Moradi 2021.

Study characteristics
Methods	Study design: randomised double‐blind placebo‐controlled trial Number of study centres and location: single centre; Emam Reza hospital in north‐east of Iran, affiliated with Mashhad University of Medical Sciences Study setting: emergency department (ED) Withdrawals: stated Date of study: October 2017 to March 2018
Participants	Number screened: 167 Number randomised: 77 Number in treatment group: 39 Number in placebo group: 38 Mean age (years): 71.9 (SD 7) (magnesium); 69.8 (SD 8.2) (placebo) Gender (male/female): 20/19 (magnesium); 22/16 (placebo) Diagnostic criteria: physician diagnosed Baseline lung function: Mean PEFR at presentation (% of predicted): 27.3 (magnesium); 28.1 (placebo) Smoking history Current smokers: 5 (magnesium); 7 (placebo) Ex smokers: 19 (magnesium); 20 (placebo) Non‐smokers: 15 (magnesium); 11 (placebo) Inclusion criteria: adults with the initial diagnosis of AECOPD Exclusion criteria: people who: need immediate endotracheal intubation or mechanical ventilation; were haemodynamically unstable; were uncooperative or unable to perform peak flow meter; were pregnant; had other conditions or complications contributing to dyspnoea, such as pneumonia, pleural or pericardial effusion, pneumothorax, heart failure, renal failure, sepsis, or a past history suggestive of asthma.
Interventions	Intervention: intravenous infusion of 2.5 g of MgSO4 (5 mL of 50% solution) in 50 mL of normal saline over 15 minutes Comparator: intravenous infusion of 5 mL sterile water in 50 mL of normal saline over 15 minutes as placebo Concomitant medications: standard treatment with supplemental oxygen to maintain SpO2 > 90%, nebulized salbutamol, nebulized ipratropium, IV hydrocortisone, IV ceftriaxone and oral azithromycin
Outcomes	Primary outcomes changes in PEFR DSS RR Secondary outcomes need for endotracheal intubation after randomisation ED discharge rate
Notes	Funding for studies: Mashhad University of Medical Sciences Conflicts of interest of trial authors: declared none Clinical Trials Registry: IRCT2014111519962N1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomisation was performed by block randomisation (blocks of 4) by a third party."
Allocation concealment (selection bias)	Low risk	Quote: "patients were randomly allocated to either group A (MgSO4) or group B (placebo) by a third party process so that patients and researchers were unaware of allocation."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Patients, treating physician, and investigators were blinded to the treatment. A nurse who was not involved in patients’ care prepared the MgSO4/placebo vials by filling similarly appearing vials with 5 mL of MgSO4 (50% solution) or sterile water daily and kept the codes for content of each bottle in a log not accessible by the investigators until the completion of the study"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: "Participant, care provider, investigator and outcome assessor" were masked.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comments: 4 participants lost to follow‐up (5.2 %), reasons not provided.
Selective reporting (reporting bias)	Low risk	Comment: trial was registered on website, all outcomes were reported as planned.
Other bias	Low risk	Comment: no other apparent biases identified.