Ardura-Garcia Cristina, Garner Paul, Cooper Philip J
Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.
Facultad de Ciencias Medicas, de la Salud y la Vida, Universidad Internacional del Ecuador, Quito, Ecuador.
BMJ Open Respir Res. 2018 Feb 22;5(1):e000249. doi: 10.1136/bmjresp-2017-000249. eCollection 2018.
High asthma prevalence in Latin-American cities is thought to be caused by poor hygiene and infections. This contradicts the widely accepted 'hygiene hypothesis' for asthma aetiology.
Systematic review of observational studies evaluating the association between poor hygiene exposures or infections and asthma/wheeze among Latin-American children aged 4-16 years. MEDLINE, EMBASE, LILACS and CINAHL electronic databases were searched following a predefined strategy to 18 December 2017. We quantified outcomes measured and reported, assessed risk of bias and tabulated the results.
Forty-five studies included: 6 cohort, 30 cross-sectional and 9 case-control studies. 26 cross-sectional studies were school-based surveys (14 of over 3000 children), whereas 5 case-control studies were hospital/health centre-based. Exposures measured and reported varied substantially between studies, and current wheeze was the most common outcome reported. Data showed selective reporting based on statistical significance (P value <0.05): 17/45 studies did not clearly describe the number of exposures measured and 15/45 studies reported on less than 50% of the exposures measured. Most exposures studied did not show an association with wheeze or asthma, except for a generally increased risk associated with acute respiratory infections in early life. Contradictory associations were observed frequently between different studies.
Selective reporting is common in observational studies exploring the association between environmental exposures and risk of wheeze/asthma. This, together with the use of different study outcomes (wheeze/asthma) associated with possibly distinct causal mechanisms, complicates inferences about the role of poor hygiene exposures and childhood infections in explaining asthma prevalence in Latin-American children.
拉丁美洲城市中哮喘的高患病率被认为是由卫生条件差和感染所致。这与被广泛接受的哮喘病因“卫生假说”相矛盾。
对评估4至16岁拉丁美洲儿童中卫生条件差的暴露或感染与哮喘/喘息之间关联的观察性研究进行系统综述。按照预先定义的策略检索MEDLINE、EMBASE、LILACS和CINAHL电子数据库至2017年12月18日。我们对测量和报告的结果进行了量化，评估了偏倚风险并列出了结果。
纳入45项研究：6项队列研究、30项横断面研究和9项病例对照研究。26项横断面研究是基于学校的调查（其中14项调查对象超过3000名儿童），而5项病例对照研究是基于医院/健康中心的。不同研究中测量和报告的暴露差异很大，当前喘息是报告的最常见结果。数据显示存在基于统计学显著性（P值<0.05）的选择性报告：17/45项研究未清楚描述所测量的暴露数量，15/45项研究报告的暴露不足所测量暴露的50%。除了生命早期急性呼吸道感染通常会增加风险外，大多数所研究的暴露与喘息或哮喘无关联。不同研究之间经常观察到相互矛盾的关联。
在探索环境暴露与喘息/哮喘风险之间关联的观察性研究中，选择性报告很常见。这与使用可能具有不同因果机制的不同研究结果（喘息/哮喘）一起，使得关于卫生条件差的暴露和儿童期感染在解释拉丁美洲儿童哮喘患病率中所起作用的推断变得复杂。
