Tanja Maas

The PREVASC study: the clinical effect of a multifaceted educational intervention to prevent childhood asthma

As asthma is the most common chronic disease in childhood, much attention is directed towards primary prevention. Here, the clinical effectiveness of a multifaceted educational prevention was studied. A total of 476 high-risk children were recruited during the prenatal period by general practitioners and randomised to either: 1) a control group, receiving usual care; or 2) an intervention group in which families received instruction from nurses on how to reduce exposure of newborns to mite, pet and food allergens, and passive smoking. A total of 443 infants were followed-up for 2u2005yrs. At 2u2005yrs of age, the intervention group (nu200a=u200a222) had less asthma-like symptoms, including wheezing, shortness of breath and night-time cough, than the control group (nu200a=u200a221). No significant differences in total and specific immunoglobulin E were found between the groups. During the first 2u2005yrs of life, the incidence of asthma-like symptoms was similar in both groups; however, subanalysis revealed a significant reduction in the female, but not in the male, intervention group. In conclusion, the intervention used in this study was not effective in reducing asthma-like symptoms in high-risk children during the first 2u2005yrs of life, although it was modestly effective at 2u2005yrs. Follow-up is necessary to confirm whether the intervention can actually prevent the development of asthma.

Mono and multifaceted inhalant and/or food allergen reduction interventions for preventing asthma in children at high risk of developing asthma.

BACKGROUNDnAllergen exposure is one of the environmental factors seemingly associated with the development of asthma. If asthma is a multi-factorial disease, it is hypothesised that prevention might only prove effective if most or all relevant environmental factors are simultaneously avoided.nnnOBJECTIVESnTo assess effect(s) of monofaceted and multifaceted interventions compared with control interventions in preventing asthma and asthma symptoms in high risk children.nnnSEARCH STRATEGYnWe searched the Cochrane Airways Trials Register (December 2008).nnnSELECTION CRITERIAnRandomised controlled trials of allergen exposure reduction for the primary prevention of asthma in children. Interventions were multifaceted (reducing exposure to both inhalant and food allergens) or monofaceted (reducing exposure to either inhalant or food allergens) Follow up had to be from birth (or during pregnancy) up to a minimum of two years of age.nnnDATA COLLECTION AND ANALYSISnWe included in the analysis studies assessing the primary outcome (current diagnosis: asthma) and/or one of the secondary outcomes (current respiratory symptoms: wheezing, nocturnal coughing and dyspnoea). We pooled multifaceted and monofaceted intervention trials separately. We made an indirect comparison of their effects using tests for interaction to calculate relative odds ratios.nnnMAIN RESULTSnWe included three multifaceted and six monofaceted intervention studies (3271 children). Physician diagnosed asthma in children less than five years, and asthma as defined by respiratory symptoms and lung function criteria in children aged five years and older, both favoured treatment with a multifaceted intervention compared to usual care (< 5 years: odds ratio (OR) 0.72, 95% confidence interval (CI) 0.54 to 0.96, and > 5 years: OR 0.52, 95% CI 0.32 to 0.85). However, there was no significant difference in outcome between monofaceted intervention and control interventions (< 5 years: OR 1.12, 95% CI 0.76 to 1.64, and > 5 years: OR 0.83, 95% CI 0.59 to 1.16). Indirect comparison between these treatments did not demonstrate a significant difference between multiple interventions and mono-interventions in reducing the frequency of asthma diagnosis in children under five years (relative OR 0.64 (95% CI 0.40 to 1.04, P = 0.07) or five years and older (relative OR 0.63, 95% CI 0.35 to 1.13, P = 0.12). There was also no significant difference between either mono- and multifaceted intervention and control in reducing the likelihood of symptoms of nocturnal coughing at follow up. Wheezing, however, showed a significant difference between multifaceted and mono-interventions (relative OR 0.59, 95% CI 0.35 to 0.99, P = 0.04), but the significance was lost when data on treatment only was analysed.nnnAUTHORS CONCLUSIONSnThe available evidence suggests that the reduction of exposure to multiple allergens compared to usual care reduces the likelihood of a current diagnosis of asthma in children (at ages < 5 years and 5 years and older). Mono-intervention studies have not produced effects which are statistically significant compared with control. In children who are at risk of developing childhood asthma, multifaceted interventions, characterised by dietary allergen reduction and environmental remediation, reduce the odds of a physician diagnosis of asthma later in childhood by half. This translates to a number needed to treat (NNT) of 17. The effect of multi-faceted interventions on parent reported wheeze was inconsistent and had no significant impact on nocturnal coughing or dyspnoea. Data from monofaceted intervention exposed children studies were not significantly different from those of control groups for all outcomes. There remains uncertainty as to whether multiple interventions are more effective than mono-component interventions. The comparisons made were indirect, making the conclusions drawn uncertain. To our knowledge there are no ongoing studies in which both intervention strategies are randomly compared. The findings, however, warrant further direct comparison between multiple- and monofaceted interventions aimed at reducing the prevalence of asthma in children.

