Improving the measurement properties of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R): deriving a valid measurement total for the calculation of change.

Young, Carolyn A ORCID: 0000-0001-6971-8203, Chaouch, Amina, Mcdermott, Christopher J, Al-Chalabi, Ammar, Chhetri, Suresh K, Talbot, Kevin, Malaspina, Andrea, Mills, Roger ORCID: 0000-0001-6341-6220 and Tennant, Alan (2024) Improving the measurement properties of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R): deriving a valid measurement total for the calculation of change. Amyotrophic lateral sclerosis & frontotemporal degeneration, 25 (3-4). pp. 1-10.

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Official URL: http://dx.doi.org/10.1080/21678421.2024.2322539

Abstract

<h4>Background</h4>The Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) total score is a widely used measure of functional status in Amyotrophic Lateral Sclerosis/Motor Neuron Disease (ALS), but recent evidence has raised doubts about its validity. The objective was to examine the measurement properties of the ALSFRS-R, aiming to produce valid measurement from all 12 scale items.<h4>Method</h4>Longitudinal ALSFRS-R data were collected between 2013-2020 from 1120 people with ALS recruited from 35 centers, together with other scales in the Trajectories of Outcomes in Neurological Conditions-ALS (TONiC-ALS) study. The ALSFRS-R was analyzed by confirmatory factor analysis (CFA), Rasch Analysis (RA) and Mokken scaling.<h4>Results</h4>No definite factor structure of the ALSFRS-R was confirmed by CFA. RA revealed the raw score total to be invalid even at the ordinal level because of multidimensionality; valid interval level subscale measures could be found for the Bulbar, Fine-Motor and Gross-Motor domains but the Respiratory domain was only valid at an ordinal level. All four domains resolved into a single valid, interval level measure by using a bifactor RA. The smallest detectable difference was 10.4% of the range of the interval scale.<h4>Conclusion</h4>A total ALSFRS-R ordinal raw score can lead to inferential bias in clinical trial results due to its non-linear nature. On the interval level transformation, more than 5 points difference is required before a statistically significant detectable difference can be observed. Transformation to interval level data should be mandatory in clinical trials.

Item Type:	Article
Uncontrolled Keywords:	Humans, Amyotrophic Lateral Sclerosis, Disease Progression, Factor Analysis, Statistical
Divisions:	Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology
Depositing User:	Symplectic Admin
Date Deposited:	15 Apr 2024 09:24
Last Modified:	26 Apr 2024 20:26
DOI:	10.1080/21678421.2024.2322539
Open Access URL:	https://doi.org/10.1080/21678421.2024.2322539
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3180327