Prevalence and Risk Factors of Drug-Associated Corrected QT Prolongation in Elderly Hospitalized Patients: Results of a Retrospective Analysis of Data Obtained Over 6 Months.

Objectives: Little information exists on the frequency and determinants of drug-associated long QT syndrome in older adults. The objectives of this study were to assess the prevalence and identify risk factors of drug-associated long QT syndrome in a population of elderly hospitalized patients.

Methods: This was a retrospective study performed over 6 months in hospital geriatric medicine. Various QT-correction equations were fitted to the individual QT-RR data to evaluate the most appropriate equation. Long QT syndrome was defined as corrected QT ≥450 ms. Available data were compared in patients with and without long QT syndrome. Logistic regression and classification and regression tree analysis were performed to identify determinants of long QT syndrome.

Results: Thirty-three of 152 patients (22%) exhibited corrected QT ≥450 ms. The different QT correction equations provided similar results, except the Bazett equation. In patients with long QT syndrome, there was a higher proportion of male subjects (58 vs. 33%, p = 0.009) and a higher number of QT-prolonging drugs than in patients without long QT syndrome. Male sex (odds ratio, 3.25) and the number of prescribed QT-prolonging agents (odds ratio, 1.77) were significantly associated with the probability of long QT syndrome. The number of QT-prolonging drugs had a stronger influence on the risk of long QT syndrome in men than in women.

Conclusion: Male sex was found to be a significant risk factor of corrected QT prolongation in elderly hospitalized patients. The risk also increased with the number of QT-prolonging agents, especially in men. Those findings may help to mitigate the risk of long QT syndrome in elderly patients in clinical practice.