Chinn S, Britton J R, Burney P G, Tattersfield A E, Papacosta A O
Thorax. 1987 Jan;42(1):45-52. doi: 10.1136/thx.42.1.45.
Epidemiological problems arising from the absence of an agreed definition of asthma have led to the use of bronchial reactivity tests in community surveys of asthma prevalence. Since only a minority of the general population will develop bronchoconstriction in response to the dose of histamine considered acceptable for use in the community it is important to make maximum use of the data available. Several methods for summarising the information in the dose-response curve obtained from a histamine challenge test have been compared. A standardised histamine challenge test was administered to 797 subjects selected from two communities, and a repeat test to 106 subjects. The test was well accepted. For most subjects FEV1 rose initially after administration of histamine (median rise 100 ml), so maximum FEV1 was used as the baseline from which the 20% fall to achieve a PD20 was calculated. In order to use all the data rather than just two points on the FEV1-log dose graph, PD20 was estimated by means of curve fitting, and the values were compared with PD20 from linear interpolation. An exponential curve was found to fit the data well. Extrapolation from the maximum dose of 4 mumol up to 8 mumol was allowed in the estimation of PD20 by both methods. The curve fitting method gave slightly more reproducible PD20 values than did linear interpolation, and also gave more estimates in the range 0.03-8 mumol. The repeatability of PD20 compared well with that of asthmatic subjects tested in a clinical environment. Curve fitting has an advantage over linear interpolation in large community studies, for which analysis of data by computer is essential.
由于缺乏对哮喘的统一界定，导致在社区哮喘患病率调查中出现了一些流行病学问题，因此在这类调查中使用了支气管反应性测试。由于只有少数普通人群会对社区适用的组胺剂量产生支气管收缩反应，所以充分利用现有数据很重要。人们比较了几种总结组胺激发试验剂量反应曲线信息的方法。对从两个社区选取的797名受试者进行了标准化组胺激发试验，并对其中106名受试者进行了重复测试。该测试被广泛接受。对于大多数受试者，给予组胺后FEV1最初会上升（中位数上升100毫升），因此将最大FEV1用作基线，据此计算下降20%以达到PD20所需的剂量。为了使用所有数据而非仅FEV1 - 对数剂量图上的两个点，通过曲线拟合估计PD20，并将这些值与线性插值得到的PD20值进行比较。发现指数曲线能很好地拟合数据。两种方法在估计PD20时都允许从4微摩尔的最大剂量外推至8微摩尔。与线性插值相比，曲线拟合方法得到的PD20值的可重复性略高，并且在范围0.03 - 8微摩尔内给出的估计值更多。PD20的可重复性与在临床环境中测试的哮喘患者的可重复性相当。在大型社区研究中，曲线拟合比线性插值具有优势，这类研究的数据分析必须借助计算机进行。
