Characterising ALS disease progression according to El Escorial and Gold Coast criteria

Background The Gold Coast criteria (GCC) have been proposed as a means of selecting patients for amyotrophic lateral sclerosis (ALS) clinical trials. We aimed to characterise disease progression according to the GCC. Methods Data from population-based ALS registries from the Netherlands and Belgium were analysed. The GCC additionally define ALS as lower motor neuron (LMN) dysfunction in >= 2 body regions without upper motor neuron dysfunction. Therefore, the revised El Escorial criteria (rEEC) were supplemented with a 'Gold Coast ALS' category for patients with only LMN dysfunction in >= 2 body regions. We assessed survival time, ALS Functional Rating Scale (ALSFRS-R) progression rates and between-patient variability per diagnostic category. Results We included 5957 ALS patients, of whom 600 (10.1%) fulfilled the GCC but not the rEEC, and 95 (1.6%) fulfilled only the rEEC. ALSFRS-R progression rates were similar for the rEEC (0.84 points/month) and GCC (0.81 points/month) with similar variability (standard deviation of 0.59 vs. 0.60) and median survival time (17.8 vs.18.7 months). Survival time and average progression rates varied (p<0.001) between categories. Per category, however, there was considerable between-patient variability with progression rates ranging from: -2.10 to -0.14 (definite), -1.94 to -0.06 (probable), -2.10 to -0.02 (probable laboratory supported), -1.79 to -0.02 (possible) and -1.31 to 0.08 (Gold Coast). Conclusions The GCC broaden the definition of ALS, allowing more patients to participate in trials, while minimally impacting population heterogeneity. Given the large variability per diagnostic category, selecting only specific categories for trials may not result in a more homogeneous study population.