Methods | Multicentre, double‐blind, placebo‐controlled trial | |
Participants | 621 participants with severe asthma despite receiving high doses of standard asthma medications
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Interventions | 13 total intravenous infusions of mepolizumab (750 mg), mepolizumab (250 mg), mepolizumab (75 mg) or placebo given every 4 weeks | |
Outcomes | Primary outcomes
Secondary outcomes
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Notes | 52‐week study conducted at 81 centres in 13 countries (Argentina, Australia, Canada, Chile, France, Germany, South Korea, Poland, Romania, Russia, Ukraine, the UK and the USA) Supported by GlaxoSmithKline |
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Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk | Central telephone‐based system and computer‐generated randomly permuted block schedule stratified by whether treatment with OCS was required |
Allocation concealment (selection bias) | Low risk | Mepolizumab and placebo were prepared by unmasked site staff who were not involved in study assessments |
Blinding of participants and personnel (performance bias) All outcomes | Low risk | Mepolizumab and placebo were prepared by unmasked site staff who were not involved in study assessments. Both treatments were identical in appearance and were given to participants by a masked member of the site staff |
Blinding of outcome assessment (detection bias) All outcomes | Low risk | Data analysts were masked to treatment allocation |
Incomplete outcome data (attrition bias) All outcomes | Low risk | All participants accounted for with information on reasons for having withdrawn. Some participants not included in results due to ‘poor efficacy’ |
Selective reporting (reporting bias) | Low risk | No apparent indication of reporting bias |
ACQ: Asthma Control Questionnaire; ALT: alanine aminotransferase; Alk Phos: alkaline phosphatase; AQLQ: Asthma Quality of Life Questionnaire; AST: aspartate aminotransferase; ECP: eosinophil cationic protein; ED: emergency department; FeNO: exhaled fraction of nitric oxide; FEV1 : Forced expiratory volume in 1 second; FP: fluticasone propionate; FVC: forced vital capacity; HRQoL: health‐related quality of life; ICS: inhaled corticosteroid; ICU: intensive care unit; IL: interleukin; IQR: interquartile range; IV: intravenous; JACQ: Juniper Asthma Control Questionnaire; OCS: oral corticosteroids; PC20 : histamine provocative concentration causing a 20% drop in FEV1;PEFR: peak expiratory flow rate; SC: subcutaneous; SD: standard deviation; SGRQ: St. George's Respiratory Questionnaire; ULN: Upper Limit of Normal; VC: vital capacity. aQTc(F): a measure of the time between the start of the Q wave and the end of the T wave in the heart's electrical cycle, corrected for the heart rate using Fredericia's formula.