Hogg 2004.

Study characteristics
Methods	Study design: double‐blind placebo‐controlled pilot study Number of study centres and location: single centre, UK Study setting: hospital inpatients Withdrawals: not stated Date of study: not stated
Participants	Number randomised: 24 Numbers in treatment group: not stated Number in placebo group: not stated Mean age: not stated Gender: not stated Diagnostic criteria: not stated Baseline lung function: not stated Inclusion criteria: known COPD patients presenting with an exacerbation Exclusion criteria: not stated
Interventions	Intervention: intravenous infusion of 1.2 g magnesium sulfate over 20 minutes Comparator: intravenous infusion of normal saline as placebo Concomitant medications: standard treatment
Outcomes	Modified Borg dyspnoea score, length of inpatient stay
Notes	Abstract only; full text not available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: only described as a randomised study, without details
Allocation concealment (selection bias)	Unclear risk	Comment: only described as a randomised study, without details
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: only described as a double‐blind study, without details
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: only described as a double‐blind study, without details
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: no details provided, no full‐text publication
Selective reporting (reporting bias)	Unclear risk	Comment: trial protocol was not accessible; unclear if all the outcomes were reported as planned.
Other bias	High risk	Comment: as there is no full‐text publication of this study, publication bias cannot be excluded