Table 2. Summary of major clinical trials on the effects of controlling comorbidity on asthma outcomes in adults.

First author (year)ref	Participants	Study design and intervention	Main findings on the intervention
Dixon (2014)80	237 adults and 151 children with chronic sinonasal disease and inadequately controlled asthma (median age 27 years old)	24-week randomized double-blind placebo-controlled trial, intranasal mometasone versus placebo	In adults, there was a small difference in asthma symptoms and in nasal symptoms, but no difference in asthma quality of life, lung function, or episodes of poorly controlled asthma.
Gevaert (2012)82	24 patients with nasal polyps and asthma (median age around 50 years old)	16-week randomized double-blind placebo-controlled trial, omalizumab versus placebo	There was a significant decrease in endoscopic polyp scores and Lund-Mackay score, and also in upper and lower airway symptoms and quality of life scores.
Stenius-Aarniala (2000)83	38 patients with asthma and obesity (BMI 30-42 kg/m2, age 18-60 years old)	1-year randomized open-labelled controlled trial, supervised weight reduction program with 8-week very low energy diet versus standard care	There were significant reduction in body weight (14.5%) and also improvements in lung function parameters (FEV1 and FVC), dyspnea scale, rescue medication use, and exacerbation frequency.
Dias-Júnior (2014)84	33 patients with severe asthma and obesity (mean BMI 39 kg/m2, mean age 42 years old)	6-month randomized open-labelled controlled trial, weight loss program (low caloric intake, sibutramine 10 mg per day, and orlistat maximum 120 mg per day) versus standard care	There were significant reduction in body weight (7.5%) and also improvements in asthma control and FVC.
Chaudhuri (2006)85	32 smokers with asthma (mean age 47 years old, 36 pack-year)	6-week, non-randomized open controlled trial, smoking cessation	There were significant improvement in FEV1 and reduction in sputum neutrophils.
Tønnesen (2005)86	220 smokers with asthma (mean age 35 years old, 19 pack-year)	4-month, randomized open controlled trial, complete smoking cessation versus smoking reduction to fewer than seven cigarettes/day versus continuation of usual smoking	There were significant improvements in asthma-specific quality of life score, reductions in self-reported day and night use of rescue β2-agonists, doses of inhaled corticosteroids, in daytime asthma symptoms, and in bronchial hyperreactivity.

BMI, body mass index; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity.