Initial lymphocyte count and low BMI may affect fingolimod-induced lymphopenia.
OBJECTIVE
To assess whether pretreatment-lymphocyte counts, treatment before fingolimod, age, sex, or body mass index (BMI) affects the risk of fingolimod-induced lymphopenia in patients with relapsing-remitting multiple sclerosis (RRMS).


METHODS
Data were obtained from a German multicenter, single-arm, open-label study of patients with RRMS treated with fingolimod, and findings were validated in an independent Swedish national pharmacovigilance study.


RESULTS
Four hundred eighteen patients with RRMS from Germany and 438 patients from Sweden were included. A nadir ≤0.2 × 10(9) lymphocytes/L was reached in 15% (95% confidence interval [CI] 12%-17%) of all 856 patients. Patients with lower starting lymphocyte counts (below 1.6 × 10(9)/L) and patients with BMI lower than 18.5 kg/m(2) (women only) were at higher risk of developing lymphopenia with values ≤0.2 × 10(9)/L in the combined analysis, increasing the risk in these subgroups to 26% (95% CI 20%-31%) or 46% (95% CI 23%-71%), respectively. In the German cohort, infection rates were similar in patients who developed severe lymphopenia and those who did not.


CONCLUSIONS
Our findings suggest that patients with low baseline lymphocyte counts and underweight women in which fingolimod treatment will be initiated should possibly be monitored more closely.