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DOI: 10.1055/s-0040-1717140
Clinical Profile of Episodic Wheezing and Multiple Trigger Wheezing in Preschool Children: A Cross-Sectional Study
Abstract
The objectives of our study were to identify the relative frequency of episodic viral wheeze (EVW) and multiple trigger wheeze (MTW) in preschool children of 1 to 5 years of age with recurrent wheezing and to compare the relevant clinical and sociodemographic parameters in the above phenotypes. This cross-sectional study included 165 children aged 1 to 5 years with recurrent wheeze. Participants were categorized into EVW and MTW based on history according to European Respiratory Society Task Force recommendations 2008. Symptom control was assessed by Global Initiative for Asthma guidelines 2015. Of the total participants, EVW was seen in 55% and MTW in 45%. Children with MTW were significantly older than those with EVW, more atopic, and had higher eosinophil counts. The dominant phenotype seen in our study was EVW. The absence of ocular/nasal allergy and exclusive breastfeeding predicted well-controlled symptoms in EVW and in all preschool wheezers, respectively.
#
Introduction
Preschool wheezers are twice more likely to visit hospitals and thrice more likely to be admitted compared with older children.[1] An essential requirement for better management of these children is to classify them as either episodic viral wheezers (EVWs) or multiple trigger wheezers (MTWs) based on European Respiratory Society (ERS) Task Force recommendations 2008.[2] Although these phenotypes were found by some authors to change over time,[3] [4] [5] a recent study by Spycher et al indicates that they remain stable.[6] A significant number of them, particularly the MTW, are likely to have symptoms consistent with asthma and reduced lung capacity later in life.[7] [8] The identification of these phenotypes help in predicting long-term outcomes and also to identify high-risk children who might benefit from secondary preventive interventions. There are only few studies comparing the clinical and sociodemographic profiles of these two phenotypes and none among Indian children. Hence, this study was performed to identify the relative frequency of EVW and MTW in preschool children 1 to 5 years of age with wheezing and to compare the relevant clinical and sociodemographic parameters in the above phenotypes.
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Methods
This cross-sectional study was conducted in the Department of Pediatrics, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, a tertiary care teaching institute from December 2015 to December 2017 after obtaining approval from our institute ethics committee. Preschool children (1–5 years of age), who were on follow-up in the childhood asthma clinic for at least 3 consecutive months and diagnosed by a doctor to have recurrent wheeze participated in this study. Children with pneumonia, history suggestive of gastroesophageal reflux disease, congenital heart disease, stridor, history suggestive of foreign body, bronchopulmonary dysplasia, bronchiectasis, immunodeficiency, and anatomic abnormalities leading to recurrent aspiration were not enrolled.
We recruited 165 children, who fulfilled the inclusion criteria during the study period ([Fig. 1]). The participants were classified into EVW and MTW as per ERS Task Force guidelines 2008. Children who had history of wheezing during discrete time periods, following viral infections, with absence of wheeze between episodes were categorized as EVW. Children who had history of discrete exacerbations of wheeze and also had symptoms in between episodes of viral infections were categorized as MTW.[2]
For all participants, data on rural or urban location and parental literacy were recorded. Socioeconomic status (SES) was classified based on modified Kuppuswamy scale 2014.[9] History regarding the age of onset, frequency of symptoms, bronchiolitis in the past, frequency of wheeze exacerbations, triggers, seasonality, personal and family history of atopy, exposure to environmental smoke, prematurity, low birth weight, neonatal respiratory distress, breastfeeding status, immunization status, investigation, and treatment details were noted. Weight and height were measured and classified according to the World Health Organization guidelines.[10] Symptom control was assessed based on Global Initiative for Asthma (GINA) 2015 guidelines.[11] In our study, we classified the well-controlled symptom group in GINA 2015 as “well-controlled symptom group” and the partly and uncontrolled groups together as “uncontrolled symptom group.” The Institute Ethics Committee—Human Studies of our institute approved the study (JIP/IEC/2015/22/776).
