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

描述（由申请人提供）：本初步研究的总体目标是为全面临床试验提供效应量估计和依据、临床试验和干预可行性数据以及程序材料，该试验将严格测试饮食方法阻止高血压（DASH）作为常规治疗的辅助治疗对控制不佳的哮喘成人的疗效和作用机制。哮喘是一个主要的公共卫生问题，影响全球约3亿人。近几十年来，美国和许多其他西方国家哮喘患病率的急剧增加表明环境在影响这种疾病的复杂遗传学和发育病理生理学方面起着主导作用。作为西化的标志，饮食的迅速变化，包括采用加工程度更高和"方便"的饮食，导致慢性代谢过剩，复合碳水化合物和微量营养素的摄入量相对减少。关于饮食和哮喘之间关系的现有文献采取了简化主义的方法，主要集中在个别营养素上。然而，人们并不吃单一的营养素，而是从不同的群体，形成一个饮食模式的食物组合。DASH包括在哮喘中显示出潜在治疗益处的食物和营养素，但没有干预研究测试了整个饮食作为哮喘治疗的功效。在这项初步研究中，我们将入组90名来自旧金山弗朗西斯科的北方加州Kaiser Permanente的患者，这些患者年龄在18至70岁之间，患有控制不佳的哮喘。受试者将以1：1的比例随机分配至DASH干预组或"常规护理"对照组。DASH干预将在最初的14周内涉及8个小组和3个个人会议，然后是3个月的电话咨询。将在3个月和6个月时进行随访评估。主要目的是评估DASH饮食对经验证的哮喘控制综合指标Juniper哮喘控制问卷的潜在影响。次要结局包括肺功能、哮喘特异性生活质量、急救药物使用、无系统天数和哮喘急性发作。此外，我们将探讨炎症标志物的变化（例如，呼出的一氧化氮分数）对哮喘病理生理学及其对治疗反应的潜在介导作用是重要的。我们还将进行按基因型定义的探索性亚组分析（例如，谷胱甘肽S转移酶基因的多态性）和表型（例如，肥胖症）。此外，本初步研究将提供关键的可行性数据和程序材料，以优化患者招募和保留、干预接受和依从性、合格标准、随机化和设盲程序以及整个试验的数据收集、处理和分析计划。这项研究意义重大，因为它旨在测试一种创新的方法，以改善数百万患有这种常见慢性疾病的美国人的哮喘控制。它符合NHLBI对研究的资助优先权，以增加证据基础，用于完善有关哮喘饮食和其他生活方式改变的临床指南和公共卫生建议。

DESCRIPTION (provided by applicant): The overall objective of this pilot study is to provide effect size estimates and justification, clinical trial and intervention feasibility data, and procedural materials for a full-scale clinical trial that will rigorously test the efficacy and mechanisms of action of the Dietary Approaches to Stop Hypertension (DASH) as adjunct therapy to usual care for adults with not-well-controlled asthma. Asthma is a major public health problem affecting ~300 million people worldwide. The dramatic increase of asthma prevalence in the U.S. and many other westernized countries in recent decades signal a dominant role of the environment in affecting the complex genetics and developmental pathophysiology of this disease. As a hallmark of westernization, rapid changes in diet, including adoption of a more processed and "convenience oriented" diet, have resulted in a chronic metabolic surplus and a relative reduction in the intake of complex carbohydrates and micronutrients. The available literature on the relationship between diet and asthma has taken a reductionist approach by focusing largely on individual nutrients. However, people do not eat individual nutrients, but rather a combination of foods from various groups that form a dietary pattern. The DASH encompasses foods and nutrients that have shown potential therapeutic benefits in asthma, but no intervention study has tested the efficacy of the whole diet as a treatment for asthma. In this pilot study, we will enroll 90 patients of Kaiser Permanente Northern California in San Francisco who are between the ages of 18 and 70 years and have not-well-controlled asthma. Subjects will be randomly assigned in a 1:1 ratio to the DASH intervention or the "usual care" control. The DASH intervention will involve 8 group and 3 individual sessions in the initial 14 weeks, followed by 3 monthly phone consultations. Follow-up assessments will occur at 3 and 6 months. The primary aim is to evaluate the potential effect of the DASH diet on a validated composite measure of asthma control, the Juniper Asthma Control Questionnaire. Secondary outcomes include lung function, asthma-specific quality of life, rescue medication use, system-free days, and asthma exacerbations. Additionally, we will explore changes in inflammatory markers (e.g., fractional exhaled nitric oxide) important to asthma pathophysiology and their potential mediating effects on treatment response. We also will conduct exploratory subgroup analyses defined by genotypes (e.g., polymorphisms on glutathione S transferase gene) and phenotypes (e.g., obesity). Furthermore, this pilot study will provide critical feasibility data and procedura materials to optimize patient accrual and retention, intervention acceptance and adherence, eligibility criteria, randomization and blinding procedures, and data collection, processing and analysis plans for the full trial. This research is significant because it aims to test an innovatie approach to improving asthma control among the millions of Americans with this common chronic disease. It meets NHLBI's funding priority for research to increase the evidence base for refining clinical guidelines and public health recommendations regarding dietary and other lifestyle modifications in asthma.