Predictive factors for QTc prolongation in schizophrenic patients taking antipsychotics

The rate-corrected electrocardiographic QT (QTc) interval may significantly increase in schizophrenic patients taking antipsychotics. QTc prolongation is a risk factor for development of arrhythmia. The objective of this study was to assess the predictors of QTc prolongation in schizophrenic patients taking antipsychotic medication.

Electrocardiograms were obtained from 138 controls and 412 schizophrenic inpatients taking antipsychotics. QTc prolongation was defined as a mean value of 2 standard deviations above the controls. Predictors were analyzed with a logistic regression model.

Based on data obtained from controls, QTc prolongation was defined as a QTc greater than 421 ms. Logistic regression analysis showed that significant predictors for QTc prolongation were: female gender (odds ratio, 3.355 [95% CI, 1.767-6.371]); increased age (1.040 [1.011-1.069]); and increased doses of some antipsychotics, including clozapine (1.006 [1.003-1.008]), chlorpromazine (1.003 [1.002-1.005]), thioridazine (1.007 [1.003-1.011]), and sulpiride (1.001 [1.001-1.002]).

Predictors of the QTc prolongation in schizophrenic patients taking antipsychotic medications were female gender, old age, and treatment with clozapine, chlorpromazine, thiroridazine, or sulpiride.