Skorodin 1995.

Study characteristics
Methods	Study design: double‐blind randomised controlled trial Number of study centres and location: 2; Edward Hines Jr. Veterans Affairs Hospital, Hines, Illinois and Augusta (GA) Veterans Affairs Medical Center Study setting: emergency department (ED) Withdrawals: not stated Date of study: not stated
Participants	Number randomised: 72 Numbers in treatment group: 36 Number in placebo group: 36 Mean age (years): 62.8 (SD 9.0) (magnesium); 66.5 (SD 7.3) (placebo) Gender (male/female): 35/1 (magnesium); 35/1 (placebo) Diagnostic criteria: ATS Mean duration of COPD (years): 11 (SD 10.6) (magnesium); 11 (SD 13) (placebo) Baseline lung function: Mean PEFR at presentation (L/min): 122.8 (magnesium); 119.7 (placebo) Smoking history: Mean duration of smoking (years): 39.7 (magnesium); 39.5 (placebo) Serum magnesium level (mmol/L) mean: 0.94 (SD 0.16) (magnesium); 0.98 (SD 0.16) (placebo) Inclusion criteria: people aged 35 years or older who presented with acute exacerbation of COPD Exclusion criteria: temperature > 37.9º C; systolic blood pressure < 100 mmHg; history of kidney disease; clinical evidence of pneumonia; initial PEFR > 250 L/min.
Interventions	Intervention: IV 1.2 g of magnesium sulfate in 150 mL of normal saline over 20 minutes Comparator: IV 2.5 mL of saline in 150 mL of normal saline over 20 minutes as placebo Concomitant medications: nebulised albuterol 2.5 mg in 3 mL of normal saline; supplemental oxygen 2L/min via nasal cannula if SpO2 less than 88%; standard treatment.
Outcomes	Dyspnoea score, PEFR, hospital admission, emergency department visit in next two weeks, MIP and MEP
Notes	Funding for studies: Veterans Affair Health Services Research & Development grant 90‐091; magnesium sulfate was donated by Abbot Lab Conflicts of interest of trial authors: not declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: stated as "coded from a randomised list", with no elaboration on how sequence generation was performed.
Allocation concealment (selection bias)	Low risk	Quote: "placebo and magnesium sulfate solutions were prepackaged and coded from a randomised list"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "randomised in a double‐blind fashion" Quote: "placebo and magnesium sulfate solutions were prepackaged in identical vials in the pharmacy and added to the normal saline in the pharmacy before delivery to the emergency department"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: no details provided for outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: there were no dropouts from the study arms.
Selective reporting (reporting bias)	Unclear risk	Comment: unclear if all outcomes were reported as planned since trial protocol was not available.
Other bias	Low risk	Comment: no other apparent biases identified.