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

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.