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

Ardura Garcia, Cristina, Garner, Paul ORCID: https://orcid.org/0000-0002-0607-6941 and Cooper, Philip J (2018) 'Is childhood wheeze and asthma in Latin America associated with poor hygiene and infection? A systematic review'. BMJ Open Respiratory Research, Vol 5, Issue 1.

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Abstract

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
Subjects:	QS Anatomy > QS 4 General works. Classify here works on regional anatomy WA Public Health > Health Problems of Special Population Groups > WA 320 Child Welfare. Child Health Services. WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries WF Respiratory System > Lungs > WF 600 Lungs WS Pediatrics > Diseases of Children and Adolescents > By System > WS 280 Respiratory system
Faculty: Department:	Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI):	https://doi.org/10.1136/bmjresp-2017-000249
Depositing User:	Stacy Murtagh
Date Deposited:	09 Mar 2018 13:08
Last Modified:	06 Sep 2019 10:16
URI:	https://archive.lstmed.ac.uk/id/eprint/8329

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