TABLE 1

Baseline characteristics of studies included in the meta-analysis

Study [ref.]	Study design	Region of study	Study size n	Age at follow up time years	BMI percentile	Asthma control in 12 months/6 months	Asthma exacerbations in 12 months/6 months	Overweight/ Obesity %	Well-controlled asthma %	Hospitalisation %	ED visits %	OCS use %
BREATHE	Cross-sectional	UK, Scotland	1318	4–18	Obesity		OCS use; hospitalisation due to asthma	13.4		15.2		25.9
PACMAN	Cross-sectional	Netherlands	648	4–12	Obesity	ACQ	OCS use; ED visits	10.3	59.0		6.2	5.1
PAGES	Cross-sectional	UK, Scotland	422	4–17	Obesity	ACT	OCS use; hospitalisation due to asthma	15.4	36.2	14.3		39.4
Sasaki [11]	Cross-sectional	Japan	3066	6–11	Obesity	ACT		11.8	85.4
Lang [12]	Cross-sectional	USA	56	10–17	Overweight; obesity	ACQ		62.5 (overweight); 41.1 (obesity)	37.5
Lang [15]	Multicentre clinical trial^#	USA	306		Obesity	ACQ		31	33.7
Lang [16]	Multicentre clinical trial^#	USA	107	6–17	Obesity	ACQ		23.4	71
Kattan [17]	Randomised clinical trial^#	USA	368	12–20	Obesity	ACT		35.1	89.1
Borrell [14]	Cross-sectional	USA	2174	8–19	Overweight; obesity	Asthma control^¶		35.6	17.6
Sah [24]	Cross-sectional	USA	269		Obesity		Hospitalisation due to asthma; ED visits⁺	24.9		32.7	15.6
Schatz [19]	Cohort	USA	10 700	5–17	Obesity		OCS use^§	28.1				11.7
Quinto [20]	Cohort	USA	32 321	5–17	Overweight; obesity		Hospitalisation and ED visits due to asthma; OCS use	19.3 (overweight); 30.0 (obesity)		NA	NA	NA
Luder [23]	Cross-sectional	USA	209	2–18	Overweight		Hospitalisation due to asthma^ƒ; ED visits^##	39.7		23.9	72.2
Hom [21]	Cohort	USA	183	6–18	Overweight		Hospitalisation due to asthma; ED visits^¶¶	59.0		36.1	30.1

^#: findings in these three studies are the results of post hoc analyses of data from randomised clinical trials not specifically designed to assess the effect of obesity on asthma outcomes; ^¶: asthma control based on NHLBI guidelines (meeting at least three criteria has been defined as poor asthma control); ⁺: one time emergency department (ED) visit over the preceding 12 months; ^§: within last 7 days of asthma exacerbations diagnosis; ^ƒ: ≥3 times hospitalisation per year; ^##: ≥10 ED visits during the past year; ^¶¶: ≥1 ED visits during the past 30 days. BMI: body mass index; OCS: oral corticosteroid; ACQ: Asthma Control Questionnaire; ACT: Asthma Control Test; NA: not available.