Clark 1998 a

Methods	Participant blinding: not stated Therapist blinding: no Assessor blinding: not stated Analysis: available case Country: England Ethics approval: not stated
Participants	Number: 1st active [CT] ‐ 16; 2nd active [BSM] ‐ 17; control ‐ 15; total ‐ 48 (32 female; 16 male) Median age in years: total ‐ 34; inter‐quartile range 25‐43 Diagnostic criteria: hypochondriasis as assessed by SCID for DSM‐III‐R Recruited from: GPs (70%); medical specialists and psychiatrists (13%); clinical psychologists (13%) Median length of illness: total ‐ 4 years; inter‐quartile range 1‐10 years Exclusion criteria: 1. <30% belief they had a serious illness; 2. health worry not main problem; 3. age <18 or >60; 4. previous treatment with cognitive therapy or behavioural stress management; 5. depressive disorder requiring immediate psychiatric treatment; 6. physical illness which would account for health concerns; 7. psychotic disorder; 8. unwillingness to accept random allocation Language restrictions: English Comorbidity: not stated Number of drop‐outs: 1st active [CT] ‐ 1; 2nd active [BSM] ‐ 1 control ‐ 0; total ‐ 2
Interventions	Active treatment: 1. Cognitive Therapy; 2. Behavioural Stress Management Control treatment: waiting list Treatment setting: not stated (assumed to be secondary care outpatient) Discipline of therapists: psychologists Number and duration of sessions: 16 x 1 hour with up to 3 booster sessions Interval between sessions: 1 week Total exposure: 16 hours
Outcomes	Length of follow up: 12 months Primary outcome measure: none stated Secondary outcome measures: visual analogue scales: VAS ‐ time seriously worried about health VAS ‐ time free of health worries VAS ‐ avoidance of situations/events that might trigger health worries VAS ‐ checking parts of the body for signs of illness VAS ‐ need for reassurance VAS ‐ health worry related distress‐disability (patient rating) VAS ‐ health worry related distress‐disability (independent rating) Beck Anxiety Inventory Beck Depression Inventory Hamilton Anxiety Rating Scale Cognitions questionnaire ‐ frequency of thoughts about standardised set of illnesses Cognitions questionnaire ‐ belief in thoughts about standardised set of illnesses
Notes	unclear selection bias ‐ randomisation not described possible performance bias ‐ participants and therapists not blinded attrition bias unlikely possible detection bias ‐ assessor blinding status not stated Overall quality: moderate (QRS score = 26)
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear