乙酰甲胆碱激发试验的季节性变化
2010/02/22
背景：由于某些影响支气管高反应性（BHR）的变量强度随季节而变化，因此乙酰甲胆碱激发试验（MCT）阳性百分比理论上也存在季节性变化。本试验旨在疑似哮喘的年轻成人中研究MCT的季节性差异。
方法：回顾性评价过去五年MCT的检测次数及相应的阳性比率，比较不同季节MCT阳性检测率差异。
结果：研究期间共有645例患者（平均21.4±2.3岁）接受MCT。209次（34.2％）MCTs在冬季进行，显著高于其他季节。163例（25.2％）患者MCT阳性（定义为PC20< 16 mg/ml）。MCT阳性比例呈现明显的季节趋势（P<0.0001，卡方检验），与夏季相比（13.4%），阳性率在冬季和春季显著增加，分别为32.2%和32.4%。
结论：本研究显示，年轻成人中BHR的发生率和MCT检测次数存在显著的季节性差异。上述结果可能反应了外部刺激的季节性差异，而这些外部刺激参与了BHR的病理生理学过程（如过敏原增加，呼吸道感染增加等）。我们认为，将MCT阳性作为BHR或哮喘的预测因素需要考虑MCT的季节性差异。
（林江涛 审校）
J Asthma. 2009 Nov;46(9):951-954.
Seasonal variability of the methacholine challenge test.
Fruchter O, Yigla M.
Division of Pulmonary Medicine, Rambam Health Care Campus, Technion, Institute of Technology, Haifa, Israel.
BACKGROUND: Since the intensity of some variables that influence bronchial hyper-responsiveness (BHR) varies across different seasons of the year, the percentage of positive metacholine challenge test (MCT) is theoretically subjected to seasonal variation. This study has looked at the seasonal variability of MCT among young adults with suspected asthma.
METHODS: The number of MCT performed and its corresponding proportion of positive results were retrospectively evaluated and compared for different seasons over a 5-year period.
RESULTS: Overall 645 subjects (mean age 21.4 +/- 2.3 yr) underwent MCT during the study period. Two-hundred nine MCTs (34.2%) were performed in the winter, significantly higher when compared to any other season of the year. Positive MCT (defined as PC(20) < 16 mg/mL) was noted in 163 patients (25.2%). The proportion of positive MCTs has shown significant seasonal trend, (p < 0.0001, chi-square test for trend), it was significantly higher in the winter and in the spring (32.2% and 32.4%, respectively) when compared with the summer (13.4%).
CONCLUSIONS: This study showed a significant seasonal variability for both pattern of referral to MCT and the seasonal prevalence of BHR young adults. These findings probably reflect seasonal variation in the intensity of external stimuli that involve in the pathogenesis of BHR, such as allergens burden and respiratory tract infections across the year. We suggest that interpretation of a positive MCT as predictive of BHR and of asthma should take into account the observed seasonal variability of the test.
J Asthma. 2009 Nov;46(9):951-4.
方法：回顾性评价过去五年MCT的检测次数及相应的阳性比率，比较不同季节MCT阳性检测率差异。
结果：研究期间共有645例患者（平均21.4±2.3岁）接受MCT。209次（34.2％）MCTs在冬季进行，显著高于其他季节。163例（25.2％）患者MCT阳性（定义为PC20< 16 mg/ml）。MCT阳性比例呈现明显的季节趋势（P<0.0001，卡方检验），与夏季相比（13.4%），阳性率在冬季和春季显著增加，分别为32.2%和32.4%。
结论：本研究显示，年轻成人中BHR的发生率和MCT检测次数存在显著的季节性差异。上述结果可能反应了外部刺激的季节性差异，而这些外部刺激参与了BHR的病理生理学过程（如过敏原增加，呼吸道感染增加等）。我们认为，将MCT阳性作为BHR或哮喘的预测因素需要考虑MCT的季节性差异。
（林江涛 审校）
J Asthma. 2009 Nov;46(9):951-954.
Seasonal variability of the methacholine challenge test.
Fruchter O, Yigla M.
Division of Pulmonary Medicine, Rambam Health Care Campus, Technion, Institute of Technology, Haifa, Israel.
BACKGROUND: Since the intensity of some variables that influence bronchial hyper-responsiveness (BHR) varies across different seasons of the year, the percentage of positive metacholine challenge test (MCT) is theoretically subjected to seasonal variation. This study has looked at the seasonal variability of MCT among young adults with suspected asthma.
METHODS: The number of MCT performed and its corresponding proportion of positive results were retrospectively evaluated and compared for different seasons over a 5-year period.
RESULTS: Overall 645 subjects (mean age 21.4 +/- 2.3 yr) underwent MCT during the study period. Two-hundred nine MCTs (34.2%) were performed in the winter, significantly higher when compared to any other season of the year. Positive MCT (defined as PC(20) < 16 mg/mL) was noted in 163 patients (25.2%). The proportion of positive MCTs has shown significant seasonal trend, (p < 0.0001, chi-square test for trend), it was significantly higher in the winter and in the spring (32.2% and 32.4%, respectively) when compared with the summer (13.4%).
CONCLUSIONS: This study showed a significant seasonal variability for both pattern of referral to MCT and the seasonal prevalence of BHR young adults. These findings probably reflect seasonal variation in the intensity of external stimuli that involve in the pathogenesis of BHR, such as allergens burden and respiratory tract infections across the year. We suggest that interpretation of a positive MCT as predictive of BHR and of asthma should take into account the observed seasonal variability of the test.
J Asthma. 2009 Nov;46(9):951-4.
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