Smoke Exposure and Allergic Sensitisation in Children
Smoke Exposure and Allergic Sensitisation in Children
Background Environmental tobacco smoke (ETS) exposure in children is linked with the development of allergic asthma. However, its influence on allergic sensitisation in children has not been conclusively determined.
Objective To systematically review existing evidence of ETS exposure's impact on markers of allergic sensitisation in children.
Methods CENTRAL, MEDLINE and EMBASE databases were searched. Included studies assessed following markers of atopic sensitisation: total immunoglobulin E (tIgE) concentrations, at least one specific IgE (sIgE+), and positive skin-prick tests (SPTs+) in ETS-exposed and non-exposed children.
Results 8 studies on the influence of ETS on tIgE concentration (2603 patients), 6 studies on ETS and sIgE+ (9230 participants) and 14 papers on ETS and SPT (14 150 patients) met our inclusion criteria. ETS was shown to raise tIgE concentrations by 27.7 IU/mL (95% CI 7.8 to 47.7; I=58%; results based on 3 studies) and to increase the risk of atopic sensitisation, as assessed by sIgE+ (OR=1.12, 95%CI 1.00 to 1.25; I=54%; results based on 4 studies) and SPT+ (OR=1.15; 95% CI 1.04 to 1.28; I=0%; results based on 10 studies). In a subgroup analysis, this effect was most pronounced in children <7 years (preschoolers) by OR=1.20; (95% CI 1.05 to 1.38) and OR=1.30 (95% CI 1.05 to 1.61), (for sIgE+ and SPT+, respectively).
Conclusions Current analysis supports an association between ETS exposure in early childhood and the increased risk of allergic sensitisation. Subgroup meta-analyses demonstrate that younger children suffer the most from detrimental immunomodulating effects of ETS exposure. This study underscores ETS as an important but avoidable risk factor for the development of allergic disease in children.
Environmental tobacco smoke (ETS) in children is believed to be related to impaired lung function and an increased risk to allergy and asthma. According to a recent systematic review by Burke et al, ETS exposure increases the incidence of asthma in children by at least 20%. The development of asthma in those exposed to ETS during pregnancy and early childhood is attributed to increased sensitivity to allergens. However, the precise immune pathways driving this phenomenon are still under debate and available data from large cross-sectional and cohort studies are conflicting. The existing evidence on smoking and allergic sensitisation was summarised by Strachan and Cook in 1998 in a systematic review, however, their results suggest no conclusive association.
Over the last 15 years, evidence has been surfacing which demonstrates the effect of tobacco smoke on immune function in a variety of in vitro and animal models. The limited existing data on passive smoking and its direct effects on immune responses and respiratory health in children seem to confirm these observations. Therefore, our aim was to systematically review and update data from cross-sectional and cohort studies regarding the effect of ETS on serum total immunoglobulin E (tIgE) and specific IgE (sIgE) and skin-prick tests (SPTs), since they are easily assessable and objective markers of allergic sensitisation in children.
Abstract and Introduction
Abstract
Background Environmental tobacco smoke (ETS) exposure in children is linked with the development of allergic asthma. However, its influence on allergic sensitisation in children has not been conclusively determined.
Objective To systematically review existing evidence of ETS exposure's impact on markers of allergic sensitisation in children.
Methods CENTRAL, MEDLINE and EMBASE databases were searched. Included studies assessed following markers of atopic sensitisation: total immunoglobulin E (tIgE) concentrations, at least one specific IgE (sIgE+), and positive skin-prick tests (SPTs+) in ETS-exposed and non-exposed children.
Results 8 studies on the influence of ETS on tIgE concentration (2603 patients), 6 studies on ETS and sIgE+ (9230 participants) and 14 papers on ETS and SPT (14 150 patients) met our inclusion criteria. ETS was shown to raise tIgE concentrations by 27.7 IU/mL (95% CI 7.8 to 47.7; I=58%; results based on 3 studies) and to increase the risk of atopic sensitisation, as assessed by sIgE+ (OR=1.12, 95%CI 1.00 to 1.25; I=54%; results based on 4 studies) and SPT+ (OR=1.15; 95% CI 1.04 to 1.28; I=0%; results based on 10 studies). In a subgroup analysis, this effect was most pronounced in children <7 years (preschoolers) by OR=1.20; (95% CI 1.05 to 1.38) and OR=1.30 (95% CI 1.05 to 1.61), (for sIgE+ and SPT+, respectively).
Conclusions Current analysis supports an association between ETS exposure in early childhood and the increased risk of allergic sensitisation. Subgroup meta-analyses demonstrate that younger children suffer the most from detrimental immunomodulating effects of ETS exposure. This study underscores ETS as an important but avoidable risk factor for the development of allergic disease in children.
Introduction
Environmental tobacco smoke (ETS) in children is believed to be related to impaired lung function and an increased risk to allergy and asthma. According to a recent systematic review by Burke et al, ETS exposure increases the incidence of asthma in children by at least 20%. The development of asthma in those exposed to ETS during pregnancy and early childhood is attributed to increased sensitivity to allergens. However, the precise immune pathways driving this phenomenon are still under debate and available data from large cross-sectional and cohort studies are conflicting. The existing evidence on smoking and allergic sensitisation was summarised by Strachan and Cook in 1998 in a systematic review, however, their results suggest no conclusive association.
Over the last 15 years, evidence has been surfacing which demonstrates the effect of tobacco smoke on immune function in a variety of in vitro and animal models. The limited existing data on passive smoking and its direct effects on immune responses and respiratory health in children seem to confirm these observations. Therefore, our aim was to systematically review and update data from cross-sectional and cohort studies regarding the effect of ETS on serum total immunoglobulin E (tIgE) and specific IgE (sIgE) and skin-prick tests (SPTs), since they are easily assessable and objective markers of allergic sensitisation in children.
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