Diagnostic performance of the Bernese versus Ottawa ankle rules: Results of a randomised controlled trial

Abstract

Purpose: The Ottawa ankle rules (OAR) brought about a reduction of radiographs on the Emergency Department (ED). However, still 50% of patients with ankle injuries undergo unnecessary radiography. Compared to the OAR, the Bernese ankle rule (BAR) has an acclaimed 84% reduction in radiography without loss of sensitivity. The primary aim of this study was to compare the diagnostic accuracy and reproducibility of both rules. Furthermore, the ability of triage nurses to accurately interpret the BAR was assessed.

Methods: Participants were assessed by both the ED resident and the triage nurse, applying the OAR and the BAR. After standardised data collection, ankle and foot radiographs were performed in all patients. Sensitivity and specificity of both tests applied by both observers were obtained and compared by McNemar's test. Reproducibility was calculated with Cohen's kappa.

Results: A total of 203 patients with ankle trauma were included. For the OAR obtained by the ED residents, the sensitivity and specificity were 0.97 and 0.29, respectively. For the BAR, the sensitivity and specificity of the ED residents were 0.69 and 0.45, respectively. For the triage nurses, the OAR sensitivity and specificity were 0.86 and 0.25, respectively. The BAR sensitivity and specificity for the nurses were 0.86 and 0.40, respectively. The reproducibility of the OAR was 0.45, and for the BAR, it was 0.48.

Conclusion: Both rules showed comparable reproducibility. Although the BAR showed a superior specificity compared to the OAR, its sensitivity was too low to promote clinical use. The triage nurses demonstrated too low sensitivity on both rules to allow safe application. Therefore, the OAR remain the decision rules of choice for ankle injuries despite its modest 'ruling out' capacity.

Keywords: Ankle distortion; Bernese ankle rule; Diagnostic accuracy; Ottawa ankle rules; Reproducibility.