Table 2

Outcome criteria, measurement instrument, assessment points

Outcome/variableInstrumentAssessment point
T0 T1 T2*
Primary outcome
 Somatic symptom distressPHQ-15xxx
 Psychological and behavioural aspects of somatic symptom distressSSD-12xxx
Secondary outcome
 DepressionPHQ-9xxx
 AnxietyGAD-7xxx
 FunctioningPDIxxx
 Health anxietymSHAIxxx
 Attitude towards face-to-face psychotherapyATSPPHxxx
Covariates
 DemographicsWeb-based self-reportx
 Healthcare utilisationWeb-based self-reportxxx
 Somatosensory amplificationSSASx
 Emotional reactivityERSx
 Therapeutic allianceWAI-SR(x) †
 Attitudes and expectations towards iCBTCEQx
 Intervention satisfactionCSQ-Ix ‡x
 Subjective negative intervention effectsINEPx ‡x
 AdherenceAttrition/completion ratesx ‡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.