Early initiation of riluzole may improve absolute survival in amyotrophic lateral sclerosis.

INTRODUCTION/AIMS: Riluzole improves survival in amyotrophic lateral sclerosis (ALS), but optimal time and duration of treatment are unknown. The aim of this study was to examine if timing of riluzole initiation and duration of treatment modified its effect on survival. METHODS: Patients from the PRO-ACT dataset with information on ALS Functional Rating Scale, time from onset to enrollment (TFOE), and riluzole use were selected for analysis. Survival from enrollment was the outcome. Multivariable Cox proportional hazard models were examined for interactions between riluzole and TFOE. Inverse probability of treatment weighting (IPTW) was used to assess average treatment effect. RESULTS: Of 4778 patients, 3446 (72.1%) had received riluzole. In unadjusted analyses, riluzole improved median survival significantly (22.6 vs. 20.2 months, log-rank p < 0.001). In multivariable analyses, no significant interaction between TFOE and riluzole was found. Riluzole effect was uniform during follow-up. By IPTW, estimated riluzole hazard ratio was 0.798 (95% confidence interval 0.686-0.927). Delaying riluzole initiation by 1 y (6 to 18 months from onset) may translate to reducing median survival from onset by 1.9 months (40.1 to 38.2 months). DISCUSSION: Riluzole appears to reduce risk of death uniformly, regardless of time from onset to treatment, and duration of treatment. Earlier treatment with riluzole may be associated with greater absolute survival gain from onset. Early diagnosis of ALS will facilitate early treatment and is expected to improve survival.