The reliability of specific primary progressive MS criteria in an ethnically diverse population

Three different diagnostic criteria for primary progressive MS were recently proposed for Caucasian population of Western European region. Objective: The objective of the study was to apply these criteria to a series of Brazilian patients with high ethnic diversity background to evaluate reproducibility and reliability. Methods: 52 patients classified as form of the disease that is progressive from onset and followed between 2000 and 2006 were included. Thompson, McDonald and Polman criteria were applied based in clinical date and complementary exams. Results: 72% fulfilled all three criteria with moderate agreement (p < 0.001). Ten patients fulfilled at least one criterion and four failed to fulfill any of the three criteria. Strong agreement was found between Thompson and McDonald criteria (p < 0.001), agreement was moderate between Thompson and Polman criteria (p < 0.001) and weak agreement occurred between McDonald and Polman criteria (p = 0.042). Conclusion: The main difference between these criteria is the change in the role of CSF, previously a prerequisite for diagnosis. Rigid diagnostic criteria as Thompson have higher specificity, should be used in clinical research protocols, while more flexible criteria as Polman facilitate the diagnosis of PPMS in neurological practice, particularly in initial stages of the disease, because of their potentially higher sensitivity.