The primary prevention of asthma in children study: Design of a multifaceted prevention program

The PREVASC study addresses the primary prevention of asthma in infants and small children. The objective of this study is to investigate whether a multifaceted prenatally started intervention strategy in high‐risk infants leads to a decrease in the occurrence of (severe) asthma and whether a refinement of the prevention strategy leads to an increase in the adherence to the prevention program. The primary prevention program includes house dust mite impermeable bed coverings, education on breast feeding, hypoallergenic feeding, timing of introduction of solid food and smoking cessation. A total of 888 infants were prenatally included. By the time of inclusion the mothers were 3–7u2003months pregnant. About 27 infants were excluded from the study and 18 dropped out. Of the remaining 843 infants 535 had a first‐degree familial predisposition of asthma (high‐risk group), whereas a reference group of 308 (162 boys) infants was not predisposed for asthma in the first‐degree (low‐risk group). To evaluate the (cost‐)effectiveness of the preventive intervention, 222 (118 boys) infants of the high‐risk group allocated to the intervention group and 221 (112 boys) allocated to a control group are followed up. The low‐risk infants served as controls to evaluate the predictive value of high risk (first‐degree familial predisposition of asthma). The infants are followed from the prenatal stage until they reach the age of 6u2003yr. The remaining 92 high‐risk infants were included in an optimized randomized‐clinical adherence trial (RCAT). Of these 92 infants, 45 (20 boys) were allocated to an intervention group and 47 (24 boys) to a control group. Until now all infants have been followed for at least 1u2003yr.

Compliance of asthmatic families with a primary prevention programme of asthma and effectiveness of measures to reduce inhalant allergens – a randomized trial

Background Compliance to and the effect of pre‐ and post‐natal exposure reduction measures to prevent asthma in high‐risk children from asthmatic families were studied.

Prevention of asthma in genetically susceptible children: a multifaceted intervention trial focussed on feasibility in general practice.

To cite this article: Maas T, Dompeling E, Muris JWM, Wesseling G, Knottnerus JA, van Schayck OCP. Prevention of asthma in genetically susceptible children: A multifaceted intervention trial focussed on feasibility in general practice. Pediatr Allergy Immunol 2011: 22: 794–802.

Gender-specific differences in the prevention of asthma-like symptoms in high-risk infants

The prevalence of asthma in children has increased in the last decades, and gender‐specific differences in asthma development have recently been suggested. The present study investigates whether gender differences are present in a population of young children (0–2u2003yr) with a high risk for the development of asthma on the basis of the presence of asthma in first‐degree relative(s). The study was performed on 222 children (118 boys, 104 girls) with a familial predisposition of asthma, which received standardized recommendations to reduce exposure to allergens (dust mite, pets and food allergens) and to passive smoking. Health outcome (wheezing episodes and shortness of breath) and compliance with allergen‐reducing measures were studied by means of multiple regression analyses. Boys suffered more from asthma‐like complaints than girls, as diagnosed by the general practitioner (32% vs. 18%, respectively, pu2003=u20030.023). Compliance with intervention measures was similar for boys and girls for most allergens, but food allergen reduction was better applied for girls: duration of exclusive breastfeeding was longer in girls (median 9u2003wk vs. 4u2003wk, pu2003=u20030.009). Further analysis showed that 4u2003wk of longer breastfeeding reduced the number of wheezing episodes and shortness of breath in boys by 19% and 15%, respectively, but not in girls, suggesting sex as an effect modifier in the relationship between breastfeeding and asthma‐like symptoms. The present findings indicate that application and effects of prevention strategies for children with a high risk for developing asthma might be gender‐specific and suggest a special importance of breastfeeding boys.

Environmental exposure reduction in high-risk newborns: where do we start?

BACKGROUNDnWhen analyzing the effect of environmental exposure reduction measures on asthma in high-risk children, one must know how far asthmatic families already have applied such measures, because this would affect the effectiveness and efficiency of interventions aimed at reducing environmental exposure.nnnOBJECTIVEnTo describe the room for improvement by asthmatic families in mite, pet, and food allergen reducing measures and in parental passive smoking and to determine the resulting levels of mite and pet allergens by the applied sanitation measures.nnnMETHODSnData were sampled by observation, weekly diary entries, and questionnaire when the infant was 6 months old and 1 year old. Dust samples were collected by vacuuming the living room floor and the parental and infant mattresses. Multiple logistic regression analyses were applied with the use of mattress encasing, having a smooth floor covering, having pets, exclusive breast-feeding and/or hypoallergenic formula during the infants first 6 months, and passive smoking as the dependent variables.nnnRESULTSnFrequencies of applied measures were as follows: having a smooth floor covering, 36%; daily house cleaning, 27%; use of parental and infant antimite mattress encasings, 13% and 9%, respectively; keeping no pets, 66%; no cows milk-based regular formula, 13%; no solid foods in the first 6 months of life, 28%; and abstinence of smoking by the mother prenatally, 89%; by the mother postnatally, 85%; and by her partner, 76%. Having a smooth floor covering and daily cleaning but not use of antimite mattress encasings resulted in significantly lower mite and pet allergen levels.nnnCONCLUSIONSnThere is (still) enough room for improvement to reduce exposure to inhalant and food allergens, especially by application of mattress encasings, exclusive breast-feeding and/or hypoallergenic formula feeding, and postponing the time until first solids are given.

Distribution of house dust mite allergen: comparing house dust mite allergen levels in dust samples collected from different sites on living room floors with smooth coverings.

Background: The distribution of house dust mite allergen (Der p1) in living rooms with smooth floor coverings, as measured in the middle compared with the border of the floor was investigated. It was hypothesized that activity causes displacement of Der p1, from the middle towards the border.

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

AbstractBackgroundnMany 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.MethodsA 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.ResultsThe 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.ConclusionThis 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.n

Intervenciones de reducción de alérgenos mono y multifacéticas para la prevención del asma en niños con alto riesgo de desarrollo de asma

artículo recibido: 07-12-2010 artículo aprobado para publicación: 07-12-2010 Criterios de selección Los ensayos controlados aleatorios de la reducción de la exposición a alérgenos para la prevención primaria del asma en niños. Las intervenciones fueron multifacéticas (reducen la exposición a los alérgenos, inhalados y alimentarios) o monofacéticas (reducen la exposición a alérgenos inhalados o alimentarios). El seguimiento tenía que ser desde el nacimiento (o durante el embarazo) hasta un mínimo de dos años de edad.