Williams 1996.

Methods	RCT; 3 arms; assessed at pre‐treatment, post‐treatment, 6 months, 1 year
Participants	End of treatment n = 99 Start of treatment n = 121 Sex: 68 F, 53 M Mean age = 50.0 (SD 11.5) Source = pain clinic Diagnosis = mixed chronic pain, low back commonest Mean years of pain = 7.8
Interventions	"inpatient CBT" "outpatient CBT" "waiting list"
Outcomes	Primary pain outcome: VAS pain Primary disability outcome: SIP patient‐rated Primary mood outcome: BDI depression Catastrophising outcome: CSQ catastrophising Visual analogue scale (VAS): pain intensity Visual analogue scale (VAS): pain distress Sickness Impact Profile (SIP): patient‐rated Beck Depression Inventory (BDI) State‐Trait Anxiety Inventory (STAI) Coping Strategies Questionnaire (CSQ): catastrophising Pain Self‐Efficacy Questionnaire (PSEQ) Pain Cognitions Questionnaire (PCQ)           Walk distance                     Arm endurance                       Stair climb                         Stand ups Medication use Health care use
Notes	CBT versus TAU, post‐treatment (waiting list not followed up): analyses 3.1, 3.2, 3.3 Yates quality scale: total quality = 22/35, design quality = 15/26, treatment quality = 7/9
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Randomly assigned by throw of a die”
Allocation concealment (selection bias)	High risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition reported
Selective reporting (reporting bias)	High risk	Partially reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	“interviewers and assistants blind to the patients’ treatment”