Study Cited, Design, Primary Outcome, Setting, Quality Rating Inclusion Criteria, Group Size, Baseline Characteristics, Retention at Primary Assessment Time Point Intervention Groups, Component Details Treatment Duration, Total Intervention Contacts, Intervention Adherence Results
Stenius-Aarniala et al. [18]
RCT, ITT (interpreted by reviewer)
PEF was a primary outcome (interpreted by reviewer)
Finland, Medical center
Duration: 1 year
Quality: Good
Inclusion criteria: ages 18-60 yrs, 30≤BMI≤42, with asthma diagnosed with a spontaneous diurnal variation or a bronchodilator response of 15% or more, non-smoker or having stopped smoking for ≤2 yrs before age 50.

N=38

Group n’s
G1: 19
G2: 19

Age, yrs, mean (range)
G1: 49.7 (34-60)
G2: 48.3 (23-60)

Females %
G1: 68.4
G2: 84.2

White %: NR

BMI, kg/m2, mean (range)
G1: 35.8 (31.3-39.4)
G2: 36.7 (32.8-41.8)

The groups were similar for baseline characteristics except rhinitis.

Retention %:
G1: 100
G2: 100
G1: Intervention
Diet during first 8 weeks: a very low calorie dietary preparation (1760 kJ/day [420 kcal/day] containing daily allowances of all essential nutrients)
Medical: received normal medical care throughout the study
Behavior: received education about asthma and allergy via group sessions (details unknown); measured daily morning and evening pre- and post-bronchodilator PEF during the dieting period and thereafter during the 2 weeks before each group meeting.
G2: Control
Diet: no intervention
Medical: same as G1
Behavior: same as G1
Intervention: 14 weeks
Contacts:
G1: 12 group sessions on same education about asthma and allergy as G2
G2: 12 0.5-hour group sessions at the same intervals as G1, during which time themes about asthma and allergy chosen by the group were discussed freely.

Intervention adherence:
Two participants found the consistency or taste of the dietary preparation intolerable but followed a low energy diet. Details NR.
At the end of the 14-week weight loss intervention
Weight change, %, mean
G1: -14.5
G2: -0.3 (calculated by reviewer)
P NR
Weight change, kg, mean (range)
G1: -14.2 (-22.1, -7.7)
G2: -0.3 (NR)
P NR

PEF (% of predicted) change, mean (95% CI)
G1: 4.5 (-0.9, 9.8)
G2: -0.3 (-4.6, 4.1)
P=0.16
FEV1 (% of predicted) change, mean (95% CI)
G1: 5.3 (2.2, 8.4)
G2: -1.5 (-5.1, 2.2)
P=0.006
FVC (% of predicted) change, mean (95% CI)
G1: 1.9 (-0.7, 4.4)
G2: -5.6 (-9.6, -1.5)
P=0.002

Dyspnea symptom, median change on a 100 mm VAS
G1: -13 (variance NR)
G2: -1 (variance NR)
P=0.02

Daily dose of an inhaled bronchodilator, median change
G1: -1.2 (variance NR)
G2: -0.1 (variance NR)
P=0.03
At 1 year (whether primary time point NR)
Weight change, %, mean
G1: -11.3
G2: 2.2
P NR
Weight change, kg, mean (range)
G1: -11.1 (-22.5, -1.1)
G2: 2.3 (NR)
P NR

PEF (% of predicted) change, mean (95% CI)
G1: 5.6 (-0.2, 11.4)
G2: -0.6 (-5.8, 4.7)
P=0.11
FEV1 (% of predicted) change, mean (95% CI)
G1: 4.9 (-0.5, 10.3)
G2: -2.7 (-5.9, 0.5)
P=0.02
FVC (% of predicted) change, mean (95% CI)
G1: 2.0 (-1.4, 5.4)
G2: -5.6 (-8.2, -3.1)
P=0.001

Dyspnea symptom, median change on a 100 mm VAS
G1: NR
G2: NR
P=0.12

Daily dose of an inhaled bronchodilator, median change
G1: NR
G2: NR
P=0.08
Scott et al. [19]
RCT, per protocol completer analysis
Primary outcome is not indicated.
Australia, Medical center
Duration: 10 weeks
Quality: Fair
Inclusion criteria: adults, overweight and obese (28≤BMI≤40), with asthma defined by doctor’s diagnosis and documented history of airway hyperresponsiveness, non-smoking

N=46
Female %: 54.3

Group n’s
G1: 18
G2: 14
G3: 14

Age, yrs, mean (SD)
G1: 44.7 (14.7)
G2: 42.2 (11.5)
G3: 33.9 (11.5)

White %: NR

BMI, kg/m2, mean (SD)
G1: 34.7 (4.0)
G2: 32.8 (2.5)
G3: 32.7 (3.4)

ACQ score, mean (SD)
G1: 1.24 (0.57)
G2: 1.00 (0.71)
G3: 1.36 (0.63)

AQLQ score, median (IQR)
G1: 5.8 (5.4, 6.1)
G2: 6.1 (5.0, 6.3)
G3: 5.8 (4.8, 6.1)

All groups had a similar baseline age, sex, body composition, asthma status, and sputum inflammatory profile.

