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

描述(由申请人提供)：这项试验性研究的总体目标是为一项全面的临床试验提供有效规模的估计和理由、临床试验和干预可行性数据以及程序性材料，该试验将严格测试作为常规护理的辅助疗法的抗高血压饮食疗法(DASH)作为对成人哮喘控制不佳的疗效和作用机制。哮喘是一个主要的公共卫生问题，影响着全球约3亿人。近几十年来，美国和许多其他西化国家哮喘患病率的急剧上升表明，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发挥了主导作用。作为西方化的一个标志，饮食的快速变化，包括采用加工程度更高、以方便为导向的饮食，导致长期代谢过剩，复杂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采取了一种简单化的方法，主要集中在个别营养素上。然而，人们并不吃个别的营养素，而是来自不同群体的食物的组合，形成了一种饮食模式。DASH包含了已经显示出对哮喘潜在治疗益处的食物和营养物质，但还没有干预研究测试整个饮食作为哮喘治疗的有效性。在这项初步研究中，我们将在旧金山招募90名年龄在18岁至70岁之间、哮喘控制不佳的北加州凯撒永久医院的患者。受试者将按1：1的比例随机分配到DASH干预组或“常规护理”对照组。DASH干预将在最初的14周内包括8个小组和3个人，然后每月进行3次电话咨询。后续评估将在3个月和6个月进行。主要目的是评估DASH饮食对有效的哮喘控制综合指标--Juniper哮喘控制问卷--的潜在影响。次要结果包括肺功能、哮喘特有的生活质量、抢救药物的使用、无系统日和哮喘加重。此外，我们还将探讨哮喘病理生理学中重要的炎性标志物(例如呼出的一氧化氮)的变化及其对治疗反应的潜在中介作用。我们还将进行由基因类型(例如谷胱甘肽S转移酶基因的多态)和表型(例如肥胖)定义的探索性亚组分析。此外，这项试点研究将提供关键的可行性数据和程序材料，以优化患者的应计和保留、干预接受和遵守、资格标准、随机和盲法程序，以及全面试验的数据收集、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病的美国人的哮喘控制。它符合NHLBI为研究增加证据基础的资助优先事项，以完善关于哮喘患者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.