Multiple Sclerosis, 1 October 2003, vol. 9, no. 5, pp. 481-485(5)Zipoli
V.; Portaccio E.; Siracusa G.; Pracucci G.; Sorbi S.; Amato
 Department of Neurology, University of Florence, Florence, Italy
We assessed the interobserver agreement on the diagnosis of multiple sclerosis (MS) in a study sample consisting of 41 MS (15 relapsing–remitting, two secondary progressive, five primary progressive and 19 presenting their first clinical attack) and three non-MS cases.
Clinical and paraclinical information was recorded in standardized forms.
Four neurologists were asked to make a diagnosis using Poser's and McDonald's criteria and to assess MRI scans according to the McDonald's guidelines.
In terms of the kappa statistic (k), we found a moderate agreement on the overall diagnosis using both Poser's and McDonald's criteria (k, respectively, 0.57 and 0.52).
As for distinct diagnostic categories, we observed a moderate to substantial agreement for the three McDonald categories (range of k values 0.49–0.64) and a fair to substantial agreement for the nine Poser categories (range of k values 0.37–0.67).
Taking into account clinical information, the agreement on dissemination over time was substantially higher (k=0.69) than that found on dissemination over space (k=0.46).
In contrast, for MRI assessment, the agreement for spatial dissemination was substantial (k=0.74) compared with the fair agreement (k= 0.25) yielded by dissemination over time.
The new McDonald's criteria yield a good overall diagnostic reliability, and compare favourably with Poser's classification in terms of agreement on distinct diagnostic categories.