Validation of a Clinical Decision Support Tool for Quantifying Risk of Torsades de Pointes in a Psychiatric Inpatient Population

Abstract

Objective: Psychiatric inpatients often require complex medication regimens due to the refractory nature of their serious mental illness (SMI) and the high prevalence of medical comorbidities. Among the many inherent issues associated with these regimens are the potential pharmacodynamic drug interactions resulting in an increased risk of QTc prolongation and the potential sequelae, Torsades de Pointes (TdP). This study builds on previous research that demonstrated the utility of the MedSafety Scan (MSS) clinical decision support (CDS) tool by establishing theoretical evidence from patients with SMI but did not provide objective data to validate its use in this population. This has left prescribers questioning whether the MSS CDS tool is capable of accurately guiding prescribing decisions in this vulnerable patient population. Therefore, the objective of this study was to assess the degree of correlation between psychiatric patients' QTc intervals and their MSS-calculated TdP risk scores to objectively validate the predictive impact and clinical value of the MSS tool in psychiatric inpatients for the purpose of informing safe prescribing.

Methods: A retrospective analysis was conducted to assess the relationship between participants' MSS TdP risk scores and their QTc Δ, defined as the difference between participants' measured QTc intervals and sex-specific QTc prolongation thresholds (female individuals: 470ms; male individuals: 450ms). The MSS TdP risk score is calculated based on patient demographic data, medical diagnoses, serum electrolyte values, and medications. Data from 251 subjects were extracted from an adult inpatient psychiatric facility's electronic medical record system from February 1, 2018, through November 30, 2023. Inpatients with a documented electrocardiogram during the study period were eligible for inclusion, and the exclusion criterion was having a Criminal Procedure Law (CPL) designation. Data were analyzed using a one-way analysis of variance (ANOVA) with alpha set to 0.01.

Results: The data from the ANOVA that compared participants' QTc Δ to MSS TdP risk score were found to be significant (p<0.01).

Conclusion: This study showed that the MSS CDS tool accurately reflected the relationship between our psychiatric inpatients' measured QTc intervals and their predicted MSS TdP risk scores, which objectively validated the predictive impact and clinical utility of this tool in our psychiatric population. Prescribers can use this tool to mitigate QTc prolongation risk for patients without underlying, unknown congenital risk; therefore, this can be an important course of action in treating psychiatric patients, given their predisposition to decreased lifespans and their increased risk of QTc prolongation due to SMI-related proarrhythmic factors. The MSS tool is an open-source, web-based CDS tool that provides comprehensive analyses of TdP risk, drug interactions, and duplicate therapies, and produces a detailed patient-specific report that allows for documentation of management plans. These features prove MSS to be a valuable tool for psychiatric inpatient clinicians to establish an initial basic clinical impression to advise need for additional comprehensive medical follow-up, cardiology consultation, or pharmacotherapeutic modifications.

Keywords: MedSafety Scan; QTc interval; QTc prolongation; Torsades de Pointes; antidepressants; antipsychotics; clinical decision support tool.