Children's Hospital, Virgen del Rocío, Seville, Spain.
Neurogastroenterol Motil. 2013 Aug;25(8):664-9. doi: 10.1111/nmo.12143. Epub 2013 May 3.
The evaluation of symptom association in gastroesophageal reflux is an open problem. The scientific literature reports important deficiencies and clinicians are claiming a new methodology. This article provides an optimal method for the evaluation of symptom association, the binomial symptom index (BSI).
A mathematical description of the BSI was presented for the study of association and causality. A total of n = 850,000 patients were simulated using a Monte Carlo model to perform a two-way sensitivity analysis. The average and the standard deviation of the BSI were evaluated in groups of 5000 patients with the same values of the reflux rate, symptom rate, association ratio, window of association, and monitoring time in order to contrast their influence on the estimator.
The BSI decreased with the number of reflux episodes when there was association, and remained constant and below 40% when there was not. The standard deviation was no higher than 40% and decreased with the reflux or symptom rates, and more sharply with the monitoring time, reaching approximately 0% for 50 days. A window length matching the characteristic reflux-symptom lag maximized the overall BSI and minimized its dispersion. Twenty-four hour and 96-h monitorings allowed detecting association ratios of 50% and 25%, respectively.
CONCLUSIONS & INFERENCES: The BSI is a simple and reliable index for the evaluation of symptom association that considers all the parameters under analysis. Defining an appropriate cut-off value, the BSI can provide a measure of probability and strength of association simultaneously.
胃食管反流症状关联的评估是一个悬而未决的问题。科学文献报告了重要的缺陷，临床医生也在呼吁采用新的方法。本文提供了一种评估症状关联的最佳方法，即二项式症状指数（BSI）。
本文提出了 BSI 的数学描述，用于研究关联和因果关系。使用蒙特卡罗模型模拟了总共 n = 850000 名患者，进行了双向灵敏度分析。通过对具有相同反流率、症状率、关联比、关联窗口和监测时间的 5000 名患者组进行评估，计算了 BSI 的平均值和标准差，以对比它们对估计值的影响。
当存在关联时，BSI 随反流事件次数的增加而降低，当不存在关联时，BSI 保持恒定且低于 40%。标准差不高于 40%，且随反流或症状率的降低而降低，随监测时间的延长而降低更为明显，在 50 天时约为 0%。与特征性反流-症状滞后相匹配的窗口长度可使整体 BSI 最大化，并使离散度最小化。24 小时和 96 小时监测可分别检测到 50%和 25%的关联比。
BSI 是一种简单可靠的评估症状关联的指标，考虑了所有分析中的参数。定义适当的截断值，BSI 可以同时提供关联的概率和强度的衡量。
