Martin 1980.

Methods	Quasi‐randomised trial
Participants	Baseline characteristics Number randomised: 77 participants Number analysed: 77 participants Antacids Age (years; mean (SD)): 30.5 (15.3) Number of participants (n): 37 Gender (male/female; n): 32/5 Cimetidine Age (years; mean (SD)): 29.9 (14) Number of participants (n): 40 Gender (male/female; n): 30/10 Inclusion criteria Admitted to Louisville General Hospital surgical intensive care unit Admitted for at least 3 days in ICU Requiring gastric drainage by nasogastric or gastrostomy tube Exclusion criteria GI haemorrhage at the time of admission Baseline imbalances: no difference between antacid and cimetidine groups in age and gender. The main reasons for admission were head injury and orthopaedic injury
Interventions	Antacids Dose (total/d): 1440 mL Duration of treatment (days): until discharged from intensive care or after initiation of feedings Route: NG or gastrostomy tube Intervention: given as an hourly dose of 60 mL (Gelusil, Warner/Chilcott, Morris Plains, NJ with buffering capacity of 1.3 m Eq/mL) through the Ng or gastrostomy tube followed by a 10‐mL flush of tap water, then connected to low continuous suction for 30 minutes. The sequence was repeated every hour provided the gastric pH was 4 or greater. If gastric pH was less than 4 on any 3 of 6 consecutive hourly measurements, it was increased to 90 mL/h. If the pH was still less than 4, dose was increased to 120 mL/h and cimetidine was added at a dose of 300 mg IV every 4 hours. It was increased to 300 mg every 3 hours if pH of less than 4 persisted Concomitant medications: hydrochloride (ranitidine), continuous infusion at 0.25 mg/kg/h, after a loading dose of 0.5 mg/kg combined with antacids (30 to 60 mL PRN via NG tube for persistent pH < 4) Cimetidine Dose (total/d): 1800 mg Duration of treatment (days): until discharged from intensive care or after initiation of feedings Route: IV Intervention: 300 mg IV every 4 hours (if gastric pH was less than 4 on any 3 of 6 consecutive hourly aspirations, the rate of administration of the drug was increased to every 3 hours. If the pH was still not maintained, then Gelusil was added at 60 mL/h through NG or gastrostomy tube followed by a 10‐mL flush of tap water, and the tube was clamped 30 of every 60 minutes. The dose of antacids was progressively raised according to protocol while the dose of cimetidine was maintained at 300 mg IV every 3 hours (if renal failure was diagnosed, cimetidine was administered at 300 mg every 12 hours) Concomitant medications: ‐ Adherence to regimen: 49 participants in both groups maintained a gastric pH ≥ 4 (29 in antacid and 20 in cimetidine). Fifteen participants required increase in dosage, as they were not able to maintain a gastric pH ≥ 4 at the initial dose (6 in antacid and 7 in cimetidine). For 4 participants who were on cimetidine, an additional antacid administration was required. Nine participants failed to maintain a pH ≥ 4 despite maximum dose as per the study protocol (2 in antacid and 7 in cimetidine) Duration of trial: January 1979 to August 1979 Duration of follow‐up: Quote: "Patients were observed throughout their hospitalisation for GI bleeding and if it developed they were readmitted to the study and to intensive care unit"
Outcomes	Outcomes sought in review and reported in trial Incidence of GI bleeding defined as Gastric aspirate that was 3+/4 positive (or grossly bloody) on 3 of 4 consecutive hourly examinations Red blood that was returned through the nasogastric or gastrostomy tube that did not immediately clear with 500 mL lavage of normal saline solution Melena that developed after initiation of therapy All‐cause mortality in ICU Participants requiring blood transfusion Adverse events of interventions (nil) Incidence of pneumonia (unintended reporting) Outcomes sought but not reported in trial Duration of intubation Duration of ICU stay All‐cause mortality in hospital Units of blood transfused Outcomes reported in trial but not used in review Gastric pH values
Notes	Setting: Louisville General Hospital surgical intensive care unit Source of funding: ‐ Conflicts of interest: ‐ Ethics approval: ‐ Informed consent: ‐ Clinical trials registration: ‐ Sample size calculation: ‐ Additional notes: It is mentioned that 19 participants had pneumonia (7 in antacid and 12 in cimetidine), but it was not an outcome intended to be reported in the study. Not sure if this was present on admission
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote: "patients were assigned to either antacid or cimetidine treatment group according to odd or even date of admission"   Comment: This was a quasi‐randomised trial, so sequence generation was not done
Allocation concealment (selection bias)	High risk	Quote: "patients were assigned to either antacid or cimetidine treatment group according to odd or even date of admission"   Comment: This was a quasi‐randomised trial in which allocation was not concealed
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: This was not a placebo‐controlled trial, and the different modes of administering study interventions would not have made it possible to blind study personnel and participants. Therefore, high risk of performance bias
Blinding (detection bias) Clinically important upper GI bleeding	Low risk	Comment: Blinding was not done ,and GI bleeding was an objective outcome that was detected as per the definition in the study objectives
Blinding (detection bias) Nosocomial pneumonia	Unclear risk	Comment: Blinding was not done, and there was no intention to report pneumonia in the study objectives. It was reported when it was diagnosed in participants and was the main cause of sepsis in participants. Unclear whether pneumonia was present on admission
Blinding of outcome assessment (detection bias) Adverse reactions of interventions	Low risk	Comment: All other outcomes of interest were objective in nature; because of this, the likelihood of detection bias is low
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: All participants were included in the final analysis. There was no attrition bias
Selective reporting (reporting bias)	Low risk	Comment: All intended outcomes were analysed and reported. Pneumonia was reported although it was not intended. However this was an outcome of interest for the review. Therefore it could have caused reporting bias
Other bias	Low risk	Comment: Source of funding is unclear from the study report. No other sources of bias are suspected