Wypych-Ślusarska Agata, Krupa-Kotara Karolina, Oleksiuk Klaudia, Głogowska-Ligus Joanna, Słowiński Jerzy
Department of Epidemiology, Faculty of Public Health in Bytom, Medical University of Silesia, 40-055 Katowice, Poland.
Children (Basel). 2024 Aug 5;11(8):941. doi: 10.3390/children11080941.
Some epidemiological studies suggest that early exposure to animal allergens during infancy reduces the risk of bronchial asthma in school-age children. However, the observed associations in some cases may be an effect of the study used (epidemiological observational studies, especially a cross-sectional study) and indicate reverse causality.
This study aimed to determine the association between exposure to animal allergens and the prevalence of respiratory diseases, including bronchial asthma, considering the potential impact of reverse causality on the observed relationships.
An analysis of data from a cross-sectional epidemiological study conducted in 2020 involving 3237 primary school students aged 7-15 years in the Silesian Province (Southern Poland) was carried out. The parents of students completed a questionnaire based on The International Study on Asthma and Allergies in Childhood (ISAAC). The relationship between the occurrence of chronic cough, wheezing, and dyspnea in the last 12 months, night waking due to dyspnea, and asthma in the presence of pets was assessed. Exposure to animal allergens was determined by answering the question, "Are there any furry or feathered animals in the home?" with three response options: "yes; they have been in the past; no" (Scenario 1). For the analyses and to reveal a potential reverse causality effect, the last two response categories regarding pet ownership were combined to form a "no" category in Scenario 2, and the first two answers were combined into a "yes" category in Scenario 3. A chi-square test was used to assess the relationship between variables, and a statistical significance level of < 0.05 was adopted.
Chronic cough affected 9.5% of children, wheezing in the last 12 months-9.2%, night waking due to dyspnea-5.8%, dyspnea in the last 12 months-4.8%, bronchial asthma-9.2%. Analysis considering the category of having or not having pets (yes vs. no) showed that bronchial asthma was statistically significantly more common in children who did not have pets at home (10.9% vs. 7.9%, = 0.002). A similar situation was observed for wheezing in the past 12 months (10.7% vs. 8.1%; = 0.01) and nocturnal awakening due to dyspnea (6.8% vs. 5.1%, = 0.03). No statistically significant differences were observed for the other symptoms. Analysis by time of pet ownership (a. present; b. present but in the past; c. not present) highlighted similar relationships. Asthma (a. 7.7% vs. b. 13.4% vs. c. 7.7%; = 0.004), wheezing in the past 12 months (a. 8.1% vs. b. 8.9% vs. c. 10.9%, = 0.03) and night waking (a. 5.0% vs. b. 4.5% vs. c. 7.1%; = 0.04) were more common in children without pets and those who had owned pets in the past. The highest proportion of children with asthma was in homes where pets were present in the past.
Analyses indicating a relationship between a higher prevalence of asthma and some respiratory symptoms, and the absence of pets cannot be considered as a casual association. The analysis conducted did not reveal a reverse causality effect. The results of observational epidemiological studies, especially a cross-sectional study, should always be interpreted with caution, considering possible distortions and conclusions drawn.
一些流行病学研究表明，婴儿期早期接触动物过敏原可降低学龄儿童患支气管哮喘的风险。然而，在某些情况下观察到的关联可能是所用研究方法（流行病学观察性研究，尤其是横断面研究）的结果，并提示存在反向因果关系。
本研究旨在确定接触动物过敏原与呼吸道疾病（包括支气管哮喘）患病率之间的关联，同时考虑反向因果关系对观察到的关系的潜在影响。
对2020年在波兰南部西里西亚省开展的一项横断面流行病学研究的数据进行分析，该研究涉及3237名7 - 15岁的小学生。学生家长根据儿童哮喘和过敏国际研究（ISAAC）完成了一份问卷。评估了过去12个月内慢性咳嗽、喘息、呼吸困难的发生情况，因呼吸困难导致的夜间醒来情况，以及家中有宠物时哮喘的发生情况。通过回答“家中是否有带毛或带羽毛的动物？”这一问题来确定接触动物过敏原的情况，有三个回答选项：“是；过去有过；否”（情况1）。为了进行分析并揭示潜在的反向因果关系效应，在情况2中，将关于宠物饲养的最后两个回答类别合并为一个“否”类别，在情况3中，将前两个回答合并为一个“是”类别。使用卡方检验评估变量之间的关系，采用的统计显著性水平为<0.05。
慢性咳嗽影响了9.5%的儿童，过去12个月内喘息的儿童占9.2%，因呼吸困难导致夜间醒来的儿童占5.8%，过去12个月内出现呼吸困难的儿童占4.8%，支气管哮喘患儿占9.2%。考虑家中是否有宠物（是与否）这一分类的分析表明，家中没有宠物的儿童患支气管哮喘在统计学上显著更常见（10.9%对7.9%，P = 0.002）。过去12个月内喘息情况（10.7%对8.1%；P = 0.01）以及因呼吸困难导致的夜间觉醒情况（6.8%对5.1%，P = 0.03）也观察到类似情况。其他症状未观察到统计学上的显著差异。按宠物饲养时间分析（a. 现在有；b. 现在没有但过去有；c. 现在没有）突出了类似的关系。哮喘（a. 7.7%对b. 13.4%对c. 7.7%；P = 0.004）、过去12个月内喘息（a. 8.1%对b. 8.9%对c. 10.9%，P = 0.03）和夜间醒来（a. 5.0%对b. 4.5%对c. 7.1%；P = 0.04）在没有宠物以及过去养过宠物的儿童中更常见。哮喘儿童比例最高的是过去家中有宠物的情况。
表明哮喘和一些呼吸道症状患病率较高与没有宠物之间存在关联的分析不能被视为因果关系。所进行的分析未揭示反向因果关系效应。观察性流行病学研究的结果，尤其是横断面研究的结果，在考虑可能的偏差和得出的结论时应始终谨慎解释。
