Associations between environmental exposures and asthma control and exacerbations in young children: a systematic review

Juan Carlos Ivancevich Thursday, 20 February 2014 18:08
BMJ Open 2014;4:e003827 doi:10.1136/bmjopen-2013-003827


Objective To complete a systematic review of the literature describing associations between all environmental exposures and asthma symptoms and exacerbations in children up to mean age of 9 years.
Design Systematic review.
Setting Reference lists of identified studies and reviews were searched for all articles published until November 2013 in electronic databases (MEDLINE, EMBASE, CINAHL, Cochrane Controls Trials Register).
Participants Studies were selected which examined a link between exposure to environmental factors and asthma symptoms and exacerbations where the study participants were children with a mean age of ⩽9 years.
Primary and secondary outcome measures Indices of asthma symptoms, control and exacerbations.
Results A total of 27 studies were identified including eight where inhaled allergens and four where environmental tobacco smoke (ETS) were the exposures of interest. There was evidence that exposure to allergen, ETS, poor air quality and unflued heaters had a modest magnitude of effect (ORs between 2 and 3). There was also evidence of interactions observed between exposures such as allergen and ETS.
Conclusions Exposure to inhaled allergens, ETS, unflued heaters and poor air quality has an important effect on exacerbations in young children with asthma and should be minimised or, ideally, avoided. Better understanding of the effect of exposure to damp housing, air conditioning and dietary factors plus interactions between environmental exposures associated with exacerbations is required.

This Article

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Pregnant moms' colds may cause asthma in offspring

Super User Wednesday, 05 February 2014 15:55

Research indicates that the more colds and other viral infections a woman has during pregnancy, the more likely her child is to have asthma. The more colds and other viral infections a woman has during pregnancy, the more likely her child is to have asthma, researchers report. The new study included 513 pregnant women in Germany and their 526 babies. The mothers completed questionnaires during pregnancy, when the children were 3 months old, 12 months old and every year until the children reached age 5. The researchers concluded that a mother's level of exposure to viral infections and bacteria during pregnancy affect the environment in the womb, and therefore the baby's risk of developing asthma and allergies in childhood. "In addition, these same children that had early exposure to allergens, such as house dust and pet dander, had increased odds of becoming sensitized by age 5," journal deputy editor Dr Mitch Grayson said in a journal news release. Children affected before birth: "When dust mites from the mother and child's mattresses were examined, children with high dust mite exposure yet low bacteria exposure were more likely to be allergic to dust mites than those with low mite exposure and high bacteria contact," he added. Of the families in the study, 61% had a parent with asthma, hay fever or eczema. The study is published in the February issue of the Annals of Allergy, Asthma and Immunology: Sabina Illi, Juliane Weber, Anne Zutavern, Jon Genuneit, Rudolf Schierl, Christine Strunz-Lehner, Erika von Mutius. Perinatal influences on the development of asthma and atopy in childhood. Annals of Allergy, Asthma & Immunology Volume 112, Issue 2 , Pages 132-139.e1, February 2014

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Inhaled Corticosteroids and the Risk of Pneumonia in people with Asthma: A case control study

Super User Saturday, 01 February 2014 15:35

Abstract: Background: In clinical trials the use of inhaled corticosteroids is associated with an increased risk of pneumonia in people with chronic obstructive pulmonary disease but whether the same is true for people with asthma is not known. Methods: Using primary care data from The Health Improvement Network we identified people with asthma and from this cohort we identified cases with pneumonia/ lower respiratory tract infection, and age and sex matched controls. Conditional logistic regression was used to determine the association between the dose and type of inhaled corticosteroid and risk of pneumonia or LRTI. Results: There was a dose response relationship between strength of dose of inhaled corticosteroid and risk of pneumonia or lower respiratory tract infection (p-trend <0∙001), such that after adjusting for confounders people receiving the highest strength of inhaled corticosteroid (≥1000mcg) had a 2.04 (95% CI 1∙59 to 2∙64) increased risk of pneumonia or lower respiratory infection when compared to people with asthma who did not have a prescription for inhaled corticosteroids within the previous 90 days. Conclusion: People with asthma receiving inhaled corticosteroids are at an increased risk of pneumonia or lower respiratory infection with people receiving higher doses at greater risk. Pneumonia should be considered as a possible side effect of inhaled corticosteroids and the lowest dose of inhaled corticosteroids possible should be used in the management of asthma. McKeever T, Harrison TW, Hubbard R, Shaw D. Inhaled Corticosteroids And The Risk Of Pneumonia In People With Asthma: A Case Control Study Chest. 2013;144(6):1788-1794. doi:10.1378/chest.13-0871

