Maximizing efficiency and diagnostic accuracy triage of acute stroke patients: A case-control study

Background: Recent data have demonstrated that mechanical thrombectomy (MT) is beneficial for patients presenting within zero to six hours of symptom onset after stroke. However, transferring all patients with possible strokes for endovascular therapy and MT would be inefficient and costly. We conducted a case-control study to identify a subset of the National Institutes of Health Stroke Scale (NIHSS) to identify patients with large-vessel occlusion (LVO) to a high degree of specificity, in order to select those patients for whom transfer is most appropriate.

Methods: Acute code stroke alerts presenting to a comprehensive stroke center from 2012 to 2013 (779) and corresponding NIHSS were collected. All patients had vascular imaging and 125 demonstrated LVO (cases) and were compared to 272 small-vessel strokes and stroke mimics (controls). Demographics of both groups and modified receiver operating characteristic (ROC) curves were generated for each combination of three NIHSS items to optimize specificity of LVO for those who would benefit from MT.

Results: The average NIHSS of cases was higher than controls (12.5 vs. 6.5, p < 0.0001). The subset of three NIHSS items with the largest modified AUC (optimized for specificity) was maximum "Arm," "Sensory," and "Extinction." Using a cutoff of seven out of a total 10 possible points, the sum score for these items has 90.2% specificity and 16.0% sensitivity for LVO.

Conclusion: We present a validated three-question subset of the NIHSS for those who would benefit from MT with a high degree of specificity.