Misdiagnosis of Posterior Reversible Encephalopathy Syndrome and Reversible Cerebral Vasoconstriction Syndrome in the Emergency Department.

Background Cerebrovascular dysregulation syndromes, posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS), are challenging to diagnose because they are rare and require advanced neuroimaging for confirmation. We sought to estimate PRES/RCVS misdiagnosis in the emergency department and its associated factors. Methods and Results We conducted a retrospective cohort study of PRES/RCVS patients using administrative claims data from 11 states (2016-2018). We defined patients with a probable PRES/RCVS misdiagnosis as those with an emergency department visit for a neurological symptom resulting in discharge to home that occurred ≤14 days before PRES/RCVS hospitalization. Proportions of patients with probable misdiagnosis were calculated, characteristics of patients with and without probable misdiagnosis were compared, and regression analyses adjusted for demographics and comorbidities were performed to identify factors affecting probable misdiagnosis. We identified 4633 patients with PRES/RCVS. A total of 210 patients (4.53% [95% CI, 3.97-5.17]) had a probable preceding emergency department misdiagnosis; these patients were younger (mean age, 48 versus 54 years;