Diagnosis of multiple sclerosis: comparison of the Poser criteria and the new McDonald criteria.

OBJECTIVES: A confident and accurate diagnosis of multiple sclerosis (MS) is important, but a specific diagnostic test for the disease does not exist. The traditional diagnostic criteria of Poser et al. were published in 1983, and recently, McDonald et al. recommended new criteria for the diagnosis of MS.

PATIENTS AND METHODS: In this study these two diagnostic schemes were compared by prospectively applying both of them to 76 patients with clinical features suggesting a new diagnosis of MS.

RESULTS: Using the Poser criteria, 29 patients (38%) were classified as clinically definite and 35 patients (46%) as laboratory definite MS. According to the new McDonald criteria, MS was diagnosed in 39 (52%) patients, 37 patients (48%) had 'possible MS'. All patients with a clinically definite MS with the Poser criteria were also given the diagnosis of MS as recommended by McDonald et al. Of those 35 patients with laboratory definite MS according to Poser et al., four patients could be classified as having MS with the McDonald criteria, 89% of them had 'possible MS'. Conversely, 75% of the 39 patients, who fulfilled the new McDonald criteria for MS were assigned to the category of clinically definite MS according to the Poser criteria, and 83% of the patients with a 'possible MS' using the McDonald criteria, had a laboratory definite MS with the Poser criteria.

CONCLUSION: MS according to the McDonald criteria was diagnosed more often than 'clinically definite MS' according to Poser et al., but combining the categories of clinically and laboratory definite MS, the diagnosis of MS could clearly be established more frequently using the Poser criteria.