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March 2007

Slower Disease Progression and Prolonged Survival in Contemporary Patients With Amyotrophic Lateral Sclerosis—Reply

Arch Neurol. 2007;64(3):459. doi:10.1001/archneur.64.3.459

In reply

We thank Drs Kano, Arasaki, Ikeda, and Iwasaki for their comments on our study.1 It is gratifying that in a Japanese population of patients with ALS, these investigators reached the same conclusion we had reached, namely that contemporary patients appear to have slower disease progression than patients seen prior to the year 2001. Even the diagnostic delay noted in the contemporary Japanese population is in accord with this conclusion. In a previous publication, we noted that one of the key factors influencing survival in our ALS population was the delay in referral to our ALS clinic.2 The greater the delay, the longer the survival. This finding was possibly related to the fact that patients with slow moving disease were more likely to delay visits to our clinic. In a more recent study, we were able to demonstrate that the diagnostic delay (measured as the time between first symptom and first examination) influenced disease progression as well as survival. We noted that patients with ALS examined by us for the first time more than 12 months after their first symptoms progressed more slowly than patients first examined less than 12 months after their first symptoms.3 The key question is how to explain this recent change in rate of progression and survival. None of the factors we examined provided a convincing answer, but we would agree that life style and/or environmental changes are likely candidates and merit detailed study.