Epidemiology of amyotrophic lateral sclerosis and effect of riluzole on disease course

To assess the epidemiology of ALS in Austria and to evaluate the long-term effect of riluzole treatment on survival.

Hospital discharge and riluzole prescription databases were used to identify ALS cases from January 2008 to June 2012. Using the capture-recapture method we evaluated the incidence and prevalence of ALS and patients' survival in dependence of age, gender and riluzole treatment.

The corrected incidence and prevalence of ALS were 3.13/100,000 person-years (95% CI, 2.77 to 3.50) and 9.14/100,000 persons (95% CI, 8.53 to 9.79), respectively. Median survival from diagnosis was 676 days (95% CI, 591 to 761). A younger age at diagnosis was associated with a longer survival. Gender did not appear to affect survival time. Riluzole therapy was associated with a survival advantage only for the initial treatment period. The adjusted hazard ratio of mortality for using riluzole increased continually over time resulting in an apparent reversal of its beneficial effect after 6 months of therapy.

We report incidence and prevalence estimates that are on the upper end of the wide range discussed in literature. Riluzole seems to exert a beneficial effect only in the first 6 months of therapy.