Devereux G, Beach J R, Bromly C, Avery A J, Ayatollahi S M, Williams S M, Stenton S C, Bourke S J, Hendrick D J
Chest Unit, Newcastle General Hospital, University of Newcastle upon Tyne, UK.
Thorax. 1995 Sep;50(9):941-7. doi: 10.1136/thx.50.9.941.
Although several investigations have shown a relationship between asthma (or its surrogate, airways responsiveness) and dietary or urinary sodium, others have not, and the matter remains controversial. This "salt effect" has been investigated during two recent epidemiological surveys of men in northern England. The first assessed the possible effect on airways responsiveness of occupational exposure to welding fumes, and the second characterised airways responsiveness in two geographically distinct residential areas. Thus, three separate study areas/populations were involved.
Investigation 1 involved 1059 shipyard workers aged 16-27 years who were exposed variously to welding fumes, and Investigation 2 involved 587 men aged 20-44 years who lived in rural West Cumbria or in urban Newcastle upon Tyne. In Investigation 1, a 24 hour urine specimen was requested from each subject with quantifiable airways responsiveness (PD20 < or = 6400 micrograms methacholine) and from an equal number of subjects without measurable airways responsiveness from the same occupational subgroup. In Investigation 2, every subject was asked to provide a 24 hour urine specimen.
Of the men undergoing methacholine tests, satisfactory 24 hour urine specimens were obtained from 234 (22.1%) in Investigation 1 and 232 (39.5%) in Investigation 2. Analysis using multiple linear regression, multiple linear logistic regression, and multiple regression for censored data produced consistent results within each study population but conflicting results between them, such that there was no hint of a relationship between airways responsiveness and 24 hour urinary sodium excretion in the shipyard workers of Investigation 1 nor in the rural West Cumbrian population of Investigation 2, but an association was found in the urban Newcastle population of Investigation 2. All study populations were sufficiently large to demonstrate anticipated relationships between airways responsiveness and atopy, baseline FEV1, and (Newcastle only) age.
If airways responsiveness is related to dietary sodium the relationship is not likely to be strong.
尽管多项研究表明哮喘（或其替代指标，气道反应性）与饮食或尿钠之间存在关联，但其他研究并未得出此结论，该问题仍存在争议。在最近对英格兰北部男性进行的两项流行病学调查中对这种“盐效应”进行了研究。第一项调查评估了职业性接触焊接烟雾对气道反应性的可能影响，第二项调查则对两个地理位置不同的居民区的气道反应性进行了特征描述。因此，涉及了三个独立的研究区域/人群。
调查1涉及1059名年龄在16 - 27岁之间、不同程度接触焊接烟雾的造船厂工人，调查2涉及587名年龄在20 - 44岁之间、居住在西坎布里亚农村或泰恩河畔纽卡斯尔市的男性。在调查1中，要求每个气道反应性可量化（PD20≤6400微克乙酰甲胆碱）的受试者以及来自同一职业亚组的同等数量气道反应性不可测量的受试者提供24小时尿液样本。在调查2中，要求每个受试者提供24小时尿液样本。
在接受乙酰甲胆碱测试的男性中，调查1中有234名（22.1%）、调查2中有232名（39.5%）获得了满意的24小时尿液样本。使用多元线性回归、多元线性逻辑回归以及对删失数据的多元回归分析在每个研究人群中得出了一致的结果，但在不同人群之间结果相互矛盾，即调查1中的造船厂工人以及调查2中西坎布里亚农村人群的气道反应性与24小时尿钠排泄之间没有关联迹象，但在调查2中的纽卡斯尔市城市人群中发现了关联。所有研究人群规模都足够大，足以证明气道反应性与特应性、基线第一秒用力呼气容积以及（仅在纽卡斯尔）年龄之间的预期关系。
如果气道反应性与饮食钠有关，这种关系可能并不强烈。
