Amyotrophic lateral sclerosis (ALS) is a disease that causes progressive degeneration of neurons present in the spinal cord and cerebral cortex. It is a disease with a progressive course, with worsening disability and death 3 to 5 years after diagnosis. However, some patients seem to have a slower progression, while others maintain a rapid progression, which may influence the clinical course of the disease and accelerate death.

To evaluate the survival time of patients with ALS, according to the progression of the disease in rapid or slow, and to compare the level of functionality between two evaluations.

A longitudinal case series study that followed patients with a confirmed diagnosis of ALS from August 2018 to February 2022. Data were collected from medical records of periodic evaluations, in which pulmonary function tests were performed and the ALS Functional Assessment Scale (ALSFRS-r) was applied. From the values obtained in the scale, the progression rate was calculated, where the patients were divided into slow or rapid progression and followed for 3.5 years for statistical analysis of survival, later performed by the Kaplan-Meyer test. The results of the scores of the first and second evaluation of each patient were compared using the paired t-test.

11 patients were followed, 7 with rapid progression (63%) and 4 slow (37%) with a mean age of 61.64 years and forced vital capacity (FVC): 62.2 (38.7-85.7)%pred. In the functionality evaluation, it was observed that there was a significant reduction (p<0.01) in the total scale score compared to the first evaluation. The survival percentage was 0%, where all patients died at the end of the study, but the median survival of the slow progression group from the first evaluation until the final outcome was 46 months, while the rapid progression group was 28 months, with no significant difference between the survival curves (HR = 0.42; CI 0.12 - 1.48).

The present study was able to demonstrate that after the second evaluation ALS patients may have significant losses of functionality by the decline of the ALSFRS-r functional score. Also, it can determine the evolution of the disease and assist in identifying the speed of progression of the pathology.

Regular use of the ALS functional assessment scale and calculation of the rate of progression in the outpatient clinical setting becomes essential to chart a better short- and long-term prognosis and follow-up of the disease.