Table 2 Risk of bias in included studies
Study name | Random sequence generation | Allocation concealment | Blinding | Completeness of data | Selective outcome reporting | Other bias |
|---|---|---|---|---|---|---|
Faisy et al., 2016 [6] | Low risk “The randomization sequence was programmed in advance and generated by a statistician independent of the study” | Low risk “Patients were randomized via a computer-generated assignment sequence in a centralized blinded fashion” | Low risk “Double-blind placebo-controlled trial” No details provided on which specific groups were blinded | Low risk “One patient from each group was excluded” | Low risk All outcomes listed in the methods section are reported in the results section | High risk Means and standard deviations were extrapolated from medians and interquartile ranges |
Rialp Cervera et al., 2017 [8] | Low risk “Randomization was based on computer-generated random numbers” | Low risk “Treatment and placebo capsules were prepared, packaged and blinded in a centralized hospital pharmacy and distributed to all ICUs” | Low risk “Double-blind study” “Investigators, patients and caregivers were unaware of the randomization list” | Low risk “All enrolled patients completed the trial and were included in the final analysis” | Low risk All outcomes listed in the methods section are reported in the results section | Low risk |
Nelson and Wallace, 1965 [12] | Unclear risk Method of random sequence generation not specified | Unclear risk Method of allocation concealment not specified | Low risk “Active and placebo tablets were identical in appearance, and their identity was unknown to the patients and to the assessors during the trial” | High risk “Nineteen patients began the trial, but only 12 were included in the final analysis” | Low risk All outcomes listed in the methods section are reported in the results section | Low risk |
Haecki et al., 1983 [15] | Unclear risk Method of random sequence generation not specified | Unclear risk Method of allocation concealment not specified | Low risk “Double blind trial” No details provided on which specific groups were blinded | Low risk “One patient refused follow-up” | Low risk All outcomes listed in the methods section are reported in the results section | Low risk |
Vos et al., 1994 [29] | Unclear risk Method of random sequence generation not specified | Unclear risk Method of allocation concealment not specified | Low risk of bias “Double blind trial” No details provided on which specific groups were blinded | Low risk “All patients were studied during three nights” | Low risk All outcomes listed in the methods section are reported in the results section | Low risk |
Gulsvik et al., 2013 [28] | Low risk “Randomization was based on computer-generated random numbers” | Low risk “Patients were allocated randomly on a 1:1 basis to a sealed and numbered box containing either acetazolamide or placebo tablets with similar size and colour” | Low risk “placebo controlled and double-blind parallel group trial” | Low risk All enrolled patients were included in the final analysis | Low risk All outcomes listed in the methods section are reported in the results section | Low risk |