No.

Query

#23

#20 AND #21 AND [1‐1‐2012]/sd NOT [21‐5‐2020]/sd

#22

#20 AND #21

#21

[embase]/lim NOT [medline]/lim

#20

#16 AND #19

#19

#17 OR #18

#18

random*:ti,ab OR placebo*:ti,ab OR factorial*:ti,ab OR crossover*:ti,ab OR assign*:ti,ab OR allocat*:ti,ab OR volunteer*:ti,ab OR 'double blind':ti,ab OR 'double blinding':ti,ab OR 'double blinded':ti,ab OR 'single blind':ti,ab OR 'single blinded':ti,ab OR 'single blinding':ti,ab

#17

'crossover procedure'/exp OR 'single blind procedure'/exp OR 'randomized controlled trial'/exp OR 'controlled clinical trial'/exp

#16

#14 AND #15

#15

'antibiotic prophylaxis'/exp OR 'antibiotic agent'/exp OR antibiotic*:ti,ab

#14

#12 OR #13

#13

'ventilator associated pneumonia'/exp OR 'ventilator associated pneumonia':ti,ab

#12

#6 AND #11

#11

#7 OR #8 OR #9 OR #10

#10

'artificial ventilation'/exp OR respirator*:ti,ab

#9

'ventilator'/exp OR ventilator*:ti,ab

#8

'critical illness'/exp OR 'critically ill':ti,ab OR 'critical illness':ti,ab

#7

'intensive care unit'/exp OR icu:ti,ab OR 'critical care':ti,ab OR 'intensive care':ti,ab OR 'burn unit':ti,ab OR 'burn units':ti,ab OR 'care unit':ti,ab OR 'care units':ti,ab OR 'recovery room':ti,ab OR 'recovery rooms':ti,ab

#6

#1 OR #2 OR #3 OR #4 OR #5

#5

'tracheitis'/exp OR tracheit*:ti,ab

#4

bronchit*:ti,ab OR bronchiolit*:ti,ab OR pharyngit*:ti,ab

#3

pneumon*:ti,ab OR hap:ti,ab OR vap:ti,ab OR bronchopneumonia*:ti,ab OR pleuropneumonia*:ti,ab

#2

'respiratory tract infection':ti,ab OR 'respiratory tract infections':ti,ab

#1

'respiratory tract infection'/exp OR 'bronchitis'/exp OR 'pharyngitis'/exp OR 'pneumonia'/exp

Random sequence generation (selection bias)

Low risk

The investigators describe a random component in the sequence generation process such as: random number table; computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots; minimisation.

High risk

The investigators describe a non‐random component in the sequence generation process such as: odd or even date of birth; date (or day) of admission; hospital or clinic record number; alternation; judgement of the clinician; results of a laboratory test or a series of tests; availability of the intervention.

Unclear risk

Insufficient information about the sequence generation process to permit judgement of low or high risk

Allocation concealment (selection bias)

Low risk

Investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web‐based, and pharmacy‐controlled randomisation); sequentially numbered drug containers of identical appearance; sequentially numbered, opaque, sealed envelopes.

High risk

Investigators enrolling participants could possibly have foreseen assignments because one of the following methods was used: open random allocation schedule (e.g. a list of random numbers); assignment envelopes without appropriate safeguards (e.g. if envelopes were unsealed or non­opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.

Unclear risk

Insufficient information to permit a judgement of low or high risk. This is usually the case if the method of concealment is not described or not described in sufficient detail to permit a definitive judgement.

Blinding of participants and providers (performance bias)

Low risk

No blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding.

Blinding of participants and key study personnel ensured, and it is unlikely that the blinding could have been broken.

High risk

No blinding or incomplete blinding, and the outcome is likely to be influenced by lack of blinding.

Blinding of key study participants and personnel was attempted, but it is likely that the blinding could have been broken, and the outcome is likely to be influenced by lack of blinding.

Unclear risk

Insufficient information to permit a judgement of low or high risk

Blinding of outcome assessor (detection bias)

Low risk

No blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding.

Blinding of outcome assessment is ensured, and it is unlikely that the blinding could have been broken.

High risk

No blinding of outcome assessment, and the outcome measurement is likely to be influenced by lack of blinding.

Blinding of outcome assessment, but it is likely that the blinding could have been broken, and the outcome measurement is likely to be influenced by lack of blinding.

Unclear risk

Insufficient information to permit a judgement of low or high risk

Incomplete outcome data (attrition bias)

Low risk

No missing outcome data.

Reasons for missing outcome data are unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).

Missing outcome data are balanced in numbers across intervention groups, with similar reasons for missing data across groups.

For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk is not enough to have a clinically relevant impact on the intervention effect estimate.

For continuous outcome data, plausible effect size (difference in means or standardised difference in means) amongst missing outcomes is not enough to have a clinically relevant impact on observed effect size.

Missing data have been imputed using appropriate methods.

All randomised participants are reported/analysed in the group to which they were allocated by randomisation irrespective of non‐compliance and co‐interventions (intention‐to‐treat).

High risk

Reason for missing outcome data is likely to be related to true outcome, with either an imbalance in numbers or reasons for missing data across intervention groups.

For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk is enough to induce clinically relevant bias in intervention effect estimate.

For continuous outcome data, plausible effect size (difference in means or standardised difference in means) amongst missing outcomes is enough to induce clinically relevant bias in observed effect size.

‘As‐treated’ analysis done with substantial departure of the intervention received from that assigned at randomisation.

Unclear risk

Insufficient information to permit a judgement of low or high risk (e.g. number randomised not stated, no reasons for missing data provided; number of dropouts not reported for each group)

Selective reporting (reporting bias)

Low risk

The study protocol is available, and all of the study’s prespecified (primary and secondary) outcomes that are of interest in the review have been reported in the prespecified way.

The study protocol is not available, but it is clear that the published reports include all expected outcomes, including those that were prespecified (convincing text of this nature may be uncommon).

High risk

Not all of the study’s prespecified primary outcomes have been reported.

One or more primary outcomes are reported using measurements, analysis methods, or subsets of the data (e.g. subscales) that were not prespecified.

One or more reported primary outcomes were not prespecified (unless clear justification for their reporting is provided, such as an unexpected adverse effect).

One or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta‐analysis.

The study report fails to include results for a key outcome that would be expected to have been reported for such a study.

Unclear risk

Insufficient information to permit a judgement of low or high risk