Stroke Prognostic Instrument II (SPI-II) Calculator

Stroke Prognostic Instrument II (SPI-II): Explanation and Clinical Context The Stroke Prognostic Instrument II (SPI-II) is a validated clinical scoring system designed to predict the risk of recurrent stroke or major vascular events (such as myocardial infarction or vascular death) in patients with a prior non-cardioembolic ischemic stroke. SPI-II was developed from the National Institute of Neurological Disorders and Stroke (NINDS) Stroke Data Bank as an update to the original SPI-I, improving accuracy by refining clinical predictors. It assigns weighted points to seven easily obtainable variables: age >70 years (2 points), and six additional factors (1 point each)—hypertension, diabetes mellitus, heart disease (coronary artery disease, heart failure, or atrial fibrillation), prior stroke, moderate-to-severe neurological deficit, and current smoking.

The total score (range 0–8) stratifies patients into three categories: low (0–3), moderate (4–6), and high risk (7–8). These correspond to approximately 6%, 14%, and 29% 2-year risks for recurrent vascular events, respectively. Clinically, SPI-II assists physicians in secondary prevention planning after ischemic stroke, guiding the intensity of risk factor management, antiplatelet therapy selection, and follow-up strategy.

The model emphasizes traditional vascular risk factors and clinical severity rather than imaging or laboratory data, making it simple and practical for bedside or outpatient use.