Burton 1978.

Methods	Randomised but not blind Intervention took place over 3 years, treatment maintained at starting doses until 'rash suppressed' at which point prednisone doses were gradually reduced in both groups. If rash did not recur then also azathioprine was gradually withdrawn in the azathioprine group Follow‐up: at the end of the 3‐year treatment period
Participants	25 participants with BP confirmed by IF studies
Interventions	A: 12/12 participants prednisone (30 to 80 mg/day) + azathioprine (2.5 mg/kg/day). B: 13/13 participants prednisone (30 to 80 mg/kg/day).
Outcomes	Unclear outcome measures: Whether azathioprine + prednisolone (synergistic immunosuppression) associated with increased risk of malignancy Disease control Cumulative dose of prednisone in both groups Mortality
Notes	After 1 week of prednisolone to suppress lesions, consultant decided whether to include in trial. Not clear how prednisolone dose decided or numbers of participants on lower or higher doses in each group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details given.
Allocation concealment (selection bias)	Unclear risk	Quote: "Once included, each participant was randomly assigned ......by the ward sister who drew a marked paper from an envelope." (Page 1190)
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Unclear. Unlikely as the intervention group (azathioprine) were monitored by frequent blood testing.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unclear. The results section states that 25 participants completed a 3‐year follow‐up, but it is unclear how many were randomised to each group at the start. Table 1 page 1190 reports outcomes over 3 years for all 25 participants.
Selective reporting (reporting bias)	Unclear risk	Outcome measures were not clearly stated.
Other bias	Unclear risk	Only those participants who were likely to attend for follow up were recruited. Elibility was also determined by the consultant doctor after baseline testing. Baseline imbalance: There were more participants with severe disease in the azathioprine group, 53% had ≥ 20% body surface area involvement compared to only 27% in the MMF group.