RESUMO
Work objective - to study the relationship between the duration of remission after the onset, the severity of relapses against the background of different duration of the relapsing stage (RS) and the nature of the prognosis in the secondary progressive multiple sclerosis (SPMS) using clinical and mathematical analysis. Patients with different prognosis for SPMS; neurological examination using The Expanded Disability Status Scale (EDSS); a survey method. Mathematical methods: 'contingency tables 2x2' (determining the significance of the connection between a pair of two indicators - different duration of remission after the onset and RS in four groups of patients), Yule's Coefficient of Association (determining the magnitude of differences between the group and the studied indicator), a permutation test (defining clinical indicators on RS, which significantly differed in mild and severe relapses). Pairwise comparison in four groups of patients with different duration of remission after the onset and RS in SPMS showed that long-term remission after the onset and prolonged RS delay the transition of RS into secondary progression (SP). Short duration of these indicators revealed the opposite prognostic tendencies, indicating the further progression of the disease. The presence of severe relapses on RS in SPMS is predominantly associated with unfavorable prognostic indicators on RS and indicates the initiation of the transition into SP. Accordingly, the duration of remission after the onset, the severity of relapses against the background of different durations of RS should be regarded as prognostic clinical markers that play a key role in the switch of RS to SPS in SPMS. The results obtained should be used to assess the current clinical situation and timely prescribe an appropriate pathogenetic therapy on RS.