Bathon 2000 (ERA).

Methods	Method of randomisation not reported Allocation concealment not reported Blinding not reported, but treatments provided in identical containers Multicentre parallel group study Power calculation not reported No of participants randomised = 632 No of participants analysed = 632 Intention‐to‐treat analysis Source of funding: Immunex (pharmaceutical company)
Participants	Inclusion: At least 18 years; RA max 3 years; no other illnesses; no treatment with MTX; at high risk for radiographic progression No exclusion criteria reported Location: centres in the USA
Interventions	Etanercept 10 mg SC twice weekly Etanercept 25 mg SC twice weekly MTX (initially 7.5 mg increasing to 20 mg at week 8) (PBO controlled) Duration: 12 months
Outcomes	ACR20, ACR50, ACR70 Radiographic: TSS, Erosion Score, Joint Space Narrowing Score; withdrawals; adverse events
Notes	Early RA; MTX naive; most erosions and RF+
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not described
Allocation concealment (selection bias)	Unclear risk	Method not described
Blinding (performance bias and detection bias) Clinical outcomes	Low risk	Not explicitly described but PBO controlled; assessors of radiographic scores unaware of assignment
Incomplete outcome data (attrition bias) Clinical outcomes	Low risk	Analyses were intention to treat: inclusion of all participants who received at least 1 dose of the study drug
Selective reporting (reporting bias)	Low risk	No evidence of a prior published protocol but wide range of outcomes assessed
Other bias	Unclear risk	Drug company funding with no guarantees described to ensure that the results were not influenced