The START nomogram for individualized prediction of the probability of unfavorable outcome after intravenous thrombolysis for stroke.

Abstract

Background and purpose The nomogram is an important component of modern medical decision-making, which calculates the probability of an event entirely based on individual characteristics. We aimed to develop and validate a nomogram for individualized prediction of the probability of unfavorable outcome in intravenous thrombolysis-treated stroke patients included in the large multicenter Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register. Methods All patients registered in the Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register by 179 Italian centers between May 2001 and March 2016 were originally included. The main outcome measure was three-month unfavorable outcome (modified Rankin Scale 3-6). Four non-categorical predictors of unfavorable outcome (baseline National Institutes of Health (NIH) Stroke Scale score: 0-25, age ≥18 years, pre-stroke modified Rankin Scale score: 0-2, and onset-to-treatment time: 0-270 min) were identified a-priori by three neurologists with expertise in the management of stroke. To generate the NIHSS STroke Scale score, Age, pre-stroke mRS score, onset-to-treatment Time (START), the pre-established predictors were entered into a logistic regression model. The discriminative performance of the model was assessed using the area under the receiver operating characteristic curve. Results A total of 15,862 patients with complete data for generating the START was randomly dichotomized into training (2/3, n = 10,574) and test (1/3, n = 5288) sets. The area under the receiver operating characteristic curve of START was 0.800 (95% confidence interval: 0.792-0.809) in the training set and 0.815 (95% confidence interval: 0.804-0.822) in the test set. Conclusions By using a limited number of non-categorical predictors, the START is the first nomogram developed and validated in a large Safe Implementation of Thrombolysis in Stroke-International Stroke Thrombolysis Register cohort, which reliably calculates the probability of unfavorable outcome in intravenous thrombolysis-treated stroke patients.