Plateaus in amyotrophic lateral sclerosis progression: results from a population-based cohort.

Abstract

The aim was to assess the frequency of plateaus in amyotrophic lateral sclerosis (ALS) progression using a large population-based cohort. Data from the Piemonte and Valle d'Aosta ALS register were used. Patients who were diagnosed between 2007 and 2014 were considered. The follow-up period was extended until 31 December 2018. Visits after tracheostomy were excluded. A plateau was defined as a stable Amyotrophic Lateral Sclerosis Functional Rating Scale revised (ALSFRSr) score lasting at least 6, 12 or 18months. Out of 1214 patients, 200 (16.5%), 93 (7.7%) and 52 (4.3%) showed at least one plateau lasting a minimum of 6, 12 and 18months, respectively. Plateaus occurred mostly at high ALSFRSr scores and were more frequent during the initial phases of the disease course. Spinal onset [odds ratio (OR) 1.83, 95% confidence interval (CI) 1.16-2.95, P value 0.01) and predominant upper motor neuron phenotype (OR 2.18, 95% CI 1.36-3.48, P value 0.001) conferred a higher risk for the subsequent appearance of plateaus; conversely, older age at diagnosis (OR 0.25, 95% CI 0.11-0.54, P value 0.002 for >75 year age class) reduced this risk. Plateaus in ALS progression lasting at least 6months appear in about one out of six patients and could last even 12, 18months or more in a smaller subgroup of patients. Plateau occurrence should not lead the neurologist to automatically reconsider ALS diagnosis and should be considered for future clinical trial design.