Diagnostic accuracy and reproducibility in the interpretation of Ottawa ankle and foot rules by specialized emergency nurses

Abstract

Objectives The ED is often confronted with long waiting periods. Because of the progressive shortage in general practitioners, further growth is expected in the number of patients visiting the ED without consulting a general practitioner first. These patients mainly present with minor injuries suitable for a standardized diagnostic protocol. The question was raised whether these injuries can be treated by trained ED nurses (specialized emergency nurses [SENs]). The aim of this study was to evaluate the diagnostic accuracy and reproducibility of SENs in assessing ankle sprains by applying the Ottawa Ankle Rules (OAR) and Ottawa Foot Rules (OFR). Methods In a prospective study, all ankle sprains presented in the ED from April to July 2004 were assessed by both a SEN and a junior doctor (house officer [HO]) randomized for first observer. Before the study, SENs were trained in applying OAR and OFR. In all patients, radiography was performed (gold standard). The diagnostic accuracy for the application of OAR and OFR was calculated for both groups and was compared using z statistics. Furthermore, from the paired results, reproducibility was calculated using κ statistics. Results In total, 106 injuries were assessed in pairs, of which 14 were ultimately found to concern acute fractures (prevalence, 13%). The sensitivity for the SEN group was 0.93 (95% confidence interval [CI], 0.64-1.00) compared with 0.93 (95% CI, 0.64-1.00) for the HO group (no significance [ns]). The specificity of the nurses was 0.49 (95% CI, 0.38-0.60) compared with 0.39 (95% CI, 0.29-0.50) for the doctors (ns). The positive predictive value for the SEN group was 0.22 (95% CI, 0.13-0.35) compared with 0.19 (95% CI, 0.11-0.31) for the HO group (ns). The negative predictive value for the nurses was 0.98 (95% CI, 0.87-1.00) compared with 0.97 (95% CI, 0.84-1.00) for the doctors (ns). The interobserver agreement for the OAR and OFR subsets was κ = 0.38 for the lateral malleolus; κ = 0.30, medial malleolus; κ = 0.50, navicular; κ = 0.45, metatarsal V base; and κ = 0.43, weight-bearing. The overall interobserver agreement for the OAR was κ = 0.41 and κ = 0.77 for the OFR. Conclusion Specialized emergency nurses are able to assess ankle and foot injuries in an accurate manner with regard to the detection of acute fractures after a short, inexpensive course.