Booker 2000.

Study characteristics
Methods	Study design: parallel‐group RCT
Participants	Country: USA Setting: multi‐center; medical and surgical ICU Inclusion criteria: receiving nutritional support through a gastric feeding tube with anticipated duration of tube feeding > 48 hours Exclusion criteria: not reported Baseline characteristics Number randomized: 35 Number analyzed: 18 Intervention arm Age (mean): 62.1 (range 18–77) years Number of participants: 10 Gender (men/women; n): 5/5 Control arm Age (mean): 58.9 (range 17–83) years Number of participants: 8 Gender (men/women; n): 4/4 Baseline imbalances: comparable
Interventions	Intervention arm All GRV discarded (frequency of monitoring: no data) Control arm All GRV returned (frequency of monitoring: no data) Loss to follow‐up: 17 participants withdrew from the trial: death (n = 2); transfer from ICU before completion of 3 days (n = 6); early removal of feeding tube (n = 5); missing data (n = 4). There was no mention of which arm these 17 participants belonged to. Duration of follow‐up: 3 days Duration of trial: September 1995 to June 1997
Outcomes	Volume aspirated from stomach
Notes	Funding source: Sigma Theta Tau, Delta Lambda Chapter, St Louis University Conflict of interest: unknown Clinical trial registration: unknown Duration of follow‐up was changed from 7 days due to serious numbers of missing data. Any disease severity scores of participants were not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	People who consented were assigned to treatment group randomly. Details of randomization methods not provided.
Allocation concealment (selection bias)	Unclear risk	Multi‐center (3 centers) study and often for such a study design, a centralized allocation method would be performed. However, for this study there were no further details on allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Unblinded.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Unblinded. For subjective outcomes, such as pneumonia and adverse events, the risk of detection bias would be high; for objective outcome measures, such as mortality, the risk of detection of bias would be low.
Incomplete outcome data (attrition bias) All outcomes	High risk	Data for 17 participants were omitted from analysis.
Selective reporting (reporting bias)	Low risk	All outcomes were reported.
Other bias	High risk	Lack of full‐time clinical research monitoring by study investigators.