Real-world challenges in the diagnosis of primary progressive multiple sclerosis.

Abstract

Despite the 2017 revisions to the McDonald criteria, diagnosing primary progressive multiple sclerosis (PPMS) remains challenging. To improve clinical practice, we aimed to identify frequent diagnostic challenges in a real-world setting and associate these with the performance of the 2010 and 2017 PPMS diagnostic McDonald criteria. We retrospectively recorded clinical, radiological and laboratory characteristics at time of diagnosis from designated PPMS patient files. Possible complicating factors were recorded such as confounding comorbidity, signs indicative of alternative diagnoses, possible earlier relapses, and/or incomplete diagnostic workup (no cerebrospinal fluid examination and/or MRI brain and spinal cord). We calculated the percentages of patients fulfilling the 2010 and 2017 McDonald criteria after censoring patients with these complicating factors. A total of 322 designated PPMS patients were included. Of all participants, we found that n=28/322 had confounding comorbidity and/or signs indicative of alternative diagnoses, n=103/294 had possible initial relapsing and/or uncertainly progressive phenotypes, and n=73/191 received an incomplete diagnostic work-up. When applying the 2010 and 2017 diagnostic PPMS McDonald criteria on n=118 cases with a full diagnostic workup and a primary progressive disease course without a better alternative explanation, these were met by 104/118 (88.1%) and 98/118 remaining patients (83.1%), respectively (p=0.15). Accurate interpretation of the initial clinical course, consideration of alternative diagnoses, and a full diagnostic workup are the cornerstones of a PPMS diagnosis. When these conditions are met, the 2010 and 2017 McDonald criteria for PPMS perform similarly, emphasizing the importance of their appropriate application in clinical practice.