The Ziprasidone Observational Study of Cardiac Outcomes (ZODIAC): Design and Baseline Subject Characteristics

Background: Ziprasidone has been used to treat schizophrenia since 2000. It is unknown whether its modest QTc-prolonging effect increases cardiovascular event risk.

Purpose: To describe the study design of the Ziprasidone Observational Study of Cardiac Outcomes (ZODIAC).

Method: The study was conducted between February 2002 and February 2006. One-year follow-up for the primary endpoint of nonsuicide death ended in April 2007. ZODIAC is an open-label, randomized, postmarketing study enrolling patients with schizophrenia in naturalistic practice in 18 countries. The primary outcome measure was the rate of nonsuicide mortality in the year after initial recommendation for therapy. Subjects were randomly assigned to either ziprasidone or olanzapine, after which follow-up was conducted by investigators aware of the assigned exposure. A physician-administered questionnaire collected baseline information on patients’ demographics, medical and psychiatric history, and concomitant medication use. Data were self-reported by patients or reported by enrolling physicians.

Results: ZODIAC enrolled 18,240 patients with schizophrenia. Most (73.0%) were from the United States or Brazil. Patients’ baseline mean age was 41.6 years, 55.1% were male, and 60.0% were white. At baseline, approximately 18% had hypertension, 14.8% had hyperlipidemia, 46.5% currently smoked, 28.9% had a body mass index >= 30 kg/m², and 7.7% had diabetes. Mean time from schizophrenia diagnosis to study enrollment was 10.4 years and mean Clinical Global Impressions scale score was 5.2 (range: 1-8). Nearly one third of patients had ever attempted suicide. Seventy-one percent were using antipsychotics at baseline. Almost 80% were using concomitant medications, with 29.5% using antidepressants, 25.4% using anxiolytics, and 19.0% using mood stabilizers. Less than 3% were using antihypertensives or statins.

Conclusions: ZODIAC is a uniquely designed study with an initial randomization to ziprasidone or olanzapine and follow-up largely consistent with usual practice (i.e., many characteristics of a nonexperimental study). Baseline data suggest this study population has a substantial prevalence of cardiovascular risk factors. Concomitant medications were used frequently, although hyperlipidemia and hypertension may be undertreated.