The DASH Diet for Adults With Uncontrolled Asthma

Study Overview
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Brief Summary
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Dietary intervention efficacy trials are distinctly lacking in asthma research. This pilot study aims to provide effect size estimates and justification, clinical trial and intervention feasibility data, and procedural materials for a full-scale randomized controlled trial that will determine the efficacy and mechanisms of action of the Dietary Approaches to Stop Hypertension (DASH)-a recommended dietary pattern based on proven cardiovascular benefits-as adjunct therapy to standard care for adults with uncontrolled asthma.

Detailed Description
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Dietary intervention efficacy trials are distinctly lacking in asthma research. This pilot study aims to provide effect size estimates and justification, clinical trial and intervention feasibility data, and procedural materials for a full-scale randomized controlled trial that will determine the efficacy and mechanisms of action of the Dietary Approaches to Stop Hypertension (DASH)-a recommended dietary pattern based on proven cardiovascular benefits-as adjunct therapy to standard care for adults with uncontrolled asthma. Eligible, consenting participants (n=90) will be randomized to receive usual care alone or combined with a DASH intervention. Follow-up assessments will occur at 3 and 6 months. By evaluating a dietary pattern approach to improving asthma control, this study could advance the evidence base for refining clinical guidelines and public health recommendations regarding the role of dietary modifications in asthma management.

Official Title
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A Pilot Study of the DASH Diet in Not-Well-Controlled Adult Asthma

Conditions
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Asthma, Hypertension

Intervention / Treatment
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* Behavioral: Dietary Approaches to Stop Hypertension dietary pattern


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ethnicity: All ethnic groups Body mass index (BMI) 18.5-39.9 kg/m2 Suboptimally controlled asthma: Diagnosis of asthma on the current medical problem list Currently prescribed at least 1 medication for the treatment of asthma Physiological evidence of asthma with demonstrable reversibility of airway obstruction, or a specialist's confirmation of asthma diagnosis based on chart review Documented history of high asthma-related emergency and/or inpatient encounters or reliever medication usage Asthma Control Test: total score <20 or item score <3 for any of the first 4 questions regarding symptoms (3-6x/week or more), nighttime awakening (1x/week or more), interference with normal activity (at least some of the time), and rescue medication use for symptom relief (2-3x/week or more) Kaiser member for ≥1 year PCP approval of study screening Able and willing to enroll and provide written informed consent Exclusion Criteria: Intermittent asthma, defined as either seasonal asthma or (daytime asthma symptoms <2x/week and nocturnal symptoms <2x/month and no use of long-term control medications) Primary diagnosis of COPD (emphysema or chronic bronchitis) on the current medical problem list or suggested by baseline spirometry and smoking history Previous diabetes (other than during pregnancy) or diabetes diagnosed as a result of fasting blood glucose or hemoglobin A1c levels obtained at screening Previous cardiovascular disease: e.g., coronary heart disease, cerebrovascular disease, peripheral vascular disease, heart failure, or aortic aneurysm Diagnosis of cancer (other than non-melanoma skin cancer) that is/was active or treated with radiation or chemotherapy within the past 2 years Inflammatory bowel disease, colostomy, malabsorption, or major gastrointestinal resection Diagnosis of bipolar or psychotic disorder or hospitalization for psychological or emotional problems within the last 2 years Diagnosis of a terminal illness and/or in hospice care Fasting LDL cholesterol >190 mg/dL, triglycerides >500 mg/dl, fasting blood glucose >125 mg/dl Significant liver enzyme abnormality as indicated by AST or ALT more than 2 times the upper limit of normal or a clinical diagnosis of hepatitis Renal insufficiency (GFR<60 ml/min) Current use of insulin or oral hypoglycemic agents Use of oral corticosteroids >5 days/month on average Current use of medications for treatment of psychosis or manic-depressive illness Current use of prescription or non-prescription weight-loss products or any dietary/herbal supplements and unwillingness to discontinue; Inability to speak, read, or understand English at the 6th-grade level or above Inability to perform pulmonary function tests by spirometry in a consistent manner DASH concordance index >60% Unwillingness to modify current diet Current or planned participation in a structured program that overtly focuses on diet and nutrition Planning to undergo bariatric surgery during the study period Actively attempting to lose weight, or weight change >15 lbs during prior 3 months Consumption of >21 alcoholic drinks per week, or >=6 drinks on one occasion twice or more per week, or alcoholism as determined by the Alcohol Use Disorders Identification Test Pregnant, lactating, or planning to become pregnant during the study period No longer a Kaiser patient or planning to transfer care out of Kaiser or to move out of the area during the study period Family/household member of another study participant or of a study staff member Enrolled or planning to enroll in another research study that would limit full participation in the study or confound the interpretation of the study's findings Investigator discretion for safety or protocol adherence reasons

