Table 2 Main results reported in included studies (n = 5)

Morales, 2020, Columbia

cross-over RCT [29]

Outcome measures (validated)

Reflux Disease Questionnaire Score, a 6-point score, with a higher score meaning a worse outcome and a change of ≥0.6 points considered clinically meaningful

Findings (improved)

Mean difference (MD) in change scores at 6 weeks of 1.327, 95% CI 0.626 to 2.027.

27 of 39 [69.2%] participants in the head-of-bed elevation group were more likely to report a clinically meaningful change of ≥10% in their symptom scores at 6 weeks compared to 13 [33.3%] in the control group. Risk ratio (RR) of 2.08; 95% CI 1.19 to 3.61).

NR

63.2% (95% CI 50.6 to 75.7%) of the 57 participants preferred the head of bed elevation to control.

39 of 63 participants in head-of-bed elevation group reported adverse events at 14 weeks compared to none on the control group (of 54): 20 bed slipping; 4 bed unsteadiness; 10 varicose vain pain; 7 musculoskeletal pain; and 1 sexual activity interference and headache each.

Huang, 2019, Taiwan,

cross-over RCT [28]

Outcome measures (validated)

Modified Dysfunction after Upper Gastrointestinal Surgery, a 30-point score, with higher scores means better outcomes.

Findings (improved)

MD in change scores at 2 weeks − 5.1, 95% CI − 7.6 to − 2.6

NR

NR

NR

Hamilton, 1988, United States, cross-over RCT [27]

NR

Outcome measures

Acid exposure, defined as percent of total time intra-oesophageal pH remained ≤4; Reflux episodes, defined as drop of intra-oesophageal pH to < 4; Acid clearance time, defined as the total time that intra-oesophageal pH < 4 by the number of reflux episodes.

Findings (improved)

A reduction in acid exposure in both sleeping on a wedge (mean% 14.8, 95% CI 12.2 to 17.5 vs control: 21.2, 95% CI 18.4 to 23.7) and head-of-bed elevation groups (mean% 15.3, 95% CI 11.7 to 18.8 vs control: 21.2, 95% CI 18.4 to 23.7) compared to the control. A non-statistically significant reduction in the number of reflux episodes and acid clearance time in any of the two groups compared to the control.

60% (9 of 15) preferred head-of-bed elevation, 33.3% (5 of 15) preferred sleeping on wedge, and 6.7% (1 of 15) preferred neither.

NR

Harvey, 1987, United Kingdom, factorial RCT [26]

Outcome measures

An overall improvement in symptoms and a 4-point-sclae of gastroesophageal reflux, retrosternal pain, epigastric pain, and dysphagia.

Findings (improved)

23 of 32 [71.9%] participants in the head-of-bed elevation group are more likely to report an overall improvement in symptoms at 6 weeks compared to 17 of 31 [54.8%] - unadjusted OR 2.1, 95% CI 0.74 to 5.99; adjusted OR 3.1, X² = 4, p < 0.005.

A statistically significant reduction in symptom scores of gastroesophageal reflux and retrosternal pain but not epigastric pain and dysphagia.

NR

NR

2 of 32 participants in the head-of-bed elevation group reported adverse events both resolved and neither discontinued: 1 bed slipping and 1 sexual activity interference.

Stanciu, 1977, United Kingdom, cross-over trial [25]

Outcome measures

Number of reflux symptoms (i.e. heartburn or acid regurgitation)

Findings (improved)

Compared to control group, a statistically significant reduction in the number of reflux symptoms during the intervention (6 h) in the head-of-bed elevation group (2.0 ± 1.2 vs. 3.0 ± 2.4) and sleeping on a wedge groups (2.4 ± 1.4 vs. 3.4 ± 2.2).

Outcome measures

Acid exposure, defined as percent of total time that intra-esophageal pH remained < 4; Reflux episodes, defined as a drop in intra-esophageal pH by 2; Acid clearance time, defined as the total duration of reflux by the number of reflux episodes.

Findings (improved)

A statistically significant reductions in acid exposure and reflux episodes in the head-of-bed elevation group (acid exposure: 6.7 ± 7.6; reflux episodes per participant: 3.7 ± 1.9) compared to control group (acid exposure: 14.0 ± 15.3; reflux episodes per participant: 6.2 ± 3.9) but no significant difference in sleeping on a wedge group compared to control group in terms of acid exposure (7.7 ± 11.7 vs 8.9 ± 9.7) and reflux episodes (5.4 ± 3.8 vs. 4.8 ± 3.2).

NR

NR