Development and validation of a SCORing systEm for pre-thrombectomy diagnosis of IntraCranial Atherosclerotic Disease (Score-ICAD)

Background Early identification of intracranial atherosclerotic disease (ICAD) may impact the management of patients undergoing mechanical thrombectomy (MT). We sought to develop and validate a scoring system for pre-thrombectomy diagnosis of ICAD in anterior circulation large vessel/distal medium vessel occlusion strokes (LVOs/DMVOs). Methods Retrospective analysis of two prospectively maintained comprehensive stroke center databases including patients with anterior circulation occlusions spanning 2010–22 (development cohort) and 2018–22 (validation cohort). ICAD cases were matched for age and sex (1:1) to non-ICAD controls. Results Of 2870 MTs within the study period, 348 patients were included in the development cohort: 174 anterior circulation ICAD (6% of 2870 MTs) and 174 controls. Multivariable analysis β coefficients led to a 20 point scale: absence of atrial fibrillation (5); vascular risk factor burden (1) for each of hypertension, diabetes, smoking, and hyperlipidemia; multifocal single artery stenoses on CT angiography (3); absence of territorial cortical infarct (3); presence of borderzone infarct (3); or ipsilateral carotid siphon calcification (2). The validation cohort comprised 56 ICAD patients (4.1% of 1359 MTs): 56 controls. Area under the receiver operating characteristic curve was 0.88 (0.84–0.91) and 0.82 (0.73–0.89) in the development and validation cohorts, respectively. Calibration slope and intercept showed a good fit for the development cohort although with overestimated risk for the validation cohort. After intercept adjustment, the overestimation was corrected (intercept 0, 95% CI −0.5 to –0.5; slope 0.8, 95% CI 0.5 to 1.1). In the full cohort (n=414), ≥11 points showed the best performance for distinguishing ICAD from non-ICAD, with 0.71 (95% CI 0.65 to 0.78) sensitivity and 0.82 (95% CI 0.77 to 0.87) specificity, and 3.92 (95% CI 2.92 to 5.28) positive and 0.35 (95% CI 0.28 to 0.44) negative likelihood ratio. Scores ≥12 showed 90% specificity and 63% sensitivity. Conclusion The proposed scoring system for preprocedural diagnosis of ICAD LVOs and DMVOs presented satisfactory discrimination and calibration based on clinical and non-invasive radiological data.