We made a strategic decision to focus on achieving our targeted cohort size of >30,000 GPC participants. We chose to concentrate our case ascertainment and participant enrollment on individuals with clear clinical diagnoses. Potential cases were drawn from patients whose diagnosis of schizophrenia, schizoaffective disorder, or bipolar disorder had been consistent from their treating psychiatrist and in their medical records. Using these initial screening procedures, less than one percent of individuals initially recruited as potential cases failed to meet criteria for one of the diagnoses under study after DI-PAD interview and OPRIT/best estimate diagnoses. A great deal of effort in many prior studies was focused on the least clear cases; such cases often remained unclear even after extremely thorough best estimate processes.
