Table 2. Instruments used in the online survey.

Concept	Instrument (abbreviation)
Health related Quality of Life	EQ-5D-5L [20, 42, 43]
Quality of care from the patient’s perspective	Patient Assessment of Chronic Illness Care (PACIC)–Short Form [23, 24]
Degree of control for individuals when decisions are being made regarding medical treatment	Computerized Control Preference Scale (eCPS) [21]
Impact of MS on day-to-day life	Multiple Sclerosis Impact Scale (MSIS-29) [22]
Disability and walking ability in Multiple Sclerosis	Patient Determined Disease Steps (PDDS) [25–27]
Social support	Brief Social Support Scale (BS6) [28]
Social participation	Short Scale Measuring Perceived Social Participation (KsT-5) [32]
	World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) [33, 44]
Self-efficacy	Generalized Self Efficacy scale (GSE) [29, 30]
Self-efficacy regarding use of the assistive devices	self-efficacy regarding assistive device use scale developed by Roelands et al. [41]
Reasons for non-use of an assistive device	Assistive Technology Device Predisposition Assessment (ATD PA) [38–40]
Evaluation of the assistive device delivery process	“Kwaliteit van Zorg” (KWAZO) [36, 37]
Satisfaction with the assistive device	Device subscale from the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0-G) [34, 35]

To check the comprehensibility and redundancy of the questionnaire, comprehensive cognitive pre-tests according to the concurrent think-aloud method were conducted [56]. The resulting revision of the questionnaire was likewise pretested. As an incentive for taking part in the survey, the DMSG Lower Saxony organises a day trip to a local zoo for 25 randomly chosen families of participating PwMS.