The critical role of pharmacovigilance in monitoring drug-induced QT prolongation

Sir,

In the recent cross-sectional study¹ on QT interval prolongation in schizophrenia published in the June issue of the Indian Journal of Medical Research, the authors have done a remarkable job in highlighting the prevalence of QTc prolongation in patients with schizophrenia, a serious cardiac adverse effect of antipsychotic medications.¹ Their findings, which report QTc prolongation 3.4% of participants using Fridericia’s formula and 6.8% using Bazett’s formula, are significant as they underscore a potentially fatal cardiac risk, Torsades de Pointes (TdP).

The study emphasises the need for regular screening and periodic assessment of cardiac rhythm in these patients. However, it needs to be stressed that such findings are not just for clinical awareness; they are crucial for a robust pharmacovigilance system. Every single adverse drug reaction (ADR), including QTc prolongation, identified at a hospital or tertiary care centre must be reported to the Pharmacovigilance Programme of India (PvPI). This can be done through the designated ADR Monitoring Centre (ADRMC) or by self-reporting via any of the available online or social media portals.² In this study, the authors have not clarified whether they had reported these adverse reactions to the respective ADR monitoring centre.

The data gathered from such systematic reporting is essential for enhancing patient safety. This allows for the collective analysis of real-world drug safety data, which in turn helps to identify emerging risk factors and evaluate the safety profile of drugs in diverse populations, and inform regulatory authorities.³ For example, this study noted that olanzapine was the most frequently prescribed antipsychotic and was linked to all three cases of QTc prolongation identified by Fridericia’s formula. This kind of observation, when aggregated through nationwide reporting, can help confirm and quantify such risks on a larger scale.

Numerous studies from India have demonstrated poor knowledge, attitude, and practice of pharmacovigilance among medical professionals, which can be countered through robust sensitization measures undertaken by the ADR monitoring centres.^4,5 Hence, all studies undertaken in academic institutions should also report their adverse effects to the respective ADR monitoring centres.

The author’s conclusion that medical practitioners should be aware of these adverse effects and take necessary precautions is vital. This awareness extends to their responsibility to report any and all adverse events, thereby contributing to a larger database that protects not just a few patients but the entire population. The development of QTc prolongation leading to Torse de Pointes (TdP) is a serious cardiac event. Timely interventions, such as screening for comorbidities, avoiding polypharmacy, and switching medications, are of utmost importance. Yet, none of these interventions are as powerful as a well-informed and comprehensive pharmacovigilance system fuelled by diligent reporting from the medical community.