Investigate an association with BMI and relapse risk in patients with multiple sclerosis (MS) treated with B cell-depleting therapy.

We previously reported an association of BMI with increased risk of B cell repopulation after treatment with ocrelizumab (Loeffler, Han, AAN 2023). We aimed to assess whether BMI was associated with increased risk of clinical and/or radiographic relapse in the same patient population.

Our study is a retrospective cohort study at a single academic referral center. Patients were identified using ICD billing code. Normal BMI was defined as 18.5-25. Overweight/obese BMI was defined as >25. The primary outcome was clinical and/or radiographic MS relapse. Chi-squared test was used to compare the categorical outcome on the categorical variable of normal vs overweight/obese BMI groups.

405 patients were initially identified. Excluding patients with missing ocrelizumab/lymphocyte subset data, 157 patients were included for detailed chart review. Of these, 57 patients had missing data/were lost to follow up, leaving a total of 100 patients. The median age was 49(SD 13.3). 42 patients had normal BMI(18.5-25) and 58 patients had overweight/obese BMI(>25). The median follow up time was 4.4 years(SD 1.7). A total of 5 patients had a clinical and/or radiographic relapse during the course of their follow up. 2 were in the normal BMI group, 3 in the overweight/obese BMI group. The proportions of patients with relapse were not significantly different.

Our study does not conclude that BMI is associated with clinical and/or radiographic relapse after treatment with ocrelizumab. This parallels a prior prospective study (Signoriello et al, MSRD, 2020). We observed relatively few clinical and/or radiographic relapses. Our study limitations include lower power to detect a relatively rare outcome. Future directions include analysis for other variables that may be associated with risk of relapse after anti-CD20 therapy in a larger retrospective or prospective study.