The epidemiology of MS is rapidly changing in many parts of the world. Since 1990s, many epidemiological studies have classified Russia as a low-moderate-risk area for MS. Changes in the availability of MRI and the organization of specialized care services have led to a significant improvement in the diagnosis of the disease. The introduction of a disease modifying therapy support system has also made a significant contribution to the changing of the epidemiology. Yaroslavl is a city and the administrative center of Yaroslavl Oblast, Russia, located 250 kilometers (160 mi) northeast of Moscow, medium size industrial city with nearly 600,000 residents.
to determine the difference in prevalence and incidence rates of MS and clinical representation in 1999 and 2019 in city of Yaroslavl (Central Russia region).
This cross-sectional study was conducted between 1997 and 2020. Patients with a diagnosis of MS according to 1993 Poser criteria (1999, with MRI control) and 2010 revised McDonald criteria (2019) were identified. Prevalence was defined as the total number of patients with a diagnosis of MS per 100,000 inhabitants, while the incidence was defined as the number of new cases diagnosed with MS per 100,000 individuals. All rates were calculated with emphasis on age range and gender, standardized by European population.
Two hundred and fifty-seven patients with MS who had experienced the clinical onset of the disease before 31 December 1999 and 479 patients with onset before 31 December 2019 were found. The prevalence rate was 42.6/100,000 [95% confidence interval (CI) 40.3–45.0] and 72,3/100,000 (95% CI 69.8-75.2), respectively (+84%, p=0.002). The mean annual prevalence from 1995 to 1999 was 1,6 (95% CI 1.4-1.9). From 2014 to 2018, 109 patients with MS had clinical onset of the disease. The mean annual incidence was 3.3/100,000 (95% CI 2.7–4.1), so we have a 207 per cent growth. Sex ratio (male:female) is also changed from 1,52:1 to 2,49:1 The mean length of time between the date of clinical onset and the date of the diagnosis was 1.4 ± 1.7 years. Symptoms of MS onset changed from motor (47.4%) and optic neuropathy (16.8%) in 1999 to optic (25.3%) and brainstem (20.6%) in 2019.
Incidence rates have further increased in Yaroslavl population, suggesting that the risk of MS is still increasing. Now Yaroslavl city approaching to be considered a high-risk area for MS.