Automated Risk Stratification for Corrected QT Interval (QTc) Prolongation Related to Haloperidol Use

Objectives: Automated clinical risk scores have been developed to identify patients at high risk of medication-induced corrected QT interval (QTc) prolongation and torsades de pointes (TdP).This study aimed to describe the incidence and magnitude of QTc prolongation following haloperidol administration among hospitalized patients identified as high risk for TdP by an automated, modified Tisdale risk score.A secondary objective was to identify clinical and medication-related factors associated with marked QTc prolongation in this high-risk population.Methods: This was a cross-sectional observational study approved by the Institutional Review Board.We included 36 patients aged >18 years admitted to one of 15 hospitals in Arizona or neighboring states between January 2020 and February 2026.Patients received at least one dose of haloperidol during their stay.Outcomes investigated were a relative QTc prolongation of ≥20 ms above baseline, or an absolute QTc ≥500 ms, as defined using Fridericia's formula.Patient demographic information, laboratory values, and medication exposures were obtained from the chart to determine risk factors for QTc prolongation.Results: Eighteen (50%) patients given haloperidol had a relative QTc increase of ≥20 ms, and nine (25%) had an absolute QTc of ≥500 ms.Concurrent diuretic use was significantly associated (p = 0.014) with absolute QTc prolongation of ≥500 ms.Conclusions: There is a significant incidence of both relative and absolute QTc prolongation in patients identified as high risk by an automated clinical risk score who were prescribed haloperidol.These findings support further investigation of automated risk stratification as a means of identifying patients who may warrant targeted QTc monitoring and medication review.Caution may be advised with the concurrent use of haloperidol and diuretics in identified high-risk patients.