Effect of the Low Risk Ankle Rule on the frequency of radiography in children with ankle injuries

Background:

The Low Risk Ankle Rule is a validated clinical decision rule that has the potential to safely reduce radiography in children with acute ankle injuries. We performed a phased implementation of the Low Risk Ankle Rule and evaluated its effectiveness in reducing the frequency of radiography in children with ankle injuries.

Methods:

Six Canadian emergency departments participated in the study from Jan. 1, 2009, to Aug. 31, 2011. At the 3 intervention sites, there were 3 consecutive 26-week phases. In phase 1, no interventions were implemented. In phase 2, we activated strategies to implement the ankle rule, including physician education, reminders and a computerized decision support system. In phase 3, we included only the decision support system. No interventions were introduced at the 3 pair-matched control sites. We examined the management of ankle injuries among children aged 3–16 years. The primary outcome was the proportion of children undergoing radiography.

Results:

We enrolled 2151 children with ankle injuries, 1055 at intervention and 1096 at control hospitals. During phase 1, the baseline frequency of pediatric ankle radiography at intervention and control sites was 96.5% and 90.2%, respectively. During phase 2, the frequency of ankle radiography decreased significantly at intervention sites relative to control sites (between-group difference −21.9% [95% confidence interval [CI] −28.6% to −15.2%]), without significant differences in patient or physician satisfaction. All effects were sustained in phase 3. The sensitivity of the Low Risk Ankle Rule during implementation was 100% (95% CI 85.4% to 100%), and the specificity was 53.1% (95% CI 48.1% to 58.1%).

Interpretation:

Implementation of the Low Risk Ankle Rule in several different emergency department settings reduced the rate of pediatric ankle radiography significantly and safely, without an accompanying change in physician or patient satisfaction. Trial registration: ClinicalTrials.gov, no. {"type":"clinical-trial","attrs":{"text":"NCT00785876","term_id":"NCT00785876"}}NCT00785876.Pediatric ankle injuries result in more than 2 million emergency department visits in Canada and the United States each year (Jeanette Tyas, Canadian Institute of Health Information: unpublished data, 2007).^1,2 Radiographs are ordered for 85%–95% of these children,³ although only 12% of these reveal a fracture.⁴ Thus, radiography is unnecessary for most children’s ankle injuries, and these high rates of radiography needlessly expose children to radiation and are a questionable use of resources.The Low Risk Ankle Rule has 100% sensitivity with respect to identifying clinically important pediatric ankle fractures and has the potential to safely reduce imaging by about 60%.⁴ When the application of the rule suggests that radiography is not needed, it has been shown that any fractures that might be missed are clinically insignificant and can be safely and cost-effectively managed like an ankle sprain, with superior functional recovery.⁵ Finally, the Low Risk Ankle Rule has been shown to have excellent acceptability when tested on emergency physicians.⁶The main objective of this study was to implement the ankle rule in several different emergency department settings using a multimodal knowledge translation strategy and to evaluate its impact on the frequency of radiography in children presenting with acute ankle injuries.