[Epidemiological characteristics of multiple sclerosis in Russia].

An increase in multiple sclerosis (MS) frequency was registered in several countries including Russia. This may be associated with better MS diagnosis and treatment, better data collection and real increase in MS incidence. Previous local studies sometimes were based on mainly hospital cases, so the real prevalence was underestimated. Several population-based studies showed that Russia is in the zone of medium MS risk. In 1999-2000, 24 local medical committees collected the "official" data on the number of resident MS patients, which varied greatly. Statistical analyses showed a significant negative association (R = -0.68) between estimated level of MS prevalence and the percent of severe cases among these MS patients. It is proposed that in several regions the number of mild MS cases had been underestimated and thus the percent of severe cases was high. Using the rates, received in large population-based studies in different countries, we re-calculated the data using the 33% rate of severe MS cases as a model. The calculated "model" indexes using "official" data in two Russian cities Moscow and Orel (40.8 and 64.8 cases per 100,000 of population) were very close to what had been found in these populations in population-based epidemiological studies (37.8 and 66.1 cases, respectively). Recalculation of the "official" data from all 24 regions showed, that the "model" MS prevalence in different regions of Russia varied from 35 till 70 cases per 100,000 of population, which seems real taking into consideration the geographical factor and the ethnic origin of these populations (percents of European residents). These "model" numbers may be used before the already started all-over-country epidemiological study will be finished.