Electrocardiographic monitoring for QT prolongation in patients treated with ziprasidone--a claims database approach.

Purpose: Drug-induced cardiac arrhythmia is a major safety concern for drugs with a potential to prolong the QT interval. The purpose of the study is to examine whether timely electrocardiographic (ECG) monitoring has been performed for patients treated with ziprasidone.

Methods: Out-patient pharmacy claims data abstracted from Taiwan's National Health Insurance Research Database were used to identify patients treated with ziprasidone. Based on the dataset sorted by the encrypted patient identifier and by date, the rates of ECG performed before and during treatment were examined. The intervals between treatment beginning and ECG examination during therapy were calculated.

Results: Among 4789 patients ever treated with zipasidone, 229 (4.8%) had ECG performed before treatment. Among 2052 patients treated with a longer duration of ziprasidone, 394 (19.2%) had ECG performed during treatment. They included 64 (3.1%) patients who had it performed within the first 30 days of treatment, 124 (6.0%) within 60 days and 178 (8.7%) within 90 days. The mean interval was 157.4 days (95% confidence interval (CI), 143.0-171.8) between treatment beginning and the first on-therapy ECG examination and was 210.4 days (95%CI, 178.6-242.2) between treatment beginning and the second ECG.

Conclusions: Low rates of ECG examination before and during therapy were noted among patients treated with ziprasidone. It took significant length of time to perform ECG monitoring after treatment was started. Although the patients studied had few risk factors for cardiac arrhythmia, ECG monitoring for patients using ziprasdione could be improved.