Outcome criteria, measurement instrument, assessment points
Outcome/variable | Instrument | Assessment point | ||
T0 | T1 | T2* | ||
Primary outcome | ||||
Somatic symptom distress | PHQ-15 | x | x | x |
Psychological and behavioural aspects of somatic symptom distress | SSD-12 | x | x | x |
Secondary outcome | ||||
Depression | PHQ-9 | x | x | x |
Anxiety | GAD-7 | x | x | x |
Functioning | PDI | x | x | x |
Health anxiety | mSHAI | x | x | x |
Attitude towards face-to-face psychotherapy | ATSPPH | x | x | x |
Covariates | ||||
Demographics | Web-based self-report | x | ||
Healthcare utilisation | Web-based self-report | x | x | x |
Somatosensory amplification | SSAS | x | ||
Emotional reactivity | ERS | x | ||
Therapeutic alliance | WAI-SR | (x) † | ||
Attitudes and expectations towards iCBT | CEQ | x | ||
Intervention satisfaction | CSQ-I | x ‡ | x | |
Subjective negative intervention effects | INEP | x ‡ | x | |
Adherence | Attrition/completion rates | x ‡ | x |
*Only for control group.
†3 weeks after intervention start.
‡Only for intervention group.
T0, baseline; T1, 8 weeks postrandomisation; T2, 16 weeks postrandomisation; ATSPPH, Attitudes Towards Seeking Professional Psychological Help; GAD-7, Generalised Anxiety Disorder Questionnaire; INEP, Side Effects of Psychotherapy Inventory; mSHAI, modified short version of the Health Anxiety Inventory; PERS, Perth Emotion Reactivity Scale; PDI, Pain Disability Index; PHQ, Patient Health Questionnaire; SSAS, Somatosensory Amplification Scale; SSD-12, somatic symptom disorder—B Criteria Scale; WAI-SR, Working Alliance Inventory—short revised; CEQ, Credibility/Expectancy Questionnaire; CSQ-I, Client Satisfaction Questionnaire for internet-based interventions.