To determine the effect of triage nurse initiated radiographs using the Ottawa Ankle Rules (OAR) on emergency department (ED) throughput. We hypothesized OAR use would reduce median ED length of stay (LOS) by 25 minutes or more.

A randomized controlled trial was conducted at a tertiary centre ED with an annual census of over 90,000 patients. Adult patients presenting within 10 days of isolated blunt ankle trauma were eligible. Participants were randomly assigned to standard triage or OAR application by 15 explicitly trained triage nurses. Our primary outcome was ED LOS. Secondary outcomes included triage nurses' and patients’ satisfaction. A power calculation indicated 142 patients were required. The Mann-Whitney U test was used to compare the medians between the two groups.

Of 176 patients with blunt ankle injury screened, 146 were enrolled (83.0%); baseline characteristics in the two groups were similar. The median/mean ED LOS in the control and OAR groups were 128/143 minutes and 108/115 minutes respectively (median difference 20 minutes; p=0.003). Agreement in OAR use between emergency physicians and nurses was moderate (kappa 0.46/0.77 for foot/ankle rule components), and satisfaction of both nurses and participants was high.

Triage nurse initiated radiography using OAR leads to a statistically significant decrease of 20 minutes in the median ED LOS at a tertiary care centre. The overall impact of implementing such a process is likely site-specific, and the decision to do so should involve consideration of the local context.