Antipsychotic drug administration does not correlate with prolonged rate-corrected QT interval in children and adolescents: results from a nested case-control study.

BACKGROUND

The rate-corrected QT interval (QTc) prolongation is a risk factor for sudden cardiac death and may be induced by antipsychotic drugs.

OBJECTIVE

To determine the clinical characteristics associated with QTc prolongation (440 msec or greater) in children and adolescents hospitalized for treatment of psychiatric disorders.

METHOD

We determined the frequency of baseline prolongation of QTc in 811 psychiatric pediatric inpatients (15.5 ± 2.4 years of age). QTc duration was 440 msec or greater (range 441-481 msec) in 16 patients (1.97%). In a 1:5 nested case-control design, the 16 patients with prolonged QTc were age- and gender-matched with 80 patients with QTc of <421 msec.

RESULTS

Patients with normal and prolonged QTc had similar utilization of antipsychotics (43.8% vs. 40.8%) and daily chlorpromazine equivalents (165 ± 110 vs. 168 ± 218 mg). Hypokalemia (p = 0.009) and obesity (p = 0.032) were more common among patients with prolonged QTc. The correlation between obesity and QTc prolongation was confirmed in logistic regression analysis.

CONCLUSIONS

In a large cohort of youth hospitalized for treatment of psychiatric disorders, a prolonged QTc on admission was rare and correlated with the presence of obesity, but not with current use of antipsychotic drugs.