Risk factors for development of lymphopenia in dimethyl fumarate-treated patients with multiple sclerosis.

BACKGROUND: Dimethyl fumarate (DMF, Tecfidera®) is a first-line disease-modifying therapy for relapsing-remitting multiple sclerosis. Lymphopenia is a frequent reason for discontinuation in fumarate-treated patients. Management strategies to minimize risk of lymphopenia are warranted. OBJECTIVE: The aims of this study were to investigate the correlation of body mass index (BMI), baseline absolute lymphocyte count (ALC), age and sex with risk of DMF-induced lymphopenia in MS patients. METHODS: The study was a retrospective cohort study of 452 MS patients who had been prescribed DMF at six clinics in two Danish regions between May 2014 and September 2017. Data on lymphocyte counts, BMI, age, sex, and reason for discontinuation of DMF were collected through the Danish Multiple Sclerosis Registry, with follow- up to two years after treatment start. RESULTS: 28.5% of patients had lymphopenia grade II or higher at some time in the first two years of DMF treatment. Increased risk of lymphopenia was observed in patients with baseline ALC of 1.00-1.49×109 cells/L (odds ratio, OR 5.48, p<0.0001) and 1.50-1.99×109 cells/L (OR 2.08, p = 0.0009). Reduced risk of lymphopenia was observed in patients with ALC of 2.00-2.49×109 cells/L (OR 0.51, p< 0.01) and ≥ 2.50×109 cells/L (0.12, p<0.0001). Patients aged ≥ 56 years had an increased risk of lymphopenia (OR 3.58, p<0.001), and patients with BMI ≥ 30 kg/m2 had a decreased risk of lymphopenia (OR 0.53, p value = 0.03). CONCLUSION: Low baseline ALC and older age were risk factors for DMF-induced lymphopenia, while BMI ≥ 30 kg/m2 and high baseline ALC were protective factors for developing lymphopenia in MS patients treated with DMF.

Comparative effectiveness of teriflunomide and dimethyl fumarate: A nationwide cohort study.

OBJECTIVE: To compare on-treatment efficacy and discontinuation outcomes in teriflunomide (TFL) and dimethyl fumarate (DMF) in the treatment of relapsing-remitting multiple sclerosis (RRMS) in a real-world setting. METHODS: We identified all patients starting TFL or DMF from the Danish Multiple Sclerosis Registry and compared on-treatment efficacy outcomes between DMF using TFL, adjusted for clinical baseline variables and propensity score-based methods. RESULTS: We included 2,236 patients in the study: 1,469 patients on TFL and 767 on DMF. Annualized relapse rates (ARRs) in TFL and DMF were 0.16 (95% confidence interval [CI] 0.13-0.20) and 0.09 (95% CI 0.07-0.12), respectively. Relapse rate ratio for DMF/TFL was 0.58 (95% CI 0.46-0.73, p < 0.001). DMF had a higher relapse-free survival proportion at 48 months of follow-up (p < 0.05). We observed no difference in Expanded Disability Status Scale score worsening. Discontinuations due to disease breakthrough were 10.2% (95% CI 7.6%-12.8%) and 22.1% (95% CI 19.2%-25.0%) for DMF and TFL, respectively. A subgroup analysis of ARRs in 708 patients with available baseline MRI T2 lesion amount reported similar results after adjustment. CONCLUSION: We found lower ARR, higher relapse-free survival, and lower incidence of discontinuation due to disease breakthrough on treatment with DMF compared with TFL. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with RRMS, DMF is more effective in preventing relapses and has lower discontinuation due to disease breakthrough compared with TFL.