Asthma
Conditions
Brief summary
The study is a randomized, crossover meal-replacement pilot intervention to determine feasibility of a larger scale dietary trial in asthma and gather preliminary evidence for the impact of a healthy diet on asthma outcomes. Participants with doctor-diagnosed asthma were randomized to crossover trial of a 4-week dietary intervention or usual diet with a 4-week washout period. During the dietary intervention, all meals and snacks were provided by the study.
Detailed description
The objective of the study is to demonstrate feasibility of a randomized, controlled clinical trial of a dietary intervention in a population of adults with asthma and to determine sample size estimates for a larger, more definitive trial aimed at improving asthma clinical outcomes and improving markers of inflammation and oxidative stress. The study uses a feeding trial design comprised of a 4 week dietary intervention in which all meals are provided to study participants and a 4 week control diet comprised of usual dietary intake. Participants are randomized to the intervention or control diet and then cross over to the alternate assignment after a 4 week washout period.
Interventions
OTHERhealthy diet
Participants were provided meals and snacks for one month that represented a healthy diet that is high in unsaturated fats, approximating a Mediterranean diet
Sponsors
Johns Hopkins University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
No
Inclusion criteria
* ages 18-50, self-reported physician diagnosis and treatment for asthma within the 12 months prior to enrollment, stable asthma defined as no asthma exacerbation (emergency department visit, systemic steroid treatment, or urgent care visit) or respiratory infection in the 4 weeks prior to enrollment.
Exclusion criteria
* active smokers,pregnant or breastfeeding, using systemic corticosteroids or warfarin, had another major pulmonary diagnosis or significant systemic illness, reported excessive alcohol consumption (over 14 drinks per week or six or more drinks on one or more occasions per week), reported food allergy, or weighed over 350 pounds or changed weight by over ten pounds in the two months prior to screening
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Feasibility as assessed by the number of participant drop outs | Change from baseline and 4 weeks | Feasibility will be assessed by the number of drop outs. |
| Adherence using 24 hour diet recall | Change from baseline to 4 weeks | Adherence to the dietary intervention will be assessed using self-report of dietary intake via 24 hour dietary recall. |
| Adherence assessed by serum carotenoids | Change from baseline to 4 weeks | Serum carotenoids will be measured at baseline and at 4 weeks. An increase in serum carotenoids is expected with adherence to the dietary intervention. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Asthma status | Difference between baseline and 4 weeks | Asthma Control Test (ACT, range 5-25, higher score denoting better asthma control). The change in score between baseline and week 4 will be assessed. |
| Asthma Symptom Utility Index | Difference between baseline and 4 weeks | Asthma Symptom Utility Index (ASUI, range 0-1, higher score denoting fewer symptoms) will be measured and the difference between week 4 and week 0 will be assessed. |
| FEV1 | Difference between baseline and 4 weeks | Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1) will be assessed and compared between baseline and 4 weeks after the dietary intervention |
| Exhaled nitric oxide | Difference between baseline and 4 weeks | Exhaled nitric oxide is an indicator of airway inflammation and will be measured according to American Thoracic Society standards at baseline and 4 weeks. |
| Adherence assessed by serum carotenoids | Difference between baseline and 2 weeks | Serum carotenoids will be measured at baseline and at 4 weeks. An increase in serum carotenoids is expected with adherence to the dietary intervention. |
| Asthma Quality of Life Questionnaire (AQLQ) | Difference between baseline and 4 weeks | Asthma Quality of Life Questionnaire (AQLQ) is a 32 item questionnaire and each question uses a 7-point Likert scale (7 = not impaired at all; - 1 = severely impaired). Scores between week 0 (baseline) and week 4 will be assessed. |
| FVC | Difference between baseline and 2 weeks | Spirometry will be measured according to the American Thoracic Society standards. The forced vital capacity (FVC) will be assessed and compared between baseline and 4 weeks after the dietary intervention |
| FEV1/FVC ratio | Difference between baseline and 4 weeks | Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio will be assessed and compared between baseline and 4 weeks after the dietary intervention |
Outcome results
None listed