Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
Headache. 2013 Apr;53(4):636-43. doi: 10.1111/head.12075. Epub 2013 Mar 27.
In this study, we set out to determine whether individual headache sufferers can learn about the potency of their headache triggers (causes) using only natural experimentation.
Headache patients naturally use the covariation of the presence-absence of triggers with headache attacks to assess the potency of triggers. The validity of this natural experimentation has never been investigated. A companion study has proposed 3 assumptions that are important for assigning causal status to triggers. This manuscript examines one of these assumptions, constancy in trigger presentation, using real-world conditions.
The similarity of day-to-day weather conditions over 4 years, as well as the similarity of ovarian hormones and perceived stress over a median of 89 days in 9 regularly cycling headache sufferers, was examined using several available time series. An arbitrary threshold of 90% similarity using Gower's index identified similar days for comparison.
The day-to-day variability in just these 3 headache triggers is substantial enough that finding 2 naturally similar days for which to contrast the effect of a fourth trigger (eg, drinking wine vs not drinking wine) will only infrequently occur. Fluctuations in weather patterns resulted in a median of 2.3 days each year that were similar (range 0-27.4). Considering fluctuations in stress patterns and ovarian hormones, only 1.5 days/month (95% confidence interval 1.2-2.9) and 2.0 days/month (95% confidence interval 1.9-2.2), respectively, met our threshold for similarity.
Although assessing the personal causes of headache is an age-old endeavor, the great many candidate triggers exhibit variability that may prevent sound conclusions without assistance from formal experimentation or statistical balancing.
本研究旨在确定个体头痛患者是否仅通过自然实验就能了解头痛触发因素（病因）的效力。
头痛患者自然会利用触发因素与头痛发作的存在-缺失的共变来评估触发因素的效力。这种自然实验的有效性从未被研究过。一项伴随研究提出了 3 个对于将触发因素归因于因果关系非常重要的假设。本手稿检验了其中一个假设，即触发因素呈现的恒定性，使用的是真实条件。
使用几种可用的时间序列，检查了 4 年来天气条件的日常相似性，以及 9 名定期周期性头痛患者中卵巢激素和感知压力的中位数为 89 天的相似性。使用 Gower 指数的 90%相似性任意阈值确定了相似的日子进行比较。
仅这 3 个头痛触发因素的日常可变性就足够大，以至于要找到 2 个自然相似的日子来对比第四个触发因素（例如，饮酒与不饮酒）的效果，这种情况很少发生。天气模式的波动导致每年平均有 2.3 天相似（范围 0-27.4）。考虑到压力模式和卵巢激素的波动，只有每月 1.5 天（95%置信区间 1.2-2.9）和 2.0 天（95%置信区间 1.9-2.2）符合我们的相似性阈值。
尽管评估头痛的个人病因是一项古老的努力，但由于大量候选触发因素存在可变性，如果没有正式实验或统计平衡的帮助，可能无法得出合理的结论。