Evaluation of the Modified Asthma Predictive Index in High-Risk Preschool Children

Juan Carlos Ivancevich Monday, 03 February 2014 12:17

Background: Prediction of subsequent school-age asthma during the preschool years has proven challenging. Objective To confirm in a post hoc analysis the predictive ability of the modified Asthma Predictive Index (mAPI) in a high-risk cohort and a theoretical unselected population. We also tested a potential mAPI modification with a 2-wheezing episode requirement (m2API) in the same populations. Methods Subjects (n = 289) with a family history of allergy and/or asthma were used to predict asthma at age 6, 8, and 11 years with the use of characteristics collected during the first 3 years of life. The mAPI and the m2API were tested for predictive value. Results For the mAPI and m2API, school-age asthma prediction improved from 1 to 3 years of age. The mAPI had high predictive value after a positive test (positive likelihood ratio ranging from 4.9 to 55) for asthma development at years 6, 8, and 11. Lowering the number of wheezing episodes to 2 (m2API) lowered the predictive value after a positive test (positive likelihood ratio ranging from 1.91 to 13.1) without meaningfully improving the predictive value of a negative test. Posttest probabilities for a positive mAPI reached 72% and 90% in unselected and high-risk populations, respectively. Conclusions In a high-risk cohort, a positive mAPI greatly increased future asthma probability (eg, 30% pretest probability to 90% posttest probability) and is a preferred predictive test to the m2API. With its more favorable positive posttest probability, the mAPI can aid clinical decision making in assessing future asthma risk for preschool-age children. Timothy S. Chang, Robert F. Lemanske, Theresa W. Guilbert, James E. Gern, Michael H. Coen, Michael D. Evans, Ronald E. Gangnon, C. David Page, Daniel J. Jackson.Evaluation of the Modified Asthma Predictive Index in High-Risk Preschool Children The Journal of Allergy and Clinical Immunology: In Practice - March 2013 (Vol. 1, Issue 2, Pages 152-156, DOI: 10.1016/j.jaip.2012.10.008) Full text.

Cost-effectiveness of primary prevention of paediatric asthma: a decision-analytic model

Juan Carlos Ivancevich Friday, 31 January 2014 15:35

Abstract - Background: Many children stand to benefit from being asthma-free for life with primary (i.e., prenatally started) prevention addressing one environmental exposure in a unifaceted (UF) approach or at least two in a multifaceted (MF) approach. We assessed the cost-effectiveness of primary prevention programmes for Dutch children in a decision-analytic framework. Methods A decision-analytic tree model analysing healthcare costs and asthma cases prevented was developed to compare usual care (UC) with two UF and three MF programmes on the primary prevention of asthma amongst children. Programmes were evaluated through incremental cost-effectiveness ratios and net monetary benefits. Decision and parameter uncertainty were subjected to value-of-information analyses. Results:The current UC and one of three MF programmes dominated the other alternatives. The MF programme was more costly but also more effective than UC at an incremental cost-effectiveness ratio of €8,209.20/additional asthma case prevented. The value of perfect information to reduce uncertainty was €291.6M at its lowest. Most of the uncertainty in the cost-effectiveness threshold was attributable to the probability and cost estimates for low-risk children. Conclusion: This study supports the feasibility of a structured programme that simultaneously addresses exposure to house dust mites, pet dander, environmental tobacco, and breast-feeding as a cost-effective alternative to UC in the primary prevention of asthma amongst children. G. Feljandro P. Ramos, Antoinette D. I. van Asselt, Sandra Kuiper, Johan L. Severens, Tanja Maas, Edward Dompeling, J. André Knottnerus, Onno C. P. van SchayckCost-effectiveness of primary prevention of paediatric asthma: a decision-analytic model. The European Journal of Health Economics October 2013. 

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Editor: Juan C. Ivancevich, MD

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