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Is childhood wheeze and asthma in Latin America associated with poor hygiene and infection? A systematic review.

Ardura-Garcia, C; Garner, P; Cooper, PJ (2018) Is childhood wheeze and asthma in Latin America associated with poor hygiene and infection? A systematic review. BMJ Open Respir Res, 5 (1). e000249. ISSN 2052-4439 https://doi.org/10.1136/bmjresp-2017-000249
SGUL Authors: Cooper, Philip John

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Abstract

Introduction: 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. Methods: 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. 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. Conclusion: 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.

Item Type: Article
Additional Information: This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/ © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Keywords: Latin America, childhood asthma, hygiene hypothesis, infections, risk factors
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: BMJ Open Respir Res
ISSN: 2052-4439
Language: eng
Dates:
DateEvent
22 February 2018Published
Publisher License: Creative Commons: Attribution 4.0
Projects:
Project IDFunderFunder ID
099938/B/12/ZWellcome Trusthttp://dx.doi.org/10.13039/100004440
PubMed ID: 29531744
Go to PubMed abstract
URI: https://openaccess.sgul.ac.uk/id/eprint/109694
Publisher's version: https://doi.org/10.1136/bmjresp-2017-000249

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