PROJECT SUMMARY Diagnostic errors are a significant public health concern and the leading cause of harm due to medical care in the U.S. Estimates suggest that one of every twenty patients seeking healthcare in the U.S. experiences a diagnostic error, half of which result in serious harm. There are many reasons for diagnostic failures. Failures in the process of diagnosis are multifocal, and may relate to patient, clinician, or systems breakdowns and lead to potential patient harm. While there have been modest improvements in reducing diagnostic error, much of this research has focused on defining the scope of the problem and developing tools for doctors to prevent errors, largely ignoring the critical role of the patient in finding and fixing errors in their own healthcare. Our teams prior work shows that patients and their families provide valuable information often missing in medical records that can inform safety problems across different care settings; this includes diagnostic safety events. Furthermore, making accurate and timely diagnoses requires a patient-centered, team-based approach involving collaboration among multiple healthcare professionals, with the patient and their family at its core and recognition of the importance of input from patients across the spectrum of patient populations. The Patient-Partnered Diagnostic Center of Excellence (the Center) will fill these gaps by conducting research that has been identified and prioritized by patients as important to advance diagnostic safety research. The Center is governed by experienced patient-partnered scientists and directed by a committee of patients and an advisory panel of experts who collectively will develop expertise in Safety I error detection and prevention to decrease diagnosis error frequency and Safety II methods of resilience to improve safer care. The Center takes the novel approach of examining diagnostic safety using a Safety I and II lens from the patient's experience of the diagnostic journey. We are committed to meaningfully partnering with minority and equity seeking communities to drive meaningful solutions with broad application for reaching historically marginalized patients. Our Center convenes around three aims, organized into four workstreams led by a co-PI/co-I with demonstrated expertise in that workstream. Our workstreams will work together to inform solution development, cocreating improvements in detection and driving diagnostic safety system resilience in partnership with diverse patients. Our Center benefits from strong scientific expertise in diverse, relevant disciplines; diverse organizational and cultural research sites partnered with care delivery systems; but most importantly meaningful engages patients and community partners in codesign of solutions to prevent diagnostic errors. The Center's findings will inform other Diagnostic Centers of Excellence and patient-centered outcomes research. Our aggressive attention to the inclusion of equity seeking populations in codesign and evaluation will yield diagnostic safety solutions that will be adopted broadly by diverse care settings, patients, and the clinicians that serve them.

PROJECT NARRATIVE Diagnostic errors are a significant public health concern and the leading cause of harm due to medical care in the U.S.; yet research to date has principally focused on the clinician as the center of both the problems and the solutions. The Patient-Partnered Diagnostic Center of Excellence will shift this paradigm by convening diverse scientists and patients around research questions developed and prioritized by patients yielding patient- centered diagnostic safety solutions and reductions in diagnostic safety events. By providing clear evidence by measuring the problem (Safety I) and devising solutions to build diagnostic team resilience (Safety II), our Center has high potential to improve diagnostic safety for all patients in the U.S.