Camargo 2003a.

Methods	Randomised, parallel group trial Withdrawals: stated Intention‐to‐treat: stated.
Participants	N: 134 (low dose treatment: 68; control: 66) % females: treatment 56.3%; control 60.6% Mean age: treatment 35.7; control 34.5 Setting: ED Baseline severity: FEV1 < 70% or increase/decrease </= 20% points after initial beta2‐agonist Inclusion criteria: 15 to 54 years; diagnosis of asthma > 1 year; < 10 pack years smoking history; not currently on systemic steroids/leukotriene modulators/anticholinergics/long‐acting beta2‐agonists Exclusion criteria: Patients with pneumonia, congestive heart failure, or other clinical explanations for dyspnea were excluded, as were patients with significant comorbid disorders requiring acute management; FEV1 > 70% or increase/decrease >/= 20% points after initial beta2‐agonist
Interventions	Treatment Intravenous montelukast 7 mg in addition to usual care given over 5 minutes Control Exact matching placebo in addition to usual care Usual care: Nebulised beta2‐agonist; O2; steroids as required; post‐discharge: 5‐day course of prednisone; follow‐up at 14 days ±3 days Study duration: Acute: spirometry at 20 minutes, if improved then discharged, otherwise spirometry repeated at intervals up to 6 hours, F/U 14 days ± 3 days
Outcomes	Primary outcome: % change in FEV1 at 20 mins Secondary outcomes: treatment failure (hospitalisation, need for treatments outside study protocol (anticholinergics, magnesium, systemic beta2‐agonist, xanthines, or need for > 6hours active treatment); proportion of participants receiving steroids or beta2‐agonists during study period; proportion of participants given > 2 beta2‐agonists after study drug
Notes	Also measured urinary leukotriene E4
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation schedule with a blocking factor of six to receive study drug
Allocation concealment (selection bias)	Low risk	"Allocation numbers were encoded on labels included with the study drug, and patients were assigned the next available allocation number in sequence at each site"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Patients, investigators, and the in‐house research team were not aware of actual treatment allocations at any point during the study. The allocation code was not broken until after the study was completed and the dataset was declared final" "Double‐blind (with in‐house blinding procedures)" "Intravenous montelukast (7 mg or 14 mg) or exact matching placebo was supplied as a lyophilized powder together with diluent (3.3% dextrose/0.3% normal saline). The study drug was reconstituted by a qualified individual not otherwise involved with the care of the patient and was administered as a manual bolus over 5 minutes"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	See above
Incomplete outcome data (attrition bias) All outcomes	Low risk	Lost to follow‐up (intervention: placebo) = 0:0 Small number discontinued intervention A protocol was indicated, but we have not seen it