Incidence of multiple sclerosis misdiagnosis in referrals to two academic centers

Background: Multiple Sclerosis (MS) specialists routinely evaluate misdiagnosed patients, or patients incorrectly assigned a diagnosis of MS. Misdiagnosis has significant implications for patient morbidity and healthcare costs, yet its contemporary incidence is unknown. We examined the incidence of MS misdiagnosis in new patients referred to two academic MS referral centers, their most common alternate diagnoses, and factors associated with misdiagnosis. Methods: Demographic data, comorbidities, neurological examination findings, radiographic and laboratory results, a determination of 2010 McDonald Criteria fulfillment, and final diagnoses were collected from all new patient evaluations completed at the Cedars-Sinai Medical Center and the University of California, Los Angeles MS clinics over twelve months. Results: Of the 241 new patients referred with an established diagnosis of MS, 17% at Cedars-Sinai and 19% at UCLA were identified as having been misdiagnosed. The most common alternative diagnoses were migraine (16%), radiologically isolated syndrome (9%), spondylopathy (7%), and neuropathy (7%). Clinical syndromes and radiographic findings atypical for MS were both associated with misdiagnosis. The misdiagnosed group received approximately 110 patient-years of unnecessary MS disease modifying therapy. Conclusion: MS misdiagnosis is common; in our combined cohort, almost 1 in 5 patients who carried an established diagnosis of MS did not fulfill contemporary McDonald Criteria and had a more likely alternate diagnosis.