Bariatric surgery outcomes in multiple sclerosis: Interplay with vitamin D and chronic pain syndromes.

BACKGROUND: Obesity and lower vitamin D levels are associated with adverse outcomes in multiple sclerosis (MS). Bariatric surgery is a safe intervention in patients with MS, although it lowers vitamin D levels in the general population. OBJECTIVE: To investigate the effects of bariatric surgery on vitamin D levels and interrogate risk factors for unsuccessful post-operative weight loss in patients with MS. METHODS: We retrospectively identified patients with MS who underwent bariatric surgery from 2001 to 2023. Wilcoxon signed rank tests for paired samples were used to compare pre- and post-operative body mass index (BMI), expanded disability status scale (EDSS), timed 25-foot walk (T25FW), and median vitamin D values. RESULTS: Following bariatric surgery, patients with MS had a decrease in BMI (mean percent total weight loss of 18.4 %, range 0-38 %, p < 0.001) and an increase in vitamin D values (mean increase of 23 ng/mL, range -4-32 ng/mL, p < 0.001), while no change in EDSS or T25FW was seen. Four out of 20 patients did not lose more than 5 % of their pre-operative BMI, all of whom had chronic pain syndromes and were on gabapentin. CONCLUSION: Healthy vitamin D levels are attainable following bariatric surgery in patients with MS.