Patient-based scenario-driven usability tests are routinely created for health information technology and clinical decision support evaluations. Due to low clinician awareness of sepsis, a study was undertaken to understand clinician performance and preference of different display types for sepsis clinical decision support through multi-centered usability testing. Patient-based clinical scenarios were created to mimic the environment in which providers would interact with clinical decision support. The data provided in the scenarios were drawn from real patient cases from two sepsis databases, including: demographics, visit/operational details, medical history (comorbidities, assessments, vital signs, laboratory values, clinician documentation), and patient disposition/outcomes. The purpose of this work is to inform electronic health record alert optimization and clinical practice workflow to support the effective and timely delivery of high quality sepsis care. This paper discusses the methodology, selection, and validation of patient-based cases used as the clinical scenarios in usability testing.