Corrected QT intervals in newly admitted geriatric psychiatric patients: an examination of risk factors.

OBJECTIVES

The primary objective of this study was to determine the incidence of prolonged corrected QT (QTc) intervals in a population of geriatric psychiatry inpatients. Our secondary objective was to examine the associations between prolonged QTc intervals and risk factors identified as determinants in prolonging the QTc interval.

METHODS

We identified all geriatric patients (aged 60 years and older) who were admitted to the geriatric program of our facility between May 1, 2003, and December 31, 2003. Those patients with a heart rate QTc interval calculated on the electrocardiogram (ECG) were eligible for the study. We used Bazett's formula to calculate the QTc interval. We defined a priori that a prolonged QTc interval would be 450 ms and 460 ms for men and women, respectively. We collected data on demographic variables such as weight, sex, age, and Axis I and III diagnoses, as well as on recognized risk factors for prolonged QTc interval. We used Student's t tests to conduct parametric analysis on continuous variables, and chi-square to test categorical variables for independence.

RESULTS

During the study period, 88 patients were admitted to the geriatric division of Riverview Hospital. Of these patients, 34 men and 42 women had calculated QTc intervals on their ECG and therefore made up the study population. Our data show that 29.4% of men and 21.4% of women had prolonged QTc intervals. However, neither diagnostic nor medicinal risk factors were found to be associated with an increased incidence of prolonged QTc interval in this patient population.

CONCLUSION

The preliminary findings of this study suggest that in this patient population the QTc interval may not be influenced by recognized risk factors to the same extent as observed in the adult population. These results warrant confirmation by a larger, prospectively designed study.