Table 1

Key variables and measurements

VariablesMeasurementDepression screenings (PHQ-9)T0T1T2
123
Inclusion/exclusion criteria
 Chronic back painMR+TIxx
 Mild-to-moderate depression or dysthymiaPHQ-9/HAM-D/QIDS/SCIDxxx
 Severe depression (ICD-10 F32.2/F32.3/F33.2/F33.3 diagnosis)SCIDxxx
 SuicidalityHAM-D/QIDS/SCIDxxx
PHQ-9xxxxxx
 Further inclusion and exclusion criteria 1, 4, 5 and 6SRQ+TIxx
Primary outcome
 Depression severityHAM-Dxxx
Secondary outcomes
 Depression remission and responseHAM-D/SCID/QIDSxxx
 Quality of lifeAQol-6D/EQ-5D-5Lxxx
 Pain intensityNumerical rating scalexxx
 Pain-related disabilityODIxxx
 Pain self-efficacyPSEQxxx
 Work capacitySPExxx
Measurements for the economic evaluation
 CostsTiC-Pxx
 Quality of lifeAQol-6D/EQ-5D-5Lxxx
Covariates
 Demographic variablesSRQ/MRxx
 Depression type and chronicitySCIDxxx
 Prior depression treatmentTIxx
 Back pain type and chronicityMRxx
 Internet affinityIASxx
 Patient adherence*Attrition ratexx
 Patient satisfaction*CSQ-8x
 Negative effects of the interventionINEP/SRQ/TI/SReCx
  • *Intervention group only.

  • AQol-6D, Assessment of Quality of Life; CSQ-8, Client Satisfaction Questionnaire; EQ-5D-5L, European Quality of Life scale; HAM-D, Hamilton Rating Scale for Depression; IAS, Internet Affinity Scale; ICD-10, 10th revision of the International Statistical Classification of Diseases and Related Health Problems; INEP, Inventory for the Assessment of Negative Effects of Psychotherapy; MR, medical record; ODI, Oswestry Disability Index; PHQ-9, Patient Health Questionnaire-9; PSEQ, Pain Self-Efficacy Questionnaire; QIDS, Quick Inventory of Depressive Symptomatology; SCID, Structured Clinical Interview; SPE, Subjective Prognostic Employment Scale; SReC, self-report during treatment to the eCoach; SRQ, Self-Report Assessment Questionnaire, TI, telephone interview; TiC-P, Trimbos/iMTA questionnaire for costs associated with psychiatric illness.