Timing of high-efficacy therapy initiation in multiple sclerosis: a multicenter real-world analysis from Argentina

Early initiation of high-efficacy therapies (HETs) in relapsing-remitting multiple sclerosis (RRMS) is associated with improved long-term outcomes, yet real-world treatment trajectories may not reflect this paradigm. We aimed to quantify delays in diagnosis and treatment initiation in RRMS and assess whether these differ across first-line strategies in Argentina.

We conducted a multicenter registry-based study including treatment-naïve RRMS patients from the Argentine Multiple Sclerosis Registry (RelevarEM). Three intervals were evaluated: symptom-to-diagnosis/treatment indication (T1), diagnosis/treatment indication-to-treatment initiation (T2), and symptom-to-treatment initiation (T3). Delays were compared across oral, injectable, and high-efficacy therapies using descriptive analyses and multivariable accelerated failure time models adjusted for demographic, clinical, and healthcare-related factors.

A total of 389 patients were included. The interval from diagnosis/treatment indication to treatment initiation (T2) was comparatively similar across groups (approximately 1-2 months). In contrast, the symptom-to-treatment interval (T3) was longer among patients initiating HETs versus oral therapies (adjusted median 9.13 vs 2.58 months; +6.54 months), with the excess time concentrated predominantly before the recorded diagnosis/treatment-indication milestone. Sensitivity analyses suggested heterogeneity within HETs.

These findings suggest that the longer time to HET initiation is primarily attributable to the interval preceding the recorded diagnosis/treatment-indication milestone, whereas the subsequent interval to treatment initiation was comparatively similar across treatment classes.