Modification of the ALSFRS-R for Utilization in Individuals Not Using Noninvasive Ventilation

The Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) is widely employed in assessing functional decline in individuals with amyotrophic lateral sclerosis (ALS). A limitation of the scale is that item 12 does not directly evaluate worsening respiratory failure in ALS but rather the management thereof as a surrogate marker. We propose an alternative scale to assess respiratory function in ALS individuals who do not use noninvasive ventilation (NIV).

85 participants were included in the study. ALSFRS-R scores were calculated and FVC measured at each clinic visit. Additional questions were asked regarding the presence of nocturnal hypoventilation symptoms, including (1) early-morning headaches, (2) excessive daytime somnolence, (3) poor concentration, and (4) decrease in appetite. A nocturnal hypoventilation item was developed using these questions in participants not using NIV. Internal consistency and validity were calculated using the nocturnal hypoventilation item as substitute for the existing item 12. The ALSFRS-R was modified by adding the alternative item 12 and named ALSFRS-Revised Modified (ALSFRS-RM).

The ALSFRS-RM has a strong internal consistency and validity, which was calculated using Cronbach alpha and factor analysis. A Spearman correlation of 0.34 was calculated between the measured FVC and the nocturnal hypoventilation item score. In addition, a nocturnal hypoventilation item score of ≤ 3 corresponds to an FVC of ≤ 65%, with the upper 95% CI < 80%.

Our results suggest that the addition of an alternative item 12 to the existing ALSFRS-R may be a viable option for use in individuals not receiving ventilatory support. The new nocturnal hypoventilation item may also be a reliable indicator of respiratory decline that may remove the need for FVC measurement prior to introducing NIV.