two-stage clinical model for screening the suspected cases of acute ischemic stroke in need of imaging in emergency department; a cross-sectional study

Introduction: just as failure to diagnose an acute ischemic stroke (ais) in a timely manner affects the patient's outcome; an inaccurate and misplaced impression of the ais diagnosis is not without its drawbacks. here, we introduce a two-stage clinical tool to aid in the screening of ais cases in need of imaging in the emergency department (ed). methods: this was a multicenter cross-sectional study, in which suspected ais patients who underwent a brain magnetic resonance imaging (mri) were included. the 18 variables from nine existing ais screening tools were extracted and a two-stage screening tool was developed based on expert opinion (stage-one or rule in stage) and multivariate logistic regression analysis (stage-two or rule out stage). then, the screening performance characteristics of the two-stage mode was evaluated. results: data from 803 patients with suspected ais were analyzed. among them, 57.4 % were male, and their overall mean age was 66.9 ± 13.9 years. there were 561 (69.9%) cases with a final confirmed diagnosis of ais. the total sensitivity and specificity of the two-stage screening model were 99.11% (95% ci: 98.33 to 99.89) and 35.95% (95% ci: 29.90 to 42.0), respectively. also, the positive and negative predictive values of two-stage screening model were 78.20% (95% ci: 75.17 to 81.24) and 94.57% (95% ci: 89.93 to 81.24), respectively. the area under the receiver operating characteristic (roc) curve of the two-stage screening model for ais was 67.53% (95% ci: 64.48 to 70.58). overall, using the two-stage screening model presented in this study, more than 11% of suspected ais patients were not referred for mri, and the error of this model is about 5%. conclusion: here, we proposed a 2-step model for approaching suspected ais patients in ed for an attempt to safely exclude patients with the least probability of having an ais as a diagnosis. however, further surveys are required to assess its accuracy and it may even need some modifications.