Supplementary Material for: Stratifying the Utility of Transthoracic Echocardiography for Ischemic Stroke using a Risk Score

Introduction: Inpatient transthoracic echocardiography (TTE) is considered to be an important part of secondary prevention in acute ischemic stroke, but can be a barrier to discharge. The goal of the study is to generate a risk score to assess which patients will benefit from a TTE in the inpatient setting.

Methods: The training data set consisted of all 874 patients from the UW Health Comprehensive Stroke Registry admitted for acute ischemic stroke / TIA from 2017 and 2018 that received a TTE. A validation data set of 200 stroke patients was used from the Indiana University Stroke Registry. Using the training data, a modified logistic regression model was developed with simplified coefficients and a limited number of variables. The area under the receiver operator characteristic curve (AUC) was compared between deferent models and between the training and validation data sets.

Results: The training data consisted of 874 patients (52.9% male; median age 64 years). Validation data set consisted of 200 patients (53.5% male; median age, 64 years). For the final model, termed AL2OHA, mean AUC on the training data across five-fold cross validation was 0.78 (95% CI, 0.76 - 0.80). The model consisted of six variables, and one point was awarded for each: atrial fibrillation, large artery atherosclerosis, large vessel occlusion, obesity, prior anti-hypertensive medication usage and if patient’s age was 18-39 or ≥ 70. Risk of positive findings was 6.2% for score of 0, 23.1% for score of 1, 57.4% for score of 2, 85.8% for score of 3, 96.4% for score of 4, and 99.2% for score of 5 or greater. When tested on the external validation data set, AUC was 0.73 and demonstrated to not be significantly different than the AUC for the training data set.

Conclusions: The AL2OHA model is a clinical tool which can stratify which patients admitted for acute ischemic stroke/TIA are more likely to benefit from inpatient TTE’s.