INTRODUCTION
The QT interval is an electrocardiogram (ECG) representation of ventricular depolarization and repolarization.1Torsades de pointes (TdP) is a life-threatening polymorphic ventricular tachycardia associated with QT interval prolongation.1The risk for TdP increases as the heart-corrected QT (QTc) interval increases, specifically when it exceeds 500 milliseconds (ms).2 The American Heart Association and the American College of Cardiology Foundation have published a scientific statement to raise awareness on the risk, ECG monitoring, and management of drug-induced QTc interval prolongation and TdP in hospitalized patients.3 Several risk factors contribute to QTc prolongation including increased age, female gender, QTc-prolonging medications, presence of cardiovascular disease, renal failure and electrolyte abnormalities.4
Clinical Decision Support Systems (CDSS) including alert generation for drug-drug interactions (DDIs) are designed to improve clinical decision making. Since QTc prolongation in hospitalized patients increases the risk of TdP, many institutions employ alerts within their prescribing systems when more than one QTc-prolonging medication is prescribed. However, a primary limitation of CDSS is alert desensitization, or alert fatigue, where alerts are frequently overridden by clinicians due to patient non-specificity or low risk.5
Multiple investigators have developed methods for risk quantification through a QTc risk score. Tisdale et al.6 developed a CDSS incorporating a weighted QTc risk score with 67-74% sensitivity and 77-88% specificity that reduced both risk of QTc prolongation and prescribing of non-cardiac medications known to cause TdP. Similarly, investigators at the Mayo Clinic developed a QTc interval risk score where they found a higher predicted mortality with a score of 4 or greater; however, all risk factors were allocated one point.7 Given the lacking evidence of how risk factors should be weighed, a systematic analysis was conducted by Vandael et al. to generate an evidence-based list of all risk factors associated with QTc prolongation.8 Using the evidence per risk factor, a preliminary risk score for QTc prolongation (RISQ-PATH) was developed in an academic tertiary care medical center in Belgium, and points were allocated in accordance with the evidence level in the systematic review. The risk score was found to have a high sensitivity (96.2%) and negative predictive value (NPV; 98%) with a cutoff of 10 points.9 This score was further optimized and validated in a large patient cohort including 60,208 patients, where the authors reported a sensitivity of ± 87% and a specificity of ± 45%.5