Hossein 2016.

Methods	Double blind, randomised controlled trial. 2 emergency departments, Iran.
Participants	Inclusion criteria: moderate/severe asthma exacerbation defined by PEFR < 40% to 69% predicted or limiting speech/normal activity, age > 16 years. Exclusion criteria: need for immediate intubation, significant impairment of heart function, kidney or liver disease, fever > 38.3 °C, chronic lung disease, pregnancy, lactation, pneumonia. 50 randomised. Intervention: 25 randomised. Mean age (years): 52.4 (16.9). Men:women: 11:14. Acute moderate: 3. Acute severe: 22. Mean predicted PEF (%): 15.1 (4.7). Control: 25 randomised. Mean age (years): 53.9 (16.2). Men:women: 14:11. Acute moderate: 3. Acute severe: 21 Mean predicted PEF (%): 14.7 (6.4).
Interventions	Intervention: 3 mL MgSO₄ solution (260 mmol/L) nebulised. Control: 3 mL 0.9% NaCl nebulised. Nebulised medication given every 20 to 60 minutes.
Outcomes	Predicted PEFR (%), oxygen saturations, respiratory rate, dyspnoea severity index (20, 60 minutes); need for admission, serious side‐effect rate (60 minutes). Adverse effects: no "serious side‐effects" reported.
Notes	Funding: not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation software used.
Allocation concealment (selection bias)	Unclear risk	Data not given.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Both patients and investigators were blinded to the content of identical treatment vials.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Both patients and investigators were blinded to the content of identical treatment vials.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The report does not state that all 25 randomised participants in each arm completed the trial, but as the trial finished at 60 mins is it likely that they did.
Selective reporting (reporting bias)	Unclear risk	Trial registered while recruiting. Pre‐specified primary and secondary outcomes are reported; note omission of PEFR/dyspnoea scale reporting at 40 mins and no data given to support report of "no treatment‐related complications". Clear mistakes in reporting of vital signs.