Assessing disease progression in ALS: prognostic subgroups and outliers

Area of Science:

• Neurology
• Biomarkers
• Prognostics

Background:

• The ALS Functional Rating Scale-Revised (ALSFRS-R) decline from symptom onset to diagnosis (ΔFS) is a validated prognostic biomarker for Amyotrophic Lateral Sclerosis (ALS) survival.
• Understanding survival deviations from ΔFS-defined prognosis is crucial for patient care.

Purpose of the Study:

• To categorize a large ALS patient cohort based on initial ΔFS.
• To investigate survival outcomes deviating from ΔFS-based prognostic expectations.

Main Methods:

• Stratified 1056 ALS patients into slow, intermediate, and fast progressors using ΔFS percentiles.
• Classified survival into short (<2 years), average (2-5 years), and long (>5 years) outcomes.
• Analyzed clinical and demographic characteristics within subgroups.

Main Results:

• ΔFS stratification identified progression categories with cutoffs <0.29, 0.29-1.03, and >1.03 points/month.
• Long survivors constituted 26%, while 21% were short survivors.
• Observed discrepancies: 6% of fast progressors lived >5 years, and 13% of intermediate progressors lived <2 years, unexplained by analyzed factors.

Conclusions:

• Reaffirmed ΔFS as a prognostic biomarker for ALS survival.
• Identified patient outliers defying ΔFS-based survival predictions.
• Highlighted the non-linear nature of ALS progression, potentially influenced by genetic or unknown biological factors requiring further research.