Retrospective comparison of the original and revised McDonald criteria in a general neurology practice in Ireland

Background The McDonald criteria were introduced in 2001 as guidelines to facilitate early and accurate diagnosis of multiple sclerosis ( MS). They were revised in 2005. Although validated in a number of research-focused clinical centres, their adequacy and utility in the general neurology setting is less certain. Objective In this study, we assessed new diagnoses of MS in our practice for compliance with both the original and the revised criteria. Methods We retrospectively identified new diagnoses of MS from 2001. Clinical notes and imaging were evaluated for compliance with McDonald criteria. Results Sixty-two patients were included: 53 with 'practice-definite' and nine with 'practice-possible' diagnoses of MS. At the time of diagnosis, 47% of the 'practice-definite' group fulfilled the 2001 criteria and 49% the revised criteria. Among patients not satisfying the criteria at time of diagnosis, 21% went on to fulfil the McDonald criteria over the 23-month follow-up. Conclusions There is a considerable gap between the clinical diagnosis of MS in a general neurology setting and compliance with the McDonald criteria. Failure to perform follow-up MRI on patients with clinically isolated syndromes is a sizeable factor in this diagnostic-gap and needs to be improved. In this setting, practical differences between the original and revised criteria appear to be small.