This review surveys the data on the increase in the prevalence of asthma in recent decades and finds evidence of a plateau in many Western countries. The authors examine the evidence of possible causal relations to factors such as air pollution, obesity, diet, and exposure to infections, antibiotics, and allergens, including exposures at very young ages. The most strongly supported preventive measure is the avoidance of passive and active exposure to smoke.

The asthma epidemic.

BackgroundRespiratory syncytial virus (RSV) infection is associated with subsequent recurrent wheeze. Observational studies cannot determine whether RSV infection is the cause of recurrent wheeze or the first indication of preexistent pulmonary vulnerability in preterm infants. The monoclonal antibody palivizumab has shown efficacy in preventing severe RSV infection in high-risk infants. MethodsIn the double-blind, placebo-controlled MAKI trial, we randomly assigned 429 otherwise healthy preterm infants born at a gestational age of 33 to 35 weeks to receive either monthly palivizumab injections (214 infants) or placebo (215 infants) during the RSV season. The prespecified primary outcome was the total number of parent-reported wheezing days in the first year of life. Nasopharyngeal swabs were taken during respiratory episodes for viral analysis. ResultsPalivizumab treatment resulted in a relative reduction of 61% (95% confidence interval, 56 to 65) in the total number of wheezing days during the first yea...

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Respiratory syncytial virus and recurrent wheeze in healthy preterm infants.

A mixture of neutral short-chain galactooligosaccharides (scGOS) and long-chain fructooligosaccharides (lcFOS) has been shown to reduce the incidence of atopic dermatitis (AD) and infectious episodes during the first 6 mo of life. This dual protection occurred through the intervention period. The present study evaluated if these protective effects were lasting beyond the intervention period. In a prospective, randomized, double-blind, placebo-controlled design, healthy term infants with a parental history of atopy were fed either a prebiotic-supplemented (8 g/L scGOS/lcFOS) or placebo-supplemented (8 g/L maltodextrin) hypoallergenic formula during the first 6 mo of life. Following this intervention period, blind follow-up continued until 2 y of life. Primary endpoints were cumulative incidence of allergic manifestations. Secondary endpoints were number of infectious episodes and growth. Of 152 participants, 134 infants (68 in placebo, 66 in intervention group) completed the follow-up. During this period, infants in the scGOS/lcFOS group had significantly lower incidence of allergic manifestations. Cumulative incidences for AD, recurrent wheezing, and allergic urticaria were higher in the placebo group, (27.9, 20.6, and 10.3%, respectively) than in the intervention group (13.6, 7.6, and 1.5%) (P < 0.05). Infants in the scGOS/lcFOS group had fewer episodes of physician-diagnosed overall and upper respiratory tract infections (P < 0.01), fever episodes (P < 0.00001), and fewer antibiotic prescriptions (P < 0.05). Growth was normal and similar in both groups. Early dietary intervention with oligosaccharide prebiotics has a protective effect against both allergic manifestations and infections. The observed dual protection lasting beyond the intervention period suggests that an immune modulating effect through the intestinal flora modification may be the principal mechanism of action.

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Early Dietary Intervention with a Mixture of Prebiotic Oligosaccharides Reduces the Incidence of Allergic Manifestations and Infections during the First Two Years of Life

Background: Allergic disorders are common in the UK. This study reviews recent UK time trends in the prevalence, morbidity and mortality for allergic disorders, excluding asthma.

Methods: A trend analysis was performed over recent decades of national, representative or repeat surveys, primary care consultations, prescriptions, hospital admissions, and mortality.

Results: Serial surveys showed that the prevalence of diagnosed allergic rhinitis and eczema in children have both trebled over the last three decades. While these long term trends were paralleled by the prevalence of disease symptoms, more recent symptom prevalence data suggest a decline. Similarly, GP consultation rates rose by 260% for hay fever and by 150% for eczema overall during the period 1971–91, but rates have stabilised over the past decade. Hospital admissions for eczema have been stable since 1995, and hospital admissions for allergic rhinitis have fallen to about 40% of their 1990 levels. Since 1990, admissions for anaphylaxis have increased by 700%, for food allergy by 500%, for urticaria by 100%, and for angio-oedema by 40%. Prescriptions issued for all types of allergy have increased since 1991.

Conclusions: The prevalence and healthcare usage for eczema and hay fever have increased substantially over recent decades, but may now be stabilising or even falling. In contrast, admissions for some systemic allergic diseases have risen sharply in the last decade which may indicate a rising incidence of these conditions. Although changes in treatment and other healthcare factors may have contributed to these trends, there may also be a change in the aetiology of allergic disease in the UK.

https://thorax.bmj.com/content/thoraxjnl/62/1/91.full.pdf

Time trends in allergic disorders in the UK

The prevalence of atopic eczema has been found to have increased greatly in some parts of the world. Building on a systematic review of global disease trends in asthma, our objective was to study trends in incidence and prevalence of atopic eczema. Disease trends are important for health service planning and for generating hypotheses regarding the aetiology of chronic disorders. We conducted a systematic search for high quality reports of cohort, repeated cross-sectional and routine healthcare database-based studies in seven electronic databases. Studies were required to report on at least two measures of the incidence and/or prevalence of atopic eczema between 1990 and 2010 and needed to use comparable methods at all assessment points. We retrieved 2,464 citations, from which we included 69 reports. Assessing global trends was complicated by the use of a range of outcome measures across studies and possible changes in diagnostic criteria over time. Notwithstanding these difficulties, there was evidence suggesting that the prevalence of atopic eczema was increasing in Africa, eastern Asia, western Europe and parts of northern Europe (i.e. the UK). No clear trends were identified in other regions. There was inadequate study coverage worldwide, particularly for repeated measures of atopic eczema incidence. Further epidemiological work is needed to investigate trends in what is now one of the most common long-term disorders globally. A range of relevant measures of incidence and prevalence, careful use of definitions and description of diagnostic criteria, improved study design, more comprehensive reporting and appropriate interpretation of these data are all essential to ensure that this important field of epidemiological enquiry progresses in a scientifically robust manner.

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Investigating international time trends in the incidence and prevalence of atopic eczema 1990-2010: a systematic review of epidemiological studies.

Are all wheezing disorders in very young (preschool) children increasing in prevalence

Institution and country of all co-authors (1) Swiss Paediatric Respiratory Research Group, Department of Social and Preventive Medicine, University of Berne, Switzerland (2) The Leicester Children's Asthma Centre, Division of Child Health, Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, LE2 7LX, UK (3) Specialist Community Child Health Services, Leicester City PCT, Bridge Park Plaza, Thurmaston, Leicester, LE4 8PQ, UK

Cohort Profile: The Leicester Respiratory Cohorts

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140673601062900.pdf

Anthony Davis

Papers

Are all wheezing disorders in very young (preschool) children increasing in prevalence

Cohort Profile: The Leicester Respiratory Cohorts

Vaccinations as risk factors for wheezing disorders

Cohort Profile: The Leicester Respiratory