Table 2 Study characteristics summary

Study types

 Single-arm trials

16

 RCT

5

 Non-RCT

1

Decision rules

 Ottawa Ankle Rules

10

 Canadian CT Head Rule

5

 Ottawa Knee Rule

3

 NEXUS guidelines^a

3

 Canadian C-Spine rules^a

2

Outcomes of interest

 Overall imaging use

14

 Use of rules

10

 Indicated or non-indicated imaging

6

 Knowledge of the rules

2

Countries

 USA

10

 Canada

6

 UK

2

 Australia

2

 France

1

 Ireland

1

Hospital settings

 Community/tertiary/teaching hospital EDs,

17

 Acute care centres

3

 Major trauma centres, and

2

Participants

 Clinicians

1271^b

 Patients

35,010^b

Clinician types

 ED physicians

13

 Junior doctors

10

 ED nurse practitioners

6

 Physician assistants

4

 ED nurses

4

 Trauma team leaders

1