Retention %:
G1: 83
G2: 71
G3: 93
G1: Dietary intervention
Diet: an intake of 3700–4900 kJ/day (885–1170 kcal/day), including two meal replacements provided free of charge
Behavior: behavior modification and motivational strategies. Participants maintained a daily food dairy during the intervention.
G2: Exercise intervention
Physical activity: a goal of increasing daily steps by 10% each week to a target of 10,000 steps per day. A 12-week gym membership and weekly 1-hour group personal training (both aerobic activities and resistance training) sessions. Participants attended gym ≥3 times/week.
Behavior: participants set goal with dietitian, wore a pedometer daily, and completed a daily physical activity diary during the intervention.
G3: Combined dietary and exercise intervention
Diet: same as G1
Physical activity: same as G2
Behavior: same as G1 + G2
Intervention: 10 weeks
Contacts:
G1: weekly counselling with a dietitian: 7 1-hour clinic visits and 4 10-min phone consultations
G2: weekly 1-hour group training sessions
G3: same as G1 + G2

Intervention adherence:
Diet: energy change, kJ, median (IQR)
G1: -4261 (-5896, -2632)
G2: -232 (-3254, -464)
G3: -5584 (-7384, -4624)
G1 and G3 significantly different from G2

Physical activity: total MET minutes/week change, medium (IQR)
G1: 495 (-825, 3473)
G2: 2651 (389, 7428)
G3: 2267 (691, 4812)
G2 significantly increased total physical activity.
At 10 weeks
Weight change, %, mean (SD)
G1: -8.5 (4.2)
G2: -1.8 (2.6)
G3: -8.3 (4.9)

Weight change, kg, mean (SD)
G1: -8.4 (4.4)
G2: -1.8 (2.7)
G3: -8.2 (5.1)
G1 and G3 significantly different from G2 (P=0.001)

ACQ change, mean (SD)
G1: -0.6 (0.5)
G2: -0.3 (0.5)
G3: -0.5 (0.7)
G1 and G3 significantly improved ACQ score; however, between group comparison is NS (P=0.343).

AQLQ change, median (IQR)
G1: 0.9 (0.4, 1.3)
G2: 0.49 (0.03, 0.78)
G3: 0.5 (0.1, 1.0)
G1, G2, and G3 significantly improved AQLQ score; however, between group comparison is NS (P=0.212).

TLC change, L, median [IQR]
G1: -0.03 (-0.33, 0.14)
G2: 0.13 (-0.02, 0.28)
G3: 0.06 (-0.06, 0.33)
G2 and G3 significantly improved TLC compared with G1 (P=0.037 for overall group difference)

A 5-10% weight loss resulted in clinically significant improvements to ACQ in 58% and AQLQ in 83% of participants.

Women had a significantly greater reduction in sputum percentage neutrophils compared with men (P < 0.05); however, men and women experienced a similar degree of improvement to ACQ and AQLQ.
Dias-Junior et al. [20]
RCT, ITT and per protocol population analysis (patients who lost >10% of body weight)
ACQ was a primary outcome
Brazil, Medical center
Duration: 6 months
Quality: Good
Inclusion criteria: ages 18-65 yrs, BMI ≥30, with severe asthma according to GINA criteria after a 3-month run-in period, with a smoking history of less than 10 pack-years

N=33

Group n’s
G1: 22
G2: 11

Age, yrs, mean (SE)
G1: 42 (15.75)
G2: 44 (24)
P=0.825

Females %
G1: 90.9
G2: 100
P=0.542

White %: NR

BMI, kg/m2, mean (SE)
G1: 39.68 (1.31)
G2: 37.29 (1.07)
P=0.243

ACQ score, mean (SE)
G1: 3.02 (0.19)
G2: 2.91 (0.25)
P=0.718

Retention %:
G1: 100
G2: 100
G1: Intervention
Diet: low caloric intake
Medical: use of sibutramine (10 mg/day) and orlistat (≤120 mg/day)
G2: Control
No intervention
Intervention: 6 months
Contacts:
G1: bimonthly in-person consultations where participants saw the same investigator to have their use of inhaler checked, compliance with medication assessed, and receive education on asthma.
G2: NR

Intervention adherence:
NR
At 6 months (ITT analysis)
BMI, kg/m2, mean (SE)
G1: 36.71 (1.37)
G2: 36.85 (1.06)
P < 0.001 for G1 and NS for G2 within groups
P=0.015 for the comparisons between groups.

