ACTRN12616000481471.

Trial name or title	Proton pump inhibitors vs histamine‐2 receptor blockers for ulcer prophylaxis therapy in the intensive care unit
Methods	Multi‐centre open‐label cluster‐randomised cross‐over study
Participants	Inclusion criteria Age ≥ 18 years Mechanically ventilated within 24 hours of ICU admission Exclusion criteria Admitted to ICU with upper GI bleeding (APACHE III admission diagnostic codes 303, 305, and 1403)
Interventions	Intervention: proton pump inhibitors Control: H2 receptor antagonists
Outcomes	Primary outcome All‐cause mortality in hospital Secondary outcomes Upper GI bleeding (new clinically significant upper GI bleeding developing as a complication in ICU) defined as overt GI bleeding (e.g. haematemesis, melena, or frank blood in the nasogastric tube or upper GI endoscopy) AND 1 or more of the following features within 24 hours of GI bleeding: Spontaneous drop of systolic mean arterial pressure or diastolic blood pressure of 20 mmHg or more Start of vasopressor or 20% increase in vasopressor dose Decrease in haemoglobin ≥ 20 g/L or Transfusion of 2 units of packed red blood Clostridium difficile infection rates defined as toxin‐positive or culture‐positive stool samples collected during an ICU admission (excluding any patients who had positive tests from specimens collected before ICU admission) Duration of mechanical ventilation Duration of ICU stay Duration of hospital stay
Starting date	April 2016
Contact information	Dr. Paul Young, Wellington Hospital, Riddiford Street, Newtown, Wellington 6021, New Zealand; paul.young@ccdhb.org.nz
Notes	anzctr.org.au/Trial/Registration/TrialReview.aspx?id=370438