Christensen 1985.

Methods	Randomised clinical trial.
Participants	Country: multicentric; international. Number randomised: 248. Post‐randomisation dropouts: 63 (25.4%). Revised sample size: 185. Mean age: 55 years. Females: not stated. Symptomatic participants: not stated. AMA positive: not stated. Mean follow‐up period (for all groups): minimum 63 months. Inclusion criteria Symptom status: not stated. AMA status: AMA‐positive and AMA‐negative participants. Response status: not stated. Exclusion criteria No antimetabolites in the previous 6 months.
Interventions	Participants were randomly assigned to 2 groups. Group 1: azathioprine (n = 98). Further details: azathioprine: escalating doses up to a maximum of 100 mg/day; duration: not stated. Group 2: placebo (n = 87).
Outcomes	Mortality.
Notes	Reasons for post‐randomisation dropouts: lost to follow‐up.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: information not available.
Allocation concealment (selection bias)	Unclear risk	Quote: "Patients were randomized to azathioprine or placebo separately for each centre and for each sex by the sealed envelope technique". Comment: further details of sealed envelope technique were not available.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Comment: identical placebo used and authors stated double‐blind.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: identical placebo used and authors stated double‐blind.
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: there were post‐randomisation dropouts.
Selective reporting (reporting bias)	High risk	Comment: adverse events not reported.
For‐profit bias	High risk	Quote: "This work was also supported by the Wellcome Foundation. J.N. was supported by Ciba‐Geigy Ltd".
Other bias	Low risk	Comment: no other source of bias.