Multiple Sclerosis in the Emergency Department: A Retrospective Case-Control Study in a Large US Center.

Background and objectives: The reasons for people with multiple sclerosis (MS) to access emergency services are understudied in the era of high-efficacy disease-modifying therapies (DMTs). Many people with MS live with multiple comorbidities and/or experience social determinants of health, which may affect their emergency department (ED) use. The aim of this study was to identify the reasons and risk factors for ED visits among patients with known MS, including sociodemographic characteristics, comorbidity burden, and DMT efficacy category.

Methods: A retrospective case-control study was conducted at the Massachusetts General Hospital, Boston. Patients with MS were analyzed in a 1:2 ratio of cases (patients with at least one ED visit) and controls (no ED visits) during the study time frame June 2019-December 2023. Regression models were constructed to assess the association of predefined variables-sex, age, race, insurance type, comorbidities as a Charlson Comorbidity Index (CCI), and DMT efficacy category-with the likelihood of an ED visit.

Results: Of 1,462 evaluated people with MS, 900 were randomly selected and included: 300 cases and 600 controls. Most patients were female (70.7% cases, 74.7% controls) and White (79.0% cases, 87.2% controls). Cases had a higher mean CCI score (0.83 points) compared with controls (0.05 points). Many people with MS were not taking a DMT (64.3% cases, 39.5% controls). ED utilization showed that 52.0% of patients had a single visit, with COVID-19 being the most common diagnosis (4.2%). 10.3% of people with MS who went to the ED had more than 5 visits during the study time frame. In a multivariable model, higher CCI score was the strongest predictor of ED visits (odds ratio [OR] = 4.23, p < 0.001). No DMT use (OR = 2.56, p < 0.001) and having public or no insurance (OR = 1.99, p < 0.001) each increased the likelihood of an ED visit while identifying as a racial minority led to a lower likelihood of an ED visit (OR = 0.48, p = 0.006).

Discussion: Specific risk factors for ED use occur in people with known MS. Comprehensive management of comorbidities and clinical pathways to reassess the high number of people with MS in the ED who do not take a DMT should be considered.