Original article
Study of wheezing and its risk factors in the first year of life in the Province of Salamanca, Spain. The EISL Study

https://doi.org/10.1016/j.aller.2011.03.014Get rights and content

Summary

Objectives

To determine the prevalence of wheezing and its associated risk factors in infants in the first year of life in the province of Salamanca, Spain.

Methods

A multicentre, cross-sectional, descriptive epidemiological study was designed to evaluate a representative sample of 750 infants in the first year of life, born in the province of Salamanca between 1 June 2008 and 30 September 2009.

The study was based on a previously validated and standardised written questionnaire administered among the parents of those children seen for control at 12 months of age in any of the Primary Care centres in the province of Salamanca.

Results

The recorded wheezing rate was 32.3%. Feeding and sleep were seen to be affected in 46.3% and 80.9% of the wheezing children, respectively, and parent activity was also altered in 39.3% of the cases.

A relationship was found between wheezing and nursery attendance (OR: 1.66, 95% confidence interval [1.19–2.31]); weight at birth >3500 g (OR: 1.45 [1.02–2.06]); the presence of eczema at this age (OR: 2.72 [1.75–4.24]); exclusive breastfeeding for <3 months (OR: 1.33 [0.98–1.81]); and maternal smoking during the last three months of pregnancy (OR: 1.60 [0.96–2.68]).

The prevalence of recurrent wheezing (defined as three or more episodes) was 11.9%. Significant differences were observed with respect to nursery attendance (OR: 1.71 [1.08–2.72]), the presence of eczema at this age (OR: 2.55 [1.48–4.42]), a history of maternal asthma (OR: 2.19 [1.08–4.44]) and exclusive breastfeeding for <3 months (OR: 1.53 [0.98–2.38]).

Conclusions

In the province of Salamanca, one third of the infants studied suffered wheezing in the first year of life. Infants exclusively breastfed for less than three months; attending a nursery; having suffered eczema; or with an asthmatic mother showed significantly more wheezing than the rest. Wheezing proved recurrent in 11.9% of the cases.

Introduction

Wheezing is one of the most common causes of consultation in Paediatrics and of hospital admission in the first years of life. Recurrent wheezing has a significant impact upon the quality of life of patients and their families,1 with an important increase in healthcare resource utilisation and a high economical cost.

In 1992, the International Study of Asthma and Allergies in Childhood (ISAAC) made use of a simple methodology to conduct an epidemiological survey of such disorders.2 The ISAAC, in its phases I, II and III, has contributed the first large-scale data on asthma in children, offering very useful epidemiological information on this disease in large parts of the world, referring to children between 6 and 7 years of age and adolescents between 13 and 14 years of age.

While the prevalence and risk factors of asthma have been well studied in older children, and although different cohort studies conducted from birth have shed abundant light on the origin of wheezing in the first months and years of life,3 it is suspected that infants under one year of age show a high prevalence and incidence of wheezing episodes, and that there are different subgroups which express different inflammatory responses to a range of triggering agents. However, there are hardly any studies in this age segment. As a result, in recent years studies have been developed specifically addressing this infant population and focusing on viral aetiology4; allergic influences5; obstetric antecedents6; early exposure to certain allergens; environmental exposures7; or the use of certain drug substances during pregnancy.

It thus seems necessary to conduct broad multicentre studies involving a simple methodology, designed to determine and compare the prevalence of wheezing in nursing infants in the first year of life, and to evaluate the risk factors which might favour the presence of wheezing in this age range. Such studies moreover would pave the way for future research on the aetiology and evolution of the prevalence of the disorder in relation to different influencing genetic, environmental, lifestyle and medical care factors.

The present study has been carried out following the standardised method of the International study of wheezing in infants (EISL), based on a validated questionnaire8 and involving a very large sample of infants under one year of age in Latin America, Spain and the Netherlands.9

Section snippets

Materials and methods

The study was carried out using the aforementioned EISL questionnaire. Validation of the questionnaire in Spain was carried out,8 and its performance in terms of sensitivity, specificity and positive and negative predictive value is equivalent to that of other questionnaires in reference to objective testing.10 The methodology used in the EISL is based on that employed in the ISAAC in its phases I and III in older children.2 The mentioned questionnaire is the basis of the EISL, of which this

Results

A total of 750 children (394 males, 52.5%) with a mean weight at birth of 3.03 kg (SD = 0.77) and a height of 49.48 cm (SD = 3.46) were studied. Table 1 shows the descriptive results of the sample. Mean maternal age at the time of birth of the infant was 33.64 years (SD = 4.61).

The prevalence of wheezing was 32.3%. Of the 242 children with wheezing in the first year of life, 90 suffered a single episode; 68 had two episodes; and 89 suffered three or more episodes. The prevalence of RW was 11.9%.

A total

Discussion

Wheezing is very common in the first months of life. A recent study of families with a low socioeconomic level in Latin America11 has found that during the first year of life, 80.3% of all infants had suffered one or more wheezing episodes, 43.1% had recurrent wheezing (RW), and 13.3% had suffered pneumonia.

Although the magnitude of the problem is different in Europe, the ALSCAP study,12 carried out in the city of Bristol (United Kingdom), found 21.5% of the infants under six months of age to

Financial support

This project has been financed by the Gerencia Regional de Salud de Castilla y León, Dirección General de Desarrollo Sanitario, in the context of aids to “Research Projects in Biomedicine, Biotechnology and Health Sciences conducted in Primary Care”. GRS 287BA/08.

Conflict of interest

The authors have no conflict of interest to declare.

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  • Cited by (22)

    • Factors associated to recurrent wheezing in infants under one year of age in the province of Salamanca, Spain: Is intervention possible? A predictive model

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      A group of Spanish coordinators of the International Study of Asthma and Allergies in Childhood (ISAAC)16 developed the International Study on Wheezing in Nursing Infants (Estudio Internacional de Sibilancias en Lactantes (EISL)) to determine the prevalence of wheezing, its severity and risk factors in the first 12 months of life.17 These and other previous as well as subsequent studies have indicated that there are other factors apart from viral infections that might interact and condition the presence of recurrent wheezing (RW) in the first months of life, such as infant gender, attending nursery school, diet, characteristics of the home, pets, maternal diet during pregnancy, smoking, the presence of siblings, pneumonia, etc.1,18–21 The objective of the present study was to identify risk factors that may be acted upon in order to modify the evolution of recurrent wheezing in the first months of life. In this respect, a predictive model was developed, based on certain risk or protective factors, capable of predicting the probability of developing recurrent wheezing in the first year of life – with the evaluation of variations in probability according to changes in one or more factors.

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      2016, Allergologia et Immunopathologia
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      Prevalence of wheezing ever in infants in our study was 31.2%, a similar prevalence compared to other EISL studies conducted in Spain, in the city of Salamanca, which found 32.3%14 and in Netherlands, 28.5%,7 but less prevalence than in Latin America countries, where mean prevalence was 47.3%.15 Prevalence of recurrent wheezing was 12.3%, similar to the other Spanish EISL study,14 but lower than other European and Latin American studies.7,9 Male gender was a risk factor for wheezing ever and recurrent wheezing in our study.

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    International study of wheezing in infants, Primary Care centres of the province of Salamanca, Spain.

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