OBJECTIVE: To assess the added prognostic value of the aggregated clinical and 
electrodiagnostic data, which define a given diagnostic category according to 
the Awaji or revised El Escorial criteria at time of diagnosis in patients with 
amyotrophic lateral sclerosis (ALS).
METHODS: Clinical signs and electrodiagnostic test results were collected at 
time of diagnosis in 396 patients with ALS between January 2009 and January 
2016. Significant predictors of prognosis were identified using a univariate 
model, and later combined in a multivariate Cox regression model.
RESULTS: Known factors associated with reduced survival included older age at 
onset, shorter diagnostic delay, higher ALSFRS-R slope and presence of C9orf72 
mutation (all p < 0.05). Diagnostic category according to Awaji (p < 0.0001) or 
to revised El Escorial (p = 0.0177) criteria, definite ALS according to Awaji 
(p < 0.0001) or to revised El Escorial (p = 0.0343) and number of regions with 
LMN involvement (p < 0.0001) were all associated with shorter survival.
DISCUSSION: Clinical and electrodiagnostic data at time of diagnosis provide 
additional prognostic information compared to other known prognostic factors. 
Diagnostic category according to Awaji and the extensiveness of LMN involvement 
contain the most additional value.