Subgroup Analysis of a Randomized Trial of the Effects of Positive Messaging on Patient-Reported Outcomes with Asthma – Effect of Obesity

Figures & data

Figure 1 Consort diagram. Data from intervention groups included in blue box were included in the analysis of change in patient-reported outcome.

Table 1 Baseline Characteristics

Characteristic	Total (N= 600)	Non-Obese (N= 373)	Obese (N= 227)	P-value*
Age, Median(IQR)	37 (26, 48)	34 (24, 47)	41 (30, 50)	<0.001
Male, N (%)	164 (27%)	123 (33%)	41 (18%)	<0.001
Race or ethnic group, N (%)
White	349 (58%)	242 (65%)	107 (47%)	<0.001
Black	196 (33%)	95 (25%)	101 (44%)
Hispanic	37 (6%)	23 (6%)	14 (6%)
Other	18 (3%)	13 (3%)	5 (2%)
BMI, Median(IQR)	27 (24, 34)	24 (22, 27)	36 (33, 41)	<0.001
Former smoker, N(%)	88 (15%)	45 (12%)	43 (19%)	0.021
Socioeconomic
Education, N(%)
<High school	49 (8%)	28 (8%)	21 (9%)	<0.001
High school or equivalent	86 (14%)	42 (11%)	44 (19%)
Some college	260 (43%)	148 (40%)	112 (49%)
Bachelor’s Degree	113 (19%)	86 (23%)	27 (12%)
Some post graduate studies	36 (6%)	25 (7%)	11 (5%)
Post graduate degree	56 (9%)	44 (12%)	12 (5%)
Employment, N(%)
Student	99 (17%)	81 (22%)	18 (8%)	<0.001
Not working outside the home	62 (10%)	32 (9%)	30 (13%)
Currently employed full time	294 (49%)	184 (49%)	110 (48%)
Currently employed part time	70 (12%)	42 (11%)	28 (12%)
Retired	29 (5%)	18 (5%)	11 (5%)
Disabled, unable to work	24 (4%)	6 (2%)	18 (8%)
Other	22 (4%)	10 (3%)	12 (5%)
Combined household income
<$20,000	127 (21%)	71 (19%)	56 (25%)	0.389
$20,000-$50,000	184 (31%)	110 (29%)	74 (33%)
>$50,000-$75,000	68 (11%)	45 (12%)	23 (10%)
>$75,000	66 (11%)	46 (12%)	20 (9%)
Declined to answer	114 (19%)	74 (20%)	40 (18%)
Unknown	41 (7%)	27 (7%)	14 (6%)
Asthma Characteristics
Age of asthma onset, Median (IQR)	13 (4, 29)	12 (4, 25)	18 (5, 35)	0.007
Use inhaled short-acting beta-agonist ≥2x per week	505 (84%)	319 (86%)	186 (82%)	0.243
Daily use of ICS or ICS/LABA	325 (54%)	192 (51%)	133 (59%)	0.090
Asthma Questionnaires, Median (IQR)
ACQ6 Score (↓ range: 0–6)	1.5 (0.8, 2.0)	1.3 (0.8, 1.8)	1.7 (1.0, 2.3)	<0.001
AQLQ Score (↑ range: 0–7)	5.1 (4.1, 5.9)	5.4 (4.4, 6.0)	4.7 (3.9, 5.4)	<0.001
ASUI Score (↑ range: 0–1)	0.80 (0.69, 0.88)	0.83 (0.73, 0.89)	0.77 (0.64, 0.84)	<0.001
Spirometry, Median(IQR)
Pre-BD FEV1^‡	2.68 (2.23, 3.19)	2.82 (2.40, 3.33)	2.41 (2.00, 2.91)	<0.001
Pre-BD %Predicted FEV1^‡	86 (77, 94)	86 (78, 95)	86 (75, 93)	0.172
Post-BD FEV1^‡	2.90 (2.43, 3.42)	3.07 (2.61, 3.59)	2.59 (2.18, 3.06)	<0.001
Post-BD % Predicted FEV1^‡	92 (84, 101)	93 (85, 102)	91 (81, 99)	0.004
% change FEV1 from BD^‡	6.2 (3.0, 12.5)	6.5 (3.4, 12.8)	5.9 (2.2, 11.6)	0.057
Pre-BD FVC^‡	3.55 (2.92, 4.27)	3.75 (3.15, 4.53)	3.19 (2.69, 3.84)	<0.001
Pre-BD % Predicted FVC^‡	94 (85, 103)	95 (87, 105)	91 (83, 101)	<0.001
Post-BD FVC^‡	3.65 (3.07, 4.43)	3.87 (3.24, 4.61)	3.29 (2.78, 3.99)	<0.001
Post-BD % Predicted FVC^‡	96 (89, 106)	98 (90, 107)	94 (86, 103)	<0.001
% change FVC from BD^‡	2.1 (−0.5, 5.3)	1.8 (−0.2, 4.8)	2.4 (−0.7, 6.5)	0.602
Pre-BD Peak Flow^‡	380 (330, 450)	390 (340, 460)	370 (320, 430)	0.023
Pre-BD FEV1/FVC ratio^‡	0.76 (0.69, 0.81)	0.75 (0.69, 0.81)	0.77 (0.71, 0.82)	0.069
Post-BD FEV1/FVC ratio^‡	0.79 (0.74, 0.85)	0.79 (0.73, 0.85)	0.80 (0.75, 0.84)	0.859
% change from BD FEV1/FVC ratio^‡	4.16 (1.63, 7.94)	4.89 (2.01, 8.84)	3.22 (1.34, 5.97)	<0.001

Notes: *P-values are based upon Chi-squared and Kruskal–Wallis tests for categorical and continuous characteristics, respectively. ↑ High scores indicate better health. ↓ Low scores indicate better health. ^‡Predicted values for FEV₁ and FVC are taken from: Hankinson JL et al.²²

Abbreviations: SD, standard deviation; DI, metered dose inhaler; Neb, nebulizer; ICS, inhaled corticosteroids; LABA, long-acting beta-agonist; ACQ6, Asthma Control Score; ASUI, Asthma Symptom Utility Index; AQLQ, Asthma Quality of Life; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; BD, bronchodilator.

Figure 2 Change in scores by intervention group and obesity status, mean and 95% confidence intervals by messaging and obesity for (A) ACQ6, (B) AQLQ and (C) ASUI. Estimates of change from baseline values at two visits (2 and 4 weeks post randomization) from linear regression, mixed effects models.

McFadden ER Jr, Luparello T, Lyons HA, Bleecker E. The mechanism of action of suggestion in the induction of acute asthma attacks. Psychosom Med. 1969;31(2):134–143. PMID: 5784000. doi:10.1097/00006842-196903000-00007

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