Table 1.

Descriptive, Primary, Secondary, Co-Variate, and Mechanism Variables.

Variable type	Domain	Measure (# items EMA, # items Extended)
Descriptive/Demographics	Patient Characteristics	Purpose built demographics, patient characteristics, and pain history questionnaire [[42], [43], [44], [45]]
Primary Outcome	Pain Interference	PROMIS Pain Interference (5, 5) [46,47]
Primary Mechanisms and Moderators	Cognitive Content	Pain Catastrophizing – Items from Pain Appraisal Scale (3, 5), Coping Strategy Questionnaire (2, Extended only) [48,49]
	Cognitive Process	Pain-Related Cognitive Process Questionnaire (PCPQ) Non-Judgment Scale (2, 6) [50]
	Activity Level	Actigraphy + Godin Leisure-Time Exercise Questionnaire (3, 3), hours spent sitting without exercising (EMA only) [51]
Secondary Outcomes	Average Pain Intensity	Numerical Rating Scale (NRS), 0–10 (1,1) [52]
	Mood	Positive and Negative Affect Schedule (PANAS) (2, 10) [53,54]
	Physical Function	PROMIS Physical Function (4, Extended only) [46,55]
	Sleep Quality	Actigraphy, PROMIS Sleep Disturbance (4, Extended only) [46,55]
	Depression	PROMIS Depression (4, Extended only) [46,55]
	Anxiety	PROMIS Anxiety (4, Extended only) [46,55]
	Medication Use	Purpose built Medication Use Questionnaire (Extended only)
	Medication Use Attitudes	Survey of Pain Attitudes (SOPA) Medication Beliefs Scale (6, Extended only) [56] and Pain Medication Questionnaire (PMQ) (26, Extended Baseline assessment only) [57]
	Post-Traumatic Stress Disorder	PTSD Checklist Civilian Version (PCL-C) (17, Extended only) [58]
Secondary Mechanisms	Pain Self-Efficacy	UW Pain-Related Self-Efficacy Scale (3, 6) [48]
	Patient Engagement	Clinician rated patient engagement (5, rated by clinician) [23]
	Therapeutic Alliance	Working Alliance Inventory (WAI) (12, EMA only) [59]
	Group Cohesion	Group Climate Questionnaire (GSQ-S) Engagement Scale (5, EMA only) [60]
	Skills Engagement	Purpose built duration and number of days/times practicing skills (EMA); number of days and duration of time practicing skills (Extended)
Tertiary Outcomes	Health Care Use	# visits to health care professional in last month (1, Extended only)
	Pleasurable Activity	Pleasant Events Schedule SF (10, Extended only) [61,62]
	Behavior Activation	Behavioral Activation for Depression Scale (BADS) (9, Extended only) [63]
	Quality of Life	Global quality of life (1, Extended only) [64]
	Employment Status	Employment question (1, Extended only)
	Weight Change	Weight question (1, Extended only)
	Patient Global Impressions of Change	Patient Global Impressions of Change (PGIC) (6, Extended post-treatment and follow-up assessment only); and Patient Global Assessment of Treatment Satisfaction (PGATS) (1, Extended post-treatment and follow-up assessment only)
Tertiary Mechanisms	Mindfulness	Mindful Attention Awareness Scale (MAAS) (15, Extended only) [65]
	Resilience	Pain Resilience Scale (14, Extended only) [66]
	Other Cognitive Processes	All other PCPQ items (47 additional, Extended only) [50]
	Pain Beliefs	Survey of Pain Attitudes (SOPA) Harm, Control and Disability Scales (18, Extended only) [56]
Exploratory Moderators	Cognitive Abilities	PROMIS Cognitive Function Abilities (6, Extended only) [46,55]
	Treatment Credibility	Treatment Credibility & Expectancies items [67] (5, EMA only)
	COVID-19	As of 2020: Investigator-developed items on COVID-19’s effects (6 items ext. & 1 item Qualitative Interview)
Covariate	Primary Problem (LBP primary or secondary)	Purpose built screening, self-report
Optional Assessments	Responses to Pain	Positive & Negative Response to Pain Scales (85, Extended Optional only) [68]
	Future Self	Future Self Questionnaire (FSQ) (16, Extended Optional only)
	Values-Consistent Goals	Valued Living Scale (VLS) [69] (8, Extended Optional only)
Qualitative Outcomes	Experiences in group & program feedback	15″–30″ of investigator-developed qualitative items