ACQ score, mean (SE)
G1: 2.25 (0.28)
G2: 2.90 (0.16)
P=0.001 for G1 and NS for G2 within groups
P=0.044 for the comparisons between groups.

FVC, L, mean (SE)
G1: 2.98 (0.12)
G2: 2.48 (0.12)
P=0.004 for G1 and NS for G2 change within groups
P=0.017 for the comparisons between groups.

ITT analysis showed that the intervention group significantly lost weight (mean weight loss 7.88 kg; 7.5% of baseline weight), improved asthma control as measured by ACQ, and increased FVC.
ACQ reached clinically significant improvements (>0.5) in 11 of the 12 intervention patients who lost >10% of their baseline weight.
Ma et al. [27]
RCT, ITT
ACQ was a primary outcome
USA, Medical center
Duration: 12 months
Quality: Good
Inclusion criteria: ages 18-70 yrs, BMI >30, with uncontrolled persistent asthma confirmed through a multi-stage screening process (i.e., electronic asthma registry queries, completion of the ACT, pre- and post-bronchodilator spirometry, and if necessary, medical chart reviews by an asthma specialist)

N=330
Age, yrs, mean (SD): 47.6 (12.4)
Female %: 70.6
White %: 49.7
BMI, kg/m2, mean (SD): 37.5 (5.9)
ACQ score, mean (SD): 1.4 (0.8)

Group n’s
G1: 165
G2: 165

Between group P values are NS for all baseline characteristics above.

Retention %:
G1: 86
G2: 89
G1: Intervention
Diet: healthy eating with moderate calorie reductions (by 500-1000 kcal/day, but daily total calories ≥1200 kcal)
Physical activity: a goal of ≥150 minutes/week of moderate-intensity physical activity
Behavior: self-management skills (e.g., self-monitoring, action planning, and problem solving); Same as G2
G2: Enhanced usual care control
Diet: no intervention
Physical activity: no intervention
Behavior: received usual care enhanced with a pedometer, a body weight scale, a list of routinely offered weight management services at the participating clinics, and a standard asthma self-management educational DVD
Intervention: 12 months
Contacts:
G1: 13 weekly in-person group sessions over 4 months, 2 monthly in-person individual sessions, ≥3 bimonthly phone consultations over 6 months
G2: none
Intervention adherence:
Physical activity: leisure-time MET minutes/week change, mean (SE)
G1: 418.2 (110.6)
G2: 178.8 (109.1)
P=0.05
Intervention attendance:
Mean (SD) % of 13 weekly group session attended: 77.1% (26.7%)
% participants who attended both monthly individual sessions: 63.6%
% participants who received ≥3 phone consultations: 49%
At 12 months
Weight change, kg, mean (SE)
G1: -4.0 (0.8)
G2: -2.1 (0.8)
P=0.01

Weight change, %, mean (SE)
G1: -4.1 (0.7)
G2: -2.1 (0.7)
P=0.005

ACQ change, mean (SE)
G1: -0.3 (0.1)
G2: -0.2 (0.1)
P=0.92

Weight loss of >10% was associated with a large 1-sample effect size, Cohen’s d=0.76, for ACQ change and with 3.78 (95% CI: 1.72–8.31) times the odds of achieving clinically significant reductions on ACQ as stable weight.

The intervention effects on ACQ change and weight loss at 12 months were comparable among men and women.
ACQ: Asthma control questionnaire; ACT: Asthma control test; BMI, Body mass index; CI, Confidence interval; FEV1: Forced expiratory volume in one second; FVC, Forced vital capacity; GINA, Global initiative for asthma; ITT, Intent-to-treat; IQR, Interquartile range; MET, Metabolic equivalent task; NR, Not reported; NS, Not significant; PEF,Peak expiratory flow; RCT, Randomized controlled trial; SD, Standard deviation; SE, Standard error; TLC, Total lung capacity; VAS, Visual analogue scale.
Table 3: Characteristics of RCTs for weight loss or maintenance interventions in adults with asthma.