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

描述（由申请人提供）：本试点研究的总体目标是为一项全面的临床试验提供效应量估计和论证、临床试验和干预可行性数据以及程序材料，该临床试验将严格测试饮食方法停止高血压（DASH）作为成人哮喘控制不良好的常规护理辅助治疗的疗效和作用机制。哮喘是影响全世界约3亿人的主要公共卫生问题。近几十年来，美国和许多其他西方化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。作为西方化的一个标志，饮食的快速变化，包括采用更加工和“方便导向”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。现有的关于饮食和哮喘之间关系的文献主要集中在单个营养素上，采取了一种简化的方法。然而，人们吃的不是单独的营养素，而是各种食物的组合，形成了一种饮食模式。DASH包含了对哮喘有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。在这项试点研究中，我们将招募90名年龄在18岁至70岁之间、哮喘控制不佳的旧金山Kaiser Permanente北加州患者。受试者将按1:1的比例随机分配到DASH干预组或“常规护理”组。DASH干预将在最初的14周内包括8个小组和3个个人会议，随后每月进行3次电话咨询。随访评估将在3个月和6个月时进行。主要目的是评估DASH饮食对哮喘控制的一种有效的复合测量方法——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、抢救用药、系统无症状天数和哮喘加重。此外，我们将探讨炎症标志物的变化（例如，呼出一氧化氮分数）对哮喘病理生理的重要作用及其对治疗反应的潜在介导作用。我们还将通过基因型（如谷胱甘肽S转移酶基因多态性）和表型（如肥胖）进行探索性亚组分析。此外，该试点研究将提供关键的可行性数据和程序材料，以优化患者累积和保留，干预接受和依从性，资格标准，随机化和盲化程序，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对研究的资助重点，以增加证据基础，以完善关于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.