Benefits of weight loss in obese patients with asthma: mechanical or immunological mechanisms?
| ISRCTN | ISRCTN54432221 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN54432221 |
| Protocol serial number | 04/048 |
| Sponsor | University of Liverpool (UK) |
| Funder | Asthma UK (Project ID 04/048). |
- Submission date
- 12/09/2005
- Registration date
- 02/12/2005
- Last edited
- 21/03/2012
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Respiratory
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data
Plain English summary of protocol
Not provided at time of registration
Contact information
Dr John Wilding
Scientific
Scientific
Clinical Sciences Centre
University Hospital Aintree
Liverpool
L9 7AL
United Kingdom
Study information
| Primary study design | Interventional |
|---|---|
| Study design | Randomised controlled trial |
| Secondary study design | Randomised controlled trial |
| Scientific title | |
| Study objectives | Epidemiological studies suggest higher prevalence in obese subjects. Weight loss improves many features of asthma. Whilst lung function will improve with weight loss as a result of mechanical work, it is difficult to explain improvements in bronchial hyper-reactivity and airway inflammation purely on a mechanical basis. Obesity is associated with a state of immune activation that could amplify the process of autoimmunity. We hypothesize that immunological mechanisms partly account for the relationship between obesity and asthma. More specifically, we propose that increased concentrations of the adipokines leptin and tumour necrosis factor alpha and reduced concentrations of adiponectin in obese subjects are promoters of inflammation in asthma, and that improvements in asthma with weight loss are related to changes in the systemic and local (within the bronchial tree) concentrations of these factors as well as a reduction in mechanical work. |
| Ethics approval(s) | Not provided at time of registration |
| Health condition(s) or problem(s) studied | Asthma and obesity |
| Intervention | Dietary intervention: Meal replacement therapy for six months plus dietition advice and support for intervention group versus healthy eating leaflet for control group Exhaled nitric oxide measurements. Methacholine challenge testing - tidal breathing method. Airway resistance with plethysmography. Induced sputum plus sputum cell counts and supernatent inflammatory markers. Blood inflammatory markers. Height, weight and bioimpedence. SGRQ, SF36, IQWOL-LITE questionnaires. Peak flow and symptom diary monitoring. |
| Intervention type | Other |
| Primary outcome measure(s) |
Expected weight loss in the intensive group of 10 to 12 kg (10 - 20% body weight), compared to minimal weight loss in the conventional group. This should result in significant improvements in pulmonary function i.e. reduced bronchoconstriction, reduced peak flow variability and reduced bronchial hyper-reactivity. |
| Key secondary outcome measure(s) |
1. Reduction in systemic inflammation in the intensively treated group |
| Completion date | 01/01/2007 |
Eligibility
| Participant type(s) | Patient |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 80 |
| Key inclusion criteria | 1. Obesity (body mass index more than 30 kg/m^2 2. Age 18 to 65 years 3. Asthma requiring treatment with at least a long-acting inhaled corticosteroid and an inhaled beta agonist |
| Key exclusion criteria | 1. Subjects on long-term oral corticosteroids 2. Diabetes mellitus 3. Pregnancy or breastfeeding 4. History of major eating disorder 5. History of food allergy to any component of Slimfast 6. Major psychiatric disease 7. Current smokers 8. Uncontrolled thyroid disease 9. History of severe cardiac, hepatic or renal disease, malignancy, or any other condition that might, in the opinion of the investigators preclude completion of the study |
| Date of first enrolment | 01/01/2005 |
| Date of final enrolment | 01/01/2007 |
Locations
Countries of recruitment
- United Kingdom
- England
Study participating centre
Clinical Sciences Centre
Liverpool
L9 7AL
United Kingdom
L9 7AL
United Kingdom
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | |
| IPD sharing plan |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Results article | results | 01/03/2012 | Yes | No |
