Time Trajectories of Critical Events in Amyotrophic Lateral Sclerosis Progression
Brian Crum1, F. Safa Erenay3, Kalyan Pasupathy2, Haoran Wu3, Osman Ozaltin4
1Neurology, 2Health Sciences Research, Mayo Clinic, 3Management Sciences, University of Waterloo, 4Industrial and Systems Engineering, North Carolina State University

Estimating time trajectories for critical ALS events (e.g., losing functionality in one arm, requiring wheelchair or other devices) by augmenting public databases using detailed institutional data.


Amyotrophic lateral sclerosis (ALS) causes permanent motor impairments and the need for assistive devices. Estimating the timing of critical ALS events is desired; however, completely pertinent data is not readily available.

Tollgate-based ALS Staging System (TASS) specifies the critical events in ALS progression, i.e., tollgates. We applied logistic regression to predict whether each TASS tollgate is passed given the itemized ALSFRS-R (Revised Amyotrophic Lateral Sclerosis Functional Rating) scores using a longitudinal dataset including 514 ALS patients, seen quarterly at the ALS Clinic of Mayo Clinic-Rochester between 2006-2016. We translated (i.e., mapped) the ALSFRS-R data of 3,264 patients from the PRO-ACT (Pooled Resource Open-Access ALS Clinical Trials Database) database into TASS information. We derived the time trajectories of ALS progression through tollgates from the augmented PRO-ACT data (from ALSFRS-R-to-TASS mapping) using Kaplan-Meier analyses.
The logistic regression approach using Mayo Clinic data accurately estimated tollgate-passed states of patients given their itemized ALSFRS-R scores, e.g., AUC ≥ 0.90. The tollgate time trajectories derived from the augmented PRO-ACT data provide valuable insights; e.g., we predicted that the majority of the ALS patients would have modified arm function (67%) and require assistive devices for walking (53%) by the second year after ALS onset. By the third year, most (74%) ALS patients would occasionally use a wheelchair, and 48% of the ALS patients would be wheelchair-dependent by the fourth year. Assistive speech devices and feeding tubes were needed in 49% and 30% by the third year after the disease onset, respectively.

The estimated time trajectories assist clinicians in better understanding general ALS progression pathways, while extending these estimations to various risk subgroups in future studies may facilitate personalized ALS management.