Autoimmune comorbidities in persons with multiple sclerosis in the population of Belgrade

Aim of the paper: To analyze the burden of autoimmune comorbidities in persons with multiple sclerosis (PwMS) in Belgrade, Serbia, using the population-based MS Registry. Methods: A descriptive epidemiological study was used. The source of data was the Belgrade population MS Registry. The prevalence of different autoimmune comorbidities was calculated as the proportion of persons with a certain comorbidity among the total MS cohort in the Registry and presented with corresponding 95% Confidence Interval (CI). The prevalence date used was December 31st, 2021. Results: The prevalence of all autoimmune comorbidities was 5.80% (95% CI 4.98-6.73) i.e. the total of 165 autoimmune comorbidities were registered in 2841 PwMS in the Belgrade Registry on December 31, 2021. The highest prevalence was observed in autoimmune thyroid disease (4.26%, 95% CI 3.55-5.07). The highest prevalence was observed in the age groups 50-59 and 60-69 years, with higher values observed in women of all ages. Age-adjusted prevalence of autoimmune comorbidities was 0.05/100,000 in both sexes, 0.03/100,000 in males and 0.07/100,000 in females. In persons with relapsing MS phenotype prevalence of autoimmune comorbidities was 5.5%, while in persons with primary progressive MS phenotype it was 4.9%, however, this difference was not statistically significant (ch2=5.118; p=0.163). Conclusion: The results of our study showed that the prevalence of autoimmune comorbidities in PwMS in Belgrade, Serbia, is in accordance with that observed in other studies. As expected, the prevalence increased with age and was higher in females. The most common autoimmune comorbidity was the autoimmune thyroid disease.