Three-year clinical outcomes of relapsing multiple sclerosis patients treated with dimethyl fumarate in a United States community health center.

BACKGROUND

Following approval of dimethyl fumarate (DMF), we established a registry of relapsing multiple sclerosis (RMS) patients taking DMF at our community MS center.

OBJECTIVE

To track DMF patients' tolerability, disease progression, and lymphopenia.

METHODS

Patients prescribed DMF for RMS from March 2013 to March 2016 were prospectively enrolled ( N = 412). Baseline data, clinical relapses, magnetic resonance imaging (MRI) activity, discontinuation, and lymphocyte counts were captured through chart review.

RESULTS

The mean age of patients starting DMF was 49.4 ± 12.0 years and 70% transitioned from a previous disease-modifying therapy (DMT). Of the patients, 38% discontinued DMF, 76% of whom discontinued due to side effects. Clinical relapse and MRI activity were low. Comparing patients who transitioned from interferon-β (IFN), glatiramer acetate (GA), or natalizumab (NTZ), patients previously on NTZ had higher rates of relapse than those previously on GA (annualized relapse rate p = 0.039, percent relapse p = 0.021). Grade III lymphopenia developed in 11% of patients. Lymphopenia was associated with older age ( p < 0.001) and longer disease duration ( p < 0.001).

CONCLUSION

Given the high rates of lymphopenia and discontinuation, it has become our clinical practice to more closely scrutinize older patients and those with a longer disease duration who are potential candidates for initiating DMF therapy.