Gender Effects on Intramuscular Interferon Beta-1a in Relapsing-remitting Multiple Sclerosis: Analysis of 1406 Patients

Background: We aimed to evaluate effects of gender on efficacy and safety of intramuscular (IM) interferon beta (IFNβ)-1a in patients with relapsing-remitting MS (RRMS) or clinically isolated syndromes (CIS) characteristic of early MS.

Methods: Pooled data from 1406 (1027 women; 379 men) patients enrolled in five clinical studies of IM IFNβ-1a were analyzed. One analysis examined data for all patients treated with IM IFNβ-1a from all studies. Separate analyses were conducted of pooled IM IFNβ-1a-treated groups from all studies and pooled IFNβ-1a-treated and placebo-treated patients from the placebo-controlled studies. Outcome measures included time to first relapse, annualized relapse rate, time to disability progression, number of gadolinium-enhanced lesions, adverse events, laboratory evaluations, and neutralizing antibodies.

Results: All efficacy assessments indicated similar treatment effects of IM IFNβ-1a in men and women with no significant treatment-by-gender interactions. Women reported more headaches, urinary tract infections, and depression in the analysis; however, these were also common in women who received placebo. Men reported more frequent flu-like symptoms in the placebo-controlled studies only. There were no other differences in the safety profile of IM IFNβ-1a between men and women.

Conclusions: We conclude that no significant gender-related differences were found in the efficacy and safety of IM IFNβ-1a in patients with RRMS or CIS.