Aronstam 1977.

Study characteristics
Methods	Single‐centre RCT. Cross‐over trial. Trial conducted over 2 school terms. Note: there are 3 school terms per annum in the UK.
Participants	Country: England. Participants: males with haemophilia A (factor VIII < 1%). Age range: 13 ‐ 17 years. Number enrolled: 4 All participants completed the trial. Those boys who had been on the first double‐blind controlled trial (Aronstam 1976) and were still available for a further 2 terms were selected. There were 4 such boys, patients 1, 3, 8, and 9 of that trial. The boys selected had each had at least one full school term off prophylaxis before entering the second trial.
Interventions	Cryoprecipitate (prepared by Wessex Regional Transfusion Centre) or Kryobulin (prepared by Serological Products, UK). Type of prophylaxis: 2 prophylaxis arms; Arm A: raise factor VIII to 15% twice weekly. Arm B: raise factor VIII to 30% twice weekly. Follow‐up duration: 2 school terms
Outcomes	Bleeding events or frequency.
Notes	Source of funding: Sir William Coxon Trust and the Lord Mayor Treloar Trust.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	While authors indicated that random sequence generation was used to allocate participants to groups, no details were given.
Allocation concealment (selection bias)	Unclear risk	No details on allocation concealment were given.
Blinding (performance bias and detection bias) Clinical Joint Function	Unclear risk	Not assessed.
Blinding (performance bias and detection bias) Bleeding	Low risk	Participants and personnel were unaware of allocation.
Blinding (performance bias and detection bias) Radiologic Joint Score	Unclear risk	Not assessed.
Blinding of outcome assessment (detection bias) Bleeding	Low risk	Outcome assessors were blinded to allocation.
Blinding of outcome assessment (detection bias) Clinical Joint Function	Unclear risk	Not assessed.
Blinding of outcome assessment (detection bias) Radiologic Joint Score	Unclear risk	Not assessed.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data are present for all participants.
Selective reporting (reporting bias)	Low risk	While the trial protocol was not available, all expected outcomes were reported for all participants.
Other bias	Unclear risk	Washout period between arms is unclear.