Table 4.

Grouping of exploratory covariates

Grouping	Assessment or data included	Impairment thresholds
Attitudes	ACT-Q (Attitudes towards Clinical Trial Participation Questionnaire)	Not applicable
Quality of life	CDC HQOL-4 (Centre for Disease Control and Prevention-Health-Related Quality of Life)33	Not applicable
	ALSSQOL-20 (ALS-Specific Quality of Life Questionnaire-Brief Form)32
Cognitive impairment	ECAS (Edinburgh Cognitive and Behavioural ALS Screen)36	Total score is 136 where a higher score indicates better performance. Scores below 105 are considered abnormal
Behavioural change	b-DAS (Brief Dimensional Apathy Scale)34 35	Each subscale has a minimum score of 0 (least apathy) and a maximum score of 9 (most apathy)
		Impairment defined as score per subscale:
		Executive ≥4
		Emotional ≥5
		Initiation ≥6
	ECAS Behavioural Screen Subscale	Carer-completed behavioural change screen
		Indicate yes/no to symptoms, score 1 for every symptoms present out of 10
		Carer-completed psychosis screen
		Indicate yes/no to symptoms, score 1 for every symptoms present out of 3
Physical functioning	ALS-FRS (R) (Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised)14	Twelve tasks rated from 0 (cannot do) to 4 (normal ability). Summed score between 0 (worst) and 48 (best)
Neuropsychiatric	HADS (Hospital Anxiety and Depression Scale)27 28	Maximum total score is 24
		Total of 12 per subscale
		(≥9) Severe
		(7–8) Moderate
		(≤6) Mild
	STAI-Y (State-Trait Anxiety Inventory-Form Y)29	Total score ranges 20–80
		(≥60) High
		(40–59) Moderate
		(20–39) Low
	PHQ-9 (9-Item Patient Health Questionnaire)30 31	Depression:
		Total score ranges from 0 to 27
		(20–27) Severe
		(15–19) Moderately severe
		(10–14) Moderate
		(5–9) Mild
		(1–4) Minimal
		Suicidality:
		Item 9 scores from (0) not at all
		1. Several days
		2. More than half the days
		3. Nearly every day
		Scores of >1 indicates presence of suicidal ideation
Clinical phenotype	MND classification	Not applicable
	Site of onset (spinal, bulbar, pure respiratory)
	Age at diagnosis

MND, motor neuron disease.