Supplementary Material for: Epidemiology of Amyotrophic Lateral Sclerosis and Effect of Riluzole on Disease Course

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