Table 1.

Measurement instruments

Caregiver
Variable	Instrument/Source	No. of Items	Measurement	Type of Variable
Self-rated mental health	Mental Component Summary (MCS) of the General Health Survey Questionnaire Short Form 12 (SF-12) [4, 33]	6	T0 – T1	Primary outcome
Self-rated physical health	Physical Component Summary (PCS) of the General Health Survey Questionnaire Short Form 12 (SF-12) [4, 33]	6	T0 – T1	Secondary outcome
Social support	Perceived Social Support Caregiving (PSSC) [35]	9	T0 – T1	Secondary outcome
Social conflict	Perceived Social Conflict Scale (SCS) [35]	3		Control variable
Caregiver reaction	Caregiver Reaction Scale (CRS) [38–40]	24	T0 – T1	Secondary outcome
Education level	Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) [46]	2	T0	Control variable
Demographic variables	Single items	16	T0 – T1	Control variables
Care Recipient
Variable	Instrument/Source	No. of Items	Measurement	Type of Variable
Cognition	General Practitioner Assessment of Cognition (GPCOG) [42, 43]	6	T0 – T1	Control variable
Activities of daily Living	Functional Activities Questionnaire [44, 45]	10	T0 – T1	Control variable
Challenging behavior	Neuropsychiatric Inventory – Q [41]	12	T0 – T1	Secondary outcome
Demographic variables	Single items, e.g., age, gender, care dependency (care recipient)	22	T0 – T1	Control variables
Process Evaluation
Variable	Instrument (Source)	Measurement		Process Evaluation Domain
Recruitment strategies	Process documents of the TALKING TME study	T0		Reach
Numbers of interested, refused, rejected, and included informal caregivers	Process documents of the TALKING TIME study Single items (T0) and process documents of the TALKING TIME study	Ongoing1
Randomization	Process documents of the TALKING TIME study	Ongoing
Dropouts	Process documents of the TALKING TIME study	Ongoing
Participant responsiveness	Single items, e.g., quality/satisfaction with the support group content, the group, and its process	T1		Fidelity
Quality of delivery	Standardized support group protocols from the support group moderator and single items (T1), e.g., quality of the moderator, information booklet, telephone-based preliminary talk	Ongoing
Adherence	Standardized support group protocols from the support group moderator and single items (T1), e.g., deviations from the intervention protocol, usage of the information booklet	Ongoing		Dosage
Dose	Standardized support group protocols from the support group moderator, e.g., participation of the informal caregivers in the support group calls	T1
Socio-demographic characteristics of the participants and care recipients	Single items, e.g., age, gender, care dependency (care recipient)	T0 – T1		Context
Use of health care services	Use of service checklist [49]	T0 – T1

¹ Ongoing collection after each TALKING TIME support group meeting