Ohta 2009.

Methods	Randomised, double‐blind, parallel‐group, multi‐centre study
Participants	Treatment group: 158. Age: 48.8 (14.88). Males: 74 (46.8%). Baseline lung function: mean % predicted FEV1 (SD): 74.06 (19.91) Control group: 169. Age: 49.2 (14.42). Males: 70 (42.7%). Baseline lung function: mean % predicted FEV1 (SD): 75.81 (20.89) Inclusion criteria stated as: males and females with inadequately controlled allergic asthma for > one year (positive skin prick test), 20 to 75 years, weighing 30 to 150 kg, with allergic asthma, IgE level 30 to 700 IU/mL, taking inhaled corticosteroids at a dosage of BDP 800 μg/d (or equivalent) and at least one more drug for managing their asthma at least three months before trial observation (e.g. oral corticosteroids, β2‐agonists (oral, inhaled or patch‐type) theophylline, leukotriene‐3 antagonists or a thromboxane A2 inhibitor/antagonist) Exclusion criteria stated as: pregnant or breast‐feeding, history of severe anaphylactic reaction or anaphylactoid reaction, patients taking unacceptable medications (e.g. > 10 mg of prednisolone‐equivalent oral corticosteroids, immunosuppressants), significant underlying medical conditions that could impact interpretation of results Location(s): 73 centres in Japan
Interventions	Subcutaneous dose of omalizumab was based on participant's body weight and total serum IgE level at visit 1 and was at least 0.016 mg/kg/IgE (IU/mL) every four weeks or 0.008 mg/kg/IgE (IU/mL) every two weeks versus placebo Background inhaled corticosteroid dose > 1000 µg beclometasone dipropionate equivalent per day Participants using oral corticosteroids at baseline included but no further details given
Outcomes	Morning peak expiratory flow (PEF) at baseline and at end of treatment, pulmonary function parameters measured by spirometer, frequency of rescue medication use, symptoms score, activities of daily living score, night‐time sleep score, adverse events
Notes	Two‐week pretreatment phase, 16‐week treatment phase and 12‐week follow‐up Co‐medication: doses of ICS and other concomitant asthma medications were kept constant for one month before pretreatment phase and were maintained during treatment phase. Participants were permitted to use rescue medication as needed. If any worsening of asthma occurred, which required additional treatment with a systemic corticosteroid, the participant was discontinued from the study
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Stated as: randomised and allocated to receive either omalizumab or placebo using a third party’s central registration system
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐blind but unclear whether blinding continued beyond end of 16‐week treatment phase
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Unbalanced withdrawals from groups (8.2% from treatment group vs 16.6% from placebo group)
Selective reporting (reporting bias)	Unclear risk	All outcome measures reported with exception of serum IgE levels and correlation with efficacy and other pharmacological measurements