Table 2.

Regression coefficients of univariate moderator analyses.

Baseline variable	Treatment-covariate interaction
	$\widehat{\beta }$	$\sqrt{{\widehat{V}}_{\beta }}$	t	p(<|t|)	${\widehat{\mathrm{\tau }}}_{\text{Intercept}}^2$	${\widehat{\mathrm{\tau }}}_{\text{Slope}}^2$
Socio-demographics
Age	0.050	0.453	0.110	0.913	2.233	0.601
Gender, female	−0.665	0.915	−0.727	0.467	2.238	0.597
Relationship, yes	−0.886	0.875	−1.012	0.312	2.220	0.612
Education, >13 years	−0.544	0.921	−0.591	0.555	2.286	0.632
Children, yes	−0.661	0.890	−0.743	0.458	2.225	0.593
Lifetime SCID diagnosis, yes	−0.737	1.484	−0.497	0.619	1.019	0.905
Previous psychotherapy, yes	0.031	0.925	0.034	0.973	2.164	0.610
Previous depression medication, yes	0.503	0.927	0.543	0.587	2.191	0.646
Previous back pain medication, yes	−1.945	0.886	−2.194	0.028	2.206	0.612
Sick leave, yes	−1.320	1.007	−1.311	0.191	2.056	0.555
Social support, (very) good	1.012	0.889	1.139	0.255	2.134	0.586
Internet affinity (IAS)	−0.006	0.458	−0.013	0.990	2.164	0.596
Recruitment, online	1.028	0.891	1.155	0.248	2.304	0.636
Symptom severity
Depressive symptom severity (PHQ-9)	−0.763	0.413	−1.847	0.065	0.444	0.348
Depressive symptom severity (HAM-D-17)	−0.752	0.480	−1.568	0.117	0.359	0.491
Pain intensity (NRS)	−0.423	0.444	−0.952	0.341	1.941	0.616
Quality of life (AQoL-6D)	−0.477	0.430	−1.108	0.268	0.390	0.557
Pain-related risk factors
Pain self-efficacy (PSEQ)	0.072	0.438	0.164	0.870	1.376	0.904
Subjective employment forecast (SPE)	−0.326	0.449	−0.726	0.468	1.925	0.559
Pain-related disability (ODI)	−0.256	0.429	−0.598	0.550	1.408	0.634

Note. A Wishart prior was used for the covariance-variance matrix of the random effects. AQoL-6D: Assessment of Quality of Life, HAM-D-17: Hamilton Depression Rating Scale, IAS: Internet Affinity Scale; NRS: numerical rating scale, ODI: Oswestry Disability Scale, PHQ-9: Patient Health Questionnaire, PSEQ: Pain self-efficacy questionnaire, SPE: Subjective Prognostic Employment Scale.