Statistical Analysis
Continuous variables were expressed as median with interquartile range (IQR). Categorical variables were expressed as proportions. Mann–Whitney's U test was done for quantitative variables and chi-square test was used for categorical variables. Multiple logistic regression analysis was done for factors associated with symptom control for both EVW and MTW and also for all the participants combined. For statistical analysis, Statistical Package for the Social Sciences (SPSS) version 19 by International Business Machines (IBM) Corporation was used.
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Results
The median age of the study population was 42 months with an IQR of 27.5 to 51.5. Boys were 110 (66.7%) in number; children belonging to rural areas were 98 (59.4%). Two children (1.2%) belonged to lower, 38 (23%) belonged to upper lower, 72 (43.8%) belonged to lower middle, 35 (21%) belonged to upper middle, and 18 (11%) belonged to upper socioeconomic classes. Majority were born at term (91.5%) with normal birth weight (78.1%), were exclusively breastfed (92.1%) in the first 6 months, and were completely immunized (97%) for age as per national schedule. EVW was seen in 91 (55%) and MTW in 74 (45%) children. Median age was significantly higher in the MTW group. The two groups did not significantly differ in breastfeeding status, immunization status, prematurity, low birth weight, neonatal respiratory distress, bronchiolitis in infancy, age of onset, and duration of treatment ([Table 1]). The number of children on montelukast was higher in EVW group; those on inhaled corticosteroids (ICSs) were higher in MTW group and this finding was statistically significant. A significantly higher proportion of parental atopy and high absolute eosinophil count (AEC) was seen in children with MTW. Seasonality of exacerbation was present in 35 (47.3%) children with MTW. Viral infections in 67 (90.5%) children, dust allergy in 46 (62.1%) children, environmental smoke exposure in 23 (31.1%) children, and food allergens in 21 (28.3%) children were the common triggers identified in MTW group. Out of 91 children with EVW, 79 (86.8%) had well-controlled symptoms, whereas 12 (13.2%) had uncontrolled symptoms. Among the 74 MTW, 58 (78.4%) had well-controlled symptoms and 16 (21.6%) had uncontrolled symptoms. There was no significant difference in the symptom control among EVW and MTW.
|
Variable |
Episodic wheezer n = 91 (%) |
Multitrigger wheezer n = 74 (%) |
p-Value (chi-square) |
|
|---|---|---|---|---|
|
Median age in mo (interquartile range) |
36 (24–48) |
42 (36–54) |
0.003[a] |
|
|
Male gender |
64 (70.3) |
46 (62.2) |
0.268 |
|
|
Rural residence |
52 (57.1) |
46 (62.2) |
0.514 |
|
|
Socioeconomic status |
Lower |
2 (2.2) |
0 |
0.772 |
|
Upper lower |
19 (20.9) |
19 (25.7) |
||
|
Lower middle |
39 (42.9) |
33 (44.6) |
||
|
Upper middle |
21 (23.1) |
14 (18.9) |
||
|
Upper |
10 (11) |
8 (10.8) |
||
|
Prematurity |
8 (8.8) |
6 (8.1) |
0.876 |
|
|
Low birth weight |
17 (18.7) |
20 (27) |
0.201 |
|
|
Exclusive breastfeeding for 6 mo |
85 (93.4) |
67 (90.5) |
0.568 |
|
|
Median duration of breastfeeding in mo (interquartile range) |
13 (12–18) |
18 (12–18) |
0.261[a] |
|
|
Complete immunization status |
88 (96.7) |
72 (97.3) |
0.463 |
|
|
Neonatal respiratory distress |
5 (5.5) |
9 (12.2) |
0.126 |
|
|
Bronchiolitis in infancy |
47 (51.6) |
32 (43.2) |
0.282 |
|
|
Median age of symptom onset in mo (interquartile range) |
10 (6–18) |
12 (5.75–25) |
0.547[a] |
|
|
Frequency of exacerbations |
≤2 in 6 mo |
17 (18.7) |
8 (10.8) |
0.161[b] |
|
>2 in 6 mo |
74 (81.3) |
66 (89.2) |
||
|
Controller medications |
Montelukast |
39 (42.9) |
8 (10.8) |
0.001[b] |
|
ICS |
49 (53.8) |
66 (89.2) |
||
|
None |
3 (3.3) |
0 |
||
|
Median duration of treatment in mo (interquartile range) |
3 (3–6) |
3.5 (3–8.25) |
0.119[a] |
|
|
Median absolute eosinophil count (interquartile range)[c] |
292 (132.5–485) |
850 (260–1,630) |
0.001[a] |
|
|
H/o atopic eczema |
2 (2.2) |
16 (21.6) |
0.001[b] |
|
|
H/o ocular/nasal allergy |
5 (5.5) |
34 (45.9) |
0.001[b] |
|
|
Parental atopy |
12 (13.2) |
44 (59.5) |
0.001[b] |
|
Abbreviations: H/o, history of; ICS, inhaled corticosteroid.
