EISL study (Estudio Internacional de Sibilancias en Lactantes): A global perspective of wheezing during the first year of life

I would like to take the opportunity of including yet another paper from the EISL study in this issue of Allergologia et Immunopathologia (the first one in 2016) to dedicate this editorial to a multinational study which has been able to offer some new perspectives on a very frequent condition during the first year of life: recurrent wheezing.

The study started as a joint effort of several Latin-American and Spanish centres, with the latter addition of more Latin-American centres and another one in The Netherlands. Although as an anecdote it took some discussion with a reviewer on a particular paper, this was – definitely – an international study, which was carried out in three languages (Spanish, Portuguese and Dutch). The first phase, and the more numerous one, included up to 20 centres in 10 countries, with more than 30000 parents of infants surveyed. After validation in the study languages and in different settings,^1–4 it was launched in 2005 and was extended into 2009, depending upon the centres. Two major papers were published in 2010 including the main findings on the prevalence, treatment modalities and resource consumption together with the main risk factors.^5,6 As there were centres from very different socio-economic statuses it was possible to compare prevalence and risk factors between them. In fact the prevalence of recurrent wheezing (three or more episodes) in the first year of life was significantly higher in Latin-America as compared to Europe,⁶ and although there were some common risk and protective factors, their impact was not the same in both parts of the world. In particular, mother education was a risk factor in Latin-America while it was not in Europe.⁵ After those two summarising papers, other ones – from specific centres which were not included due to a delayed start from the core group – have been published, casting new insights into this common condition in other geographical areas.^7–14 Furthermore, new centres with a more potent questionnaire (EISL phase Three) have recently offered even a clearer picture of the problem, mainly in Latin America.^{7,10,11,15,16}

Apart from the prevalence, treatment modes, resource consumption and risk factors, other specific issues have been addressed in the EISL publications, including the effect of latitude in the strength of the association of several risk factors on recurrent wheezing,¹⁷ the relationship between wheezing and pneumonia,¹⁸ or the influence of BMI¹⁹ or low birth weight²⁰ on wheezing. Indeed other papers were focused on other allergic diseases which were secondary objectives of the EISL study, such as atopic dermatitis²¹ and rhinitis;²² the latter one extended to pres-school years.

In summary, the EISL study constitutes an example of international collaboration, and – although with the limitations of any cross-sectional study – has the power of a very large sample size and variability. Allergologia et Immnopathologia welcomes any additional paper from the EISL which focuses on new aspects of wheezing in infancy.

In the meantime, my best wishes for 2016 to all readers!