NCT01290874.

Methods	Study design: RCT Study grouping: parallel group Open label: yes Cluster RCT: no
Participants	Baseline characteristics No full text available and no results posted on clinicaltrials.gov. The following baseline characteristics were not available for either group Number randomised Number completed Mean age % Male % Predicted FEV1 % White (assumed 0 since the study recruited black participants) Duration of asthma Inclusion criteria: black people (self identified, with ≥ 1 biological parent identified as black; men or women aged 18‐75 years; ability to provide informed consent; clinical history consistent with asthma for > 1 year; ability to perform pulmonary function tests; FEV1 > 40% of predicted; receiving ICS/LABA combination therapy, or ICS moderate‐dose monotherapy; baseline ACQ > 1.25; non‐smoker for past year (total lifetime smoking history < 10 pack‐years) Exclusion criteria: use of equivalent of inhaled fluticasone > 1000 mcg daily; chronic use of OCS or Anti‐IgE for asthma; lung disease other than asthma or diagnosis of vocal cord dysfunction; significant unstable medical illness (other than asthma); pregnancy, lactation, or an unwillingness to maintain effective contraception; significant exacerbation of asthma or respiratory tract infection within 4 weeks; life‐threatening asthma within 5 years; hyposensitisation therapy other than an established maintenance regimen; use of inhaled anticholinergic therapy (ipratropium, tiotropium) within 1 month; known contraindication to inhaled tiotropium (e.g. narrow angle glaucoma, history of bladder neck obstruction or significant symptoms related to prostatic hypertrophy); inability to speak and read English
Interventions	Intervention characteristics LAMA add‐on ICS type/dose: not stated Add‐on type/dose: tiotropium bromide 18 mcg once daily Co‐medications: rescue bronchodilator permitted Type of inhaler: not stated Duration of treatment: 1 year LABA add‐on ICS type/dose: not stated Add‐on type/dose: salmeterol 50 mcg twice daily OR formoterol 12 mcg twice daily for 1 year Co‐medications: rescue bronchodilator permitted Type of inhaler: not stated Duration of treatment: 1 year
Outcomes	No full text available and no results posted on clinicaltrials.gov
Identification	Sponsorship source: Brigham and Women's Hospital with collaboration from Olmsted Medical Center, American Academy of Family Physicians National Research Network, and Harvard Clinical Research Institute Country: US Setting: 13 medical centres and university sites in the US Comments: no results posted and no publications identified Authors name: Elliot Israel, MD Institution: Brigham and Women's Hospital Email: eisrael@partners.org Address: 75 Francis St Boston, MA 02115, US
Notes	None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, no other details
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open label
Blinding of outcome assessment (detection bias) All outcomes	High risk	Study was open label
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No details of number enrolled, number of withdrawals or number included in the analyses
Selective reporting (reporting bias)	High risk	No data published. No publications provided or results posted on clinicaltrials.gov
Other bias	Low risk	None noted