 %)	77,9 % had higher levels of chronic illnesses 58,8 % had a history of substance abuse 72,3 % had a history of mental illness48, 9 % had a history of both substance abuse and mental illnessa
		5 or more ED visits per year over a 5 year period	0.8 % (8,4 %)
		3 or more ED visits per year over a 3 year period	3.5 % (19,2 %)
		3 or more ED visits per year over a 5 year period	1.7 % (12,1 %)
[38]	Rask et al.	More than 10 subsequent ED visits (2 year period)	16,6 % (65,5 %)	At least one hospitalization and at least one primary care visit
[39]	Okuyemi et al.	3 or more ED visits per year over a 3 year period	9 to 11 % (between 25 and 30 %)	Being a frequent ED user during the previous year is an independent predictor of frequency of use during the following year

^aAll predictive factors found using regression model for patients visiting the ED 3 or more times during the index year