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Health Services Research
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Usual Care<br>Usual Care | |
| Experimental: DASH Intervention<br>Dietary Approaches to Stop Hypertension dietary pattern. Usual care in combination with a DASH intervention consisting of 8 group and 3 individual sessions over 3 months, followed by 3 monthly phone consultations. | Behavioral: Dietary Approaches to Stop Hypertension dietary pattern<br>* The intervention will employ a series of small group and individual sessions, followed by periodic telephone contacts, to help participants make appropriate dietary changes and develop the skills to maintain these changes over the long term. The initial 3 months of intensive intervention will involve 8 group and 3 individual sessions for 45-60 minutes each. During the next 3 months, participants will receive counseling phone calls once per month for 20-30 minutes each call. Group session sizes may range from 8-15 participants.<br>* Other names: DASH;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 7-item Juniper Asthma Control Questionnaire (ACQ) | The ACQ provides a reliable, validated assessment of asthma control focusing on current impairment. Its 7 items assess the components of current asthma impairment as defined in the asthma treatment guidelines, i.e., daytime and nocturnal asthma symptoms, activity limitations, rescue medication use (excluding use to prevent exercise-induced bronchospasm), and lung function (FEV1). The ACQ is the only guideline-recommended composite measure of asthma control that includes lung function in its overall rating. | 6-months post-randomizaton | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Lung function | Lung function measured by spirometry | 6-months post-randomization | 
| Asthma specific Quality of Life | Juniper Mini Asthma Quality of Life Questionnaire (Mini-AQLQ) | 6-months post-randomization | 
| Asthma symptom-free and β2-agonist-free days | Asthma symptom-free and β2-agonist-free days will be calculated from 2-week asthma symptom diaries. | 6-months post-randomization | 
| Asthma-related health care utilization | Asthma-related health care utilization will be assessed through data extraction from Kaiser Permanente (KP) electronic databases for the periods of 6 months pre- and post-randomization | 6 months pre-and post-randomization | 
| Diet adherence | Participants' adherence to the DASH diet will be assessed by multiple-pass 24-hour diet recalls for servings of fruits, vegetables, dairy products, and whole grains; increases in serum carotenoids, folate and vitamin B12; and reductions in fasting plasma lipids. | 6-months post-randomization | 
| Psychosocial predictors of dietary change | Self-efficacy and social support for dietary change will be assessed using previously validated instruments. | 6-months post-randomization | 
| Comorbidities | Sleep apnea and gastroesophageal reflux disease (GERD) are common comorbidities of obesity and asthma. The Berlin Questionnaire for Sleep Apnea and the GERD Symptom Assessment Scale will be administered to screen for these conditions and to assess changes in symptoms. In addition, the Pittsburgh Sleep Quality Index will be used to assess participants' usual sleep habits and sleep quality. The 9-item Patient Health Questionnaire (PHQ-9) is both a measure of depressive symptomatology and a tentative diagnostic instrument for the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) depressive disorders. | 6-months post-randomization | 
| Generic health related Quality of Life | The 12-item Short Form Health Survey (SF-12) is a widely used measure to assess non-disease specific physical and mental health status. | 6-months post-randomization | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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DASH, diet, asthma, adults, asthma control