a p-Value calculated using Mann–Whitney's U test.
b pValue calculated using chi-square test.
c For 94 children.
On univariate analysis of factors associated with symptom control in EVW group ([Table 2]), it was found that children with either parent or both graduates had a higher percentage of uncontrolled symptoms with an odds ratio (OR) of 8.5 (95% confidence interval [CI]: 2.2–32.1). Those with history of ocular/nasal allergies had more uncontrolled symptoms (OR: 12.8, 95% CI: 1.8–87.3). Other factors such as gender, SES, anthropometric parameters, prematurity, birth weight, breastfeeding, neonatal respiratory distress, bronchiolitis, environmental smoke exposure, AEC, and type and duration of treatment were not significantly associated. Among MTW ([Table 3]), only exclusive breastfeeding in the first 6 months of life predicted well-controlled symptoms (OR: 6.1, 95% CI: 1.2–30.9).
Abbreviations: CI, confidence interval; H/o, history of; NA, not available; RD, respiratory disease; SES, socioeconomic status.
Abbreviations: CI, confidence interval; H/o, history of; RD, respiratory disease; SES, socioeconomic status.
On univariate analysis among all participants ([Table 4]), wheezers with both parents being graduates had higher chance of having uncontrolled symptoms (OR: 2.5, 95% CI: 1–5.9), and so were those who had nasal/ocular allergy (OR: 2.5, 95% CI: 1–5.9) and those not exclusively breastfed (OR: 5, 95% CI: 1.5–16.4). On multiple (binomial) logistic regression in the EVW group, absence of ocular/nasal allergies predicted well-controlled symptoms (OR: 20.4, 95% CI: 1.9–216.6). On multiple (binomial) logistic regression analysis among preschool wheezers in general, exclusive breastfeeding in the first 6 months of life predicted well-controlled symptoms (OR: 4.1, 95% CI: 1.2–14.4).
Abbreviations: CI, confidence interval; H/o, history of; RD, respiratory disease; SES, socioeconomic status.
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Discussion
From our study results, we find that EVW is the dominant phenotype. Children with MTW were older than EVW, were mostly on ICS, and had more parental atopy, personal atopy, and higher AEC. In the EVW group, symptoms were more likely to be significantly well controlled in the absence of ocular or nasal allergy. In preschool wheezers as a whole, exclusive breastfeeding in the first 6 months of life was associated with well-controlled symptoms.
