Patient characteristics in observational studies of the relative risk of infection in people using diseases-modifying treatments for multiple sclerosis

Abstract

Introduction Multiple sclerosis (MS) is a chronic autoimmune disease. Infection is one of the commonly reported outcomes in patients who are under disease-modifying treatments (DMTs). The Influence of patient characteristics on risk of infection was well documented in clinical trials. However, the understanding of patient characteristics and their impact on treatment outcomes in real-world settings, particularly in observational studies, remains limited. Objective To examine patient characteristics like demographics, geographical factors, and socioeconomic factors in observational studies investigating the relative risk of infection among individuals on DMTs for MS. Methods A systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We included observational studies that examined the impact of DMTs use on the occurrence of infection in the MS population. A search was performed in PubMed and Embase and key patient characteristics were extracted from the included studies. Results A total of 30 studies were included in the final analysis. The sample size ranged from 56 to 15,375 participants. The mean age of the study participants ranged from 24.5 to 54.4 years. The proportion of women ranged from 60% to 100%. The geographic representation of the included studies are Americas, Europe, the Middle East, and Oceania. The disease duration ranged from 2 to 17.7 years. Ethnicity, Expanded Disability Status Score (EDSS), Socio-Economic Status (SES), and treatment history were missing in many studies. Conclusion Within this sub-group, our findings indicate that people who are under DMTs for MS consists of younger adults and a higher proportion of women. The reporting of patient characteristics such as ethnicity, SES, EDSS score, and previous use of DMTs were inconsistently reported in the observational studies. This highlights the need for a standardised reporting structure to gain a better understanding of the specific patient characteristics that are associated with infectious risk.