“…12,13,15,25,27,31,32,34,36,37,[39][40][41]45,46,48,49 Other countries represented were Canada, 38,43 the United Kingdom, 16,26,33 Australia, 14,30 Sweden, 17,28,44,47 Scotland, 35 Taiwan, 29 and Switzerland. 42 Overall, studies included a general frequent user population; however, some focused their inclusion on subgroups with psychiatric, mental health or substance abuse comorbidities, 25,26,36,39,43 homeless, low income, unemployed or uninsured/underinsured patients, 13 41 Additional definitions were more than three visits in 6 months, 44 10 visits in 6 months, 35 three visits in 1 month, 37 and three or more visits in 72 hours. 29 Other studies considered the top 30, 33 50, 15 or 100 attendees 36 to be frequent users or allowed staff or investigators to determine inclusion without specified thresholds …”