Burckhardt 1994.

Methods	Study setting: Europe (Sweden). Single‐centre, recruitment in occupational and primary health clinics, outpatient based Study design: Parallel Duration therapy: 6 weeks Follow‐up: 3 and 6 months Analysis: ANOVA (FIQ), MANOVA (QOLS‐S, FAI, SELF pain, SELF function, SELF other, 6‐min walk, chair test, myalgic score), if omnibus F significant ANOVA on individual outcomes, independent group t‐tests, paired different t‐tests for within group change
Participants	Patients: Treatment group: 28 patients; Control group: 30 patients; Total sample:100% female, 99% white, mean age 46.5 years; Duration of symptoms not reported Inclusion: ACR 1990 criteria for FM, normal results in laboratory tests (haemoglobin, free thyroxine, erythrocyte sedimentation rate, antinuclear antibodies, rheumatoid factor, creatine phosphokinase), understand Swedish Exclusion: Other rheumatic diseases
Interventions	Treatment Group: CBT, group: education, relaxation, assertiveness training, coping strategies, problem solving techniques (1x1.5h/week), total: 9h Control Group: Delayed treatment control Co‐medication allowed: Yes, not controlled for Other Co‐therapies: Not reported
Outcomes	Primary Outcomes Self reported pain: FIQ pain 0‐10; SD not reported and not provided on request; SDs calculated by imputation method Self reported negative mood: FIQ depression 0‐10; SD not reported and not provided on request; SDs calculated by imputation method Self reported disability: FIQ physical impairment 0‐10; SD not reported and not provided on request; SDs calculated by imputation method Acceptability: Total dropout rate Secondary Outcomes Self reported self efficacy pain: Self‐Efficacy (SES) pain scale 500‐50; SD not reported and calculated by reported P‐value Self reported fatigue: FIQ fatigue 0‐10; SD not reported and not provided on request; SDs calculated by imputation method Self reported sleep problems: Not assessed Self reported disease‐specific health‐related quality of life: FIQ total 0‐80; SD not reported and not provided on request; SDs calculated by imputation method
Notes	1. Study arm CBT plus physical therapy not used for comparison 2. Reasons for drop‐out ‐Total sample: 6x did not return for retesting (no separate data reported ‐Experimental groups: 7x did only attend 1 or 2 classes 3. Attendance rates: Not reported 4. Responder analysis: None 5. Funding sources and declaration of interest of the primary researchers: No details reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No detailed information
Allocation concealment (selection bias)	Unclear risk	No detailed information
Incomplete outcome data (attrition bias) All outcomes	High risk	No Intention‐to‐treat analysis
Selective reporting (reporting bias)	High risk	Except FIQ‐subscale scores all other outcomes not reported in detail at follow‐up and not provided on request
Blinding of outcome assessor	Unclear risk	No detailed information