It is generally known that the proportion of MTW increases and EVW decreases over time.[12] [13] In a study involving 109 children in the age group of 2 to 6 years, Schultz et al found that 35% had EVW and 65% had MTW at baseline and 31% had EVW, 47% had MTW, and 22% had no wheeze at 1-year follow-up.[4] We did not find significant difference in the age of onset, frequency of exacerbations, or duration of treatment between EVW and MTW, but there was difference in the type of treatment, AEC, and parental atopy. Mutti et al in their study on 55 children have reported no significant difference between the age of onset, atopic status, and airway eosinophilia in EVW compared with MTW.[14] Significantly higher AEC and family history of atopy were seen in MTW in our study as MTW represents an atopic phenotype.[5] [12] [13] [15] [16] [17] [18] On univariate analysis, we found that more children whose parents were graduates had uncontrolled symptoms. These children also had higher parental allergy and environmental smoke exposure. Previous studies have found that parental allergies were independent risk factors for developing persistent wheeze.[19] [20] It is also known that lower parental education and low SES are associated with poorer symptom control.[19] [21] However, in our study, we find that parents who were graduates were a risk factor for uncontrolled symptom on univariate analysis, but it was not confirmed in multiple logistic regression indicating that the discrepancy may be probably due to confounders. We also found that EVW without ocular/nasal allergy were more likely to have well-controlled symptoms. It is a well-known fact that allergic rhinitis can have a negative effect on symptom control.[22] Although atopy is more often associated with MTW, in our study, we found they may be associated with EVW also and further serves to support the observations of the ERS Task Force statement that there may be overlap between the two phenotypes.[2] Consistent with the conclusions of previous studies,[23] [24] [25] we also found that exclusive breastfeeding predicted well-controlled symptoms in all preschool wheezers in general.
The limitations of our study are that the sample was drawn from an asthma clinic and not from the community. It was a cross-sectional design and AEC was not available for 92 children. Information regarding breastfeeding and immunization was obtained based on history obtained from parents and information available in the case records (for immunization).
#
Conclusion
To conclude, EVW is the dominant wheezing phenotype found in preschool children. Children with MTW phenotype tend to be older than EVW phenotype and tend to have higher AECs. Atopy in the form of ocular and nasal allergies can also be seen in children with EVW and its absence predicts well-controlled symptoms. Exclusive breastfeeding predicts well-controlled symptoms in children with preschool wheeze in general irrespective of the phenotypes.
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Conflict of Interest
None declared.
Authors' Contributions
Both the authors were involved in the study design, data collection, analysis, literature review, and drafting of the manuscript, and reviewed the manuscript for intellectual content and seen and approved the final draft. The authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
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References
- 1 Beigelman A, Bacharier LB. Management of preschool children with recurrent wheezing: lessons from the NHLBI's asthma research networks. J Allergy Clin Immunol Pract 2016; 4 (01) 1-8 , quiz 9–10
- 2 Brand PLP, Baraldi E, Bisgaard H. et al. Definition, assessment and treatment of wheezing disorders in preschool children: an evidence-based approach. Eur Respir J 2008; 32 (04) 1096-1110
- 3 Schultz A, Brand PLP. Episodic viral wheeze and multiple trigger wheeze in preschool children: a useful distinction for clinicians?. Paediatr Respir Rev 2011; 12 (03) 160-164
- 4 Schultz A, Devadason SG, Savenije OEM, Sly PD, Le Souëf PN, Brand PLP. The transient value of classifying preschool wheeze into episodic viral wheeze and multiple trigger wheeze. Acta Paediatr 2010; 99 (01) 56-60
- 5 van Wonderen KE, Geskus RB, van Aalderen WMC. et al. Stability and predictiveness of multiple trigger and episodic viral wheeze in preschoolers. Clin Exp Allergy 2016; 46 (06) 837-847
