Gender difference in QTc prolongation of people with mental disorders

QTc and psychopharmacs: are there any differences between monotherapy and polytherapy

BACKGROUND

Some psychotropic drugs are connected with prolongation of QT interval, increased risk of cardiac arrhythmias and greater incidence of sudden death, especially when used in combination. Concomitant use of antipsychotics and antidepressants is not rare in our clinical practice. The study compares the length of QT interval in patients on monotherapy with an antipsychotic or an antidepressant and patients taking polytherapy (an antipsychotic agent combined with an antidepressant).

METHODS

Sixty-one hospitalized women who met the ICD-10 criteria for schizophrenia, schizoaffective psychosis, delusional disorder and mood disorder were included in the study. The monotherapy group was consisted of thirty-two women treated with an antipsychotic or an antidepressant while the polytherapy group was composed of twenty-nine women treated with an antipsychotic agent plus an antidepressant. Two electrocardiograms (ECGs) were obtained for each patient: the first was carried out before the treatment and the second after two weeks of treatment.Statistical analysis was carried out by SPSS program and included unpaired and paired t test and Fisher's exact test.

RESULTS

Mean baseline QTc values did not differ between the groups (439 +/- 22 ms was the same value found in the both groups; unpaired t test, p > 0.5). Mean QTc intervals after two weeks of treatment were also similar (439 +/- 24 ms in the monotherapy group and 440 +/- 20 ms in the polytherapy group; unpaired t test, p > 0.5). Fisher's exact test did not reveal significant difference in the number of patients with borderline (451-470 ms) or prolonged (> 470 ms) QTc between groups, neither before treatment nor after two weeks of treatment. Twenty two women of the total of sixty one patients (36%) had QTc > 450 ms before applying therapy.

CONCLUSION

We did not find significant QT prolongation in our patients after two weeks of treatment with antipsychotics and/or antidepressants. The QTc interval length did not differ significantly in the monotherapy and the polytherapy group. More than one third of included women exceeded the threshold value of borderline QTc interval (450 ms) before starting treatment. This finding calls for caution when prescribing drugs to female psychiatric patients, especially if they have other health problems.

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.