MISDIAGNOSIS IN MULTIPLE SCLEROSIS IN A BRAZILIAN REFERENCE CENTER: CLINICAL, RADIOLOGICAL, LABORATORY PROFILE AND FAILURES IN THE DIAGNOSTIC PROCESS – COHORT STUDY

Introduction: Misdiagnosis in multiple sclerosis remains a problem despite the well validated McDonald 2017 criteria. Recent studies reported patients previously diagnosed with multiple sclerosis, and after being referred to specialized centers they had their diagnosis changed to other conditions. However, reports that evaluate misdiagnosis in multiple sclerosis, including patients who were already on regular follow up at reference centers of demyelinating diseases with the diagnosis of multiple sclerosis, are scarce. Objectives: We aimed to evaluate multiple sclerosis misdiagnosis in patients that are on follow up at a reference center of demyelinating diseases in Brazil. Methods: We designed an observational study including patients who were diagnosed with multiple sclerosis at our specialized outpatient clinic in Sao Paulo, from 1996 to 2021 and were reassessed for misdiagnosis in 2022. We evaluated demographic information, clinical profile, complementary exams and the use of disease modifying therapy, and classified participants as “established multiple sclerosis”, “suspected multiple sclerosis” and “non- multiple sclerosis”. We reported the alternative diagnoses of our participants, and we calculated the misdiagnosis rate in our center. Failures in the diagnostic process were assessed by the modified Diagnostic Error Evaluation and Research tool. Results: 201 patients were included, and after analysis, 191/201 (95,02%) participants were confirmed as “established multiple sclerosis”, 5/201 (2,49%) were defined as “suspected multiple sclerosis” and 5/201 (2,49%) were defined as “non-multiple sclerosis”. The main failures in the diagnostic process were due to the misinterpretation of the magnetic resonance imaging. We confirmed a case of misdiagnosis due to Human T-lymphotropic virus type 1 infection, a disease that is more commonly found in South America, compared to the rest of the world. Conclusions: Multiple sclerosis misdiagnosis remains a problem even in reference centers of demyelinating diseases and caution should be taken in making the correct diagnosis.