Table 1.

Variables/Measures Organized by the International Classification of Functioning, Disability and Health

ICF domain	Variable	Measure	# of items	Focus and Scoring	Studies providing measurement evidence
Dependent variable
Participation	Frequency	Late Life Disability Instrument24	16	The frequency of participating in two role domains (social and personal). Response scale: 1 (never) to 5 (very often). 0 to 100: Higher scores indicate more frequent participation.	Older adults24,26 Older wheelchair-users27
Independent variable of interest
Body function	Self-efficacy	Wheelchair Use Confidence Scale17	65	Self-efficacy in six areas including maneuvering around the physical environment, performing activities, knowledge of the wheelchair and solving problems, social situations, advocacy, and emotions. Response scale: 0 (low) to 100 (high). 0 to 100: Higher scores indicate more self-efficacy.	Wheelchair-users17
Potential confounding variables
Personal factors	Comorbidities	Functional Comorbidity Index30	18	Participants respond as either yes or no when asked if a doctor has diagnosed them with any of the 18 health conditions. 0 to 18: Higher scores indicate more comorbidities.	Spine patients30
Environmental factors	Need for a seating intervention	Seating Identification Tool31	11	Participants respond as either yes or no when asked about pressure, discomfort behaviours, mobility, positioning, and stability. 0 to 15: Higher scores indicate more issues with the wheelchair.	Wheelchair-users31
	Social support	Interpersonal Support and Evaluation List-632	6	Perceived social support is rated on scale ranging from 0 (definitely false) to 3 (definitely true). 0 to 18: Higher scores indicate more social support	General population32
	Barriers - home	Home and Community Environment Instrument33	8/5	Amount of physical barriers in the home and community are quantified. 0 to 10: Higher scores indicate more home barriers. 0 to 5: Higher scores indicate more community barriers.	Adults with mobility limitations33
Potential mediating variables
Participation	Limitations	Late Life Disability Instrument24	16	The extent of limitation in performing tasks in two role domains (instrumental and management). Response scale: 1 (completely) to 5 (not at all). 0 to 100: Higher scores indicate fewer limitations.	Older adults24 Older wheelchair-users27
Activity	Life-space mobility	Life Space Assessment41	15	Questions pertain to the frequency of movement in five areas (within the home, around the home, in the neighbourhood, in town, and outside of town) over the pastfour weeks, and if any assistance (from other persons or with equipment) was used. 0 to 120: Higher scores indicate more mobility.	Older adults41
	Wheelchair skills	Wheelchair Skills Test – Questionnaire42	32	Participants are asked if they can safely complete a wheelchair skill. Responses are given either a pass or fail. 0 to 100: Higher scores indicate more skills.	Wheelchair-users42
	Activities of daily living	Barthel Index – postal version43	10	Ability to perform activities of daily living are rated. Response scales differ for each item. 0 to 20: Higher scores indicate more ability.	Individuals with stroke43
Body function	Depression/Anxiety	Hospital Anxiety and Depression Scale44	7	Depression and anxiety symptoms experienced during the past week are rated on a scale from 0 (not at all) to 3 (very often indeed). 0 to 21: Higher scores indicate more severe symptoms.	Individuals with a spinal cord injury53
	Pain	Wheelchair User Shoulder Pain Index45	15	The degree of shoulder pain experienced while performing various activities are identified on a 10cm visual analog scale. Participants also had the option to select ‘item not performed’. 0 to 150: Higher scores indicate more pain.	Wheelchair-users45

ICF = International Classification of Functioning, Disability, and Health