Study Design

We performed a secondary analysis of the GWTG‐R registry, which is a prospective, hospital‐based, clinical registry of patients with in‐hospital cardiac arrest in the United States. The design and maintenance of the registry has been described in detail previously.15 Briefly, the registry consists of patients with cardiac arrest, identified as loss of palpable central pulse, apnea, and impaired consciousness. Patients who have received cardiopulmonary resuscitation and meet the definition of cardiac arrest, as defined by Utstein criteria,16 are included. Specially trained personnel at each institution are charged with data abstraction from the medical record and inclusion in the GWTG‐R database. To ensure that all cases are captured, multiple sources of case identification are explored, including hospital code logs, centralized collection of cardiac arrest flow sheets, inventory of code carts, and review of hospital‐based billing for code drugs.15 The registry is based on standardized Utstein definitions for clinical variables and outcomes.16

This study was approved by the Colorado Multiple Institutional Review Board with a waiver of the requirement for informed consent, as the study used deidentified data.