Diagnostic accuracy of the Ottawa ankle rule to exclude fractures in acute ankle injuries in adults: a systematic review and meta-analysis

Background: Ankle traumas are common presenting injuries to emergency departments in Australia and worldwide. The Ottawa Ankle Rules (OAR) are a clinical decision tool to exclude ankle fractures, thereby precluding the need for radiographic imaging in patients with acute ankle injury. Previous studies support the OAR as an accurate means of excluding ankle and midfoot fractures, but have included a paediatric population, report both the ankle and mid-foot, or are greater than 5 years old. This systematic review and meta-analysis aimed to update and assess the existing evidence of the diagnostic accuracy of the Ottawa Ankle Rule (OAR) acute ankle injuries in adults. Methods: A systematic search and screen of was performed for relevant articles dated 1992 to 2020. Prospective and retrospective studies documenting OAR outcomes by physicians to assess ankle injuries were included. Critical appraisal of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Outcomes related to psychometric data were pooled using random effects or fixed effects modelling to calculate diagnostic performance of the OAR. Between-study heterogeneity was assessed using the Higgins I2 test, with Spearman’s correlation test for threshold effect. Results: From 254 unique studies identified in the screening process, 15 were included, involving 8560 patients from 13 countries. Sensitivity, specificity, negative likelihood ratio, positive likelihood ratio and diagnostic odds ratio were 0.91 (95% CI, 0.89 to 0.92), 0.25 (95% CI, 0.24 to 0.26), 1.47 (95% CI, 1.11 to 1.93), 0.15 (95% CI, 0.72 to 0.29) and 10.95 (95% CI, 5.14 to 23.35) respectively, with high between-study heterogeneity observed (sensitivity: I2 = 94.3%, p < 0.01; specificity: I2 = 99.2%, p < 0.01). Most studies presented with low risk of bias and concern regarding applicability following assessment against QUADAS-2 criteria. Conclusions: Application of the OAR is highly sensitive and can correctly predict the likelihood of ankle fractures when present, however, lower specificity rates increase the likelihood of false positives. Overall, the use of the OAR tool is supported as a cost-effective method of reducing unnecessary radiographic referral, that should improve efficiency, lower medical costs and reduce waiting times.