Compliance with McDonald criteria and red flag recognition in a general neurology practice in Ireland

Background: The revised McDonald criteria aim to simplify and speed the diagnosis of multiple sclerosis (MS). An important principle of the criteria holds there should be no better explanation for the clinical presentation. In Miller et al.'s consensus statement on the differential diagnosis of MS, red flags are identified that may suggest a non-MS diagnosis. Objective: All new patients with a practice diagnosis of MS were assessed for compliance with McDonald criteria. The group of patients not fulfilling criteria was followed up to assess compliance over time. At the end of the follow-up period, red flags were sought in the group of patients who remained McDonald criteria negative. Methods: Clinical notes and paraclinical tests were examined retrospectively for compliance with McDonald criteria and for the presence of red flags. Results: Sixty-two patients were identified, with two lost to follow-up. Twenty-six (42%) patients fulfilled criteria at diagnosis. After 53 months follow-up, 47 (78%) patients fulfilled criteria. In the 13 (22%) patients who remain McDonald criteria negative, a total of 20 red flags were identified, ranging from one to six per patient. Alternative diagnoses were considered and further investigations performed in 10 patients with no significantly abnormal results. Conclusion: Twenty-two percent of patients still do not fulfill McDonald criteria after 53 months. Dissemination in time was not proven in the majority of patients and the lack of follow-up neuroimaging was an important factor in this. Red flags may be useful in identifying alternative diagnoses, but the yield was low in our cohort.