- 6 Spycher BD, Cochrane C, Granell R. et al. Temporal stability of multitrigger and episodic viral wheeze in early childhood. Eur Respir J 2017; 50 (05) 1700014
- 7 Pin I, Siroux V, Boudier A, Vignoud-Nicollet L, Just J, Kauffmann F. Long-term evolution of virus-induced and multi-trigger wheeze in children of the EGEA study. Eur Respir J 2011; 38: 1507
- 8 Tagiyeva N, Devereux G, Fielding S, Turner S, Douglas G. Outcomes of childhood asthma and wheezy bronchitis. A 50-year cohort study. Am J Respir Crit Care Med 2016; 193 (01) 23-30
- 9 Oberoi SS. Updating income ranges for Kuppuswamy's socio-economic status scale for the year 2014. Indian J Public Health 2015; 59 (02) 156-157
- 10 WHO. WHO Child Growth Standards: Methods and development [Internet]. WHO; Available at: http://www.who.int/childgrowth/standards/technical_report/en/. Accessed January 28, 2018
- 11 GINA_Report_2015_Aug11–1.pdf [Internet]. Available at: http://ginasthma.org/wp-content/uploads/2016/01/GINA_Report_2015_Aug11-1.pdf . Accessed January 28, 2018
- 12 Just J, Saint-Pierre P, Gouvis-Echraghi R. et al. Wheeze phenotypes in young children have different courses during the preschool period. Ann Allergy Asthma Immunol 2013; 111 (04) 256-261.e1
- 13 Jurca M, Pescatore AM, Goutaki M, Spycher BD, Beardsmore CS, Kuehni CE. Age-related changes in childhood wheezing characteristics: a whole population study. Pediatr Pulmonol 2017; 52 (10) 1250-1259
- 14 Mutti E, Baraldo S, Bazzan E. et al. Defining phenotypes of wheeze at preschool age: comparison of episodic vs. multitrigger wheeze. Eur Respir J 2014; 44: 429
- 15 Ulrik CS. Peripheral eosinophil counts as a marker of disease activity in intrinsic and extrinsic asthma. Clin Exp Allergy 1995; 25 (09) 820-827
- 16 Castro-Rodríguez JA, Holberg CJ, Wright AL, Martinez FD. A clinical index to define risk of asthma in young children with recurrent wheezing. Am J Respir Crit Care Med 2000; 162 (4 Pt 1): 1403-1406
- 17 Kurukulaaratchy RJ, Fenn M, Matthews S, Arshad SH. Characterisation of atopic and non-atopic wheeze in 10 year old children. Thorax 2004; 59 (07) 563-568
- 18 de Sousa RB, Medeiros D, Sarinho E, Rizzo JÂ, Silva AR, Bianca ACD. Risk factors for recurrent wheezing in infants: a case-control study. Rev Saude Publica 2016; 50: 15
- 19 Taylor-Robinson DC, Pearce A, Whitehead M, Smyth R, Law C. Social inequalities in wheezing in children: findings from the UK Millennium Cohort Study. Eur Respir J 2016; 47 (03) 818-828
- 20 Caudri D, Savenije OEM, Smit HA. et al. Perinatal risk factors for wheezing phenotypes in the first 8 years of life. Clin Exp Allergy 2013; 43 (12) 1395-1405
- 21 Uphoff E, Cabieses B, Pinart M, Valdés M, Antó JM, Wright J. A systematic review of socioeconomic position in relation to asthma and allergic diseases. Eur Respir J 2015; 46 (02) 364-374
- 22 (*NEW) 2017 GINA Report: Global Strategy for Asthma Management and Prevention [Internet]. Global Initiative for Asthma -GINA. Available at: http://ginasthma.org/2017-gina-report-global-strategy-for-asthma-management-and-prevention/ . Accessed January 4, 2018
- 23 Guibas GV, Xepapadaki P, Moschonis G. et al. Breastfeeding and wheeze prevalence in pre-schoolers and pre-adolescents: the Genesis and Healthy Growth studies. Pediatr Allergy Immunol 2013; 24 (08) 772-781
- 24 den Dekker HT, Sonnenschein-van der Voort AMM, Jaddoe VWV, Reiss IK, de Jongste JC, Duijts L. Breastfeeding and asthma outcomes at the age of 6 years: the Generation R Study. Pediatr Allergy Immunol 2016; 27 (05) 486-492
- 25 Sonnenschein-van der Voort AMM, Jaddoe VWV, van der Valk RJP. et al. Duration and exclusiveness of breastfeeding and childhood asthma-related symptoms. Eur Respir J 2012; 39 (01) 81-89
Address for correspondence
Publikationsverlauf
Eingereicht: 26. Juli 2020
Angenommen: 20. August 2020
Artikel online veröffentlicht:
15. Oktober 2020
© 2020. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).
Georg Thieme Verlag KG
Stuttgart · New York
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References
- 1 Beigelman A, Bacharier LB. Management of preschool children with recurrent wheezing: lessons from the NHLBI's asthma research networks. J Allergy Clin Immunol Pract 2016; 4 (01) 1-8 , quiz 9–10
- 2 Brand PLP, Baraldi E, Bisgaard H. et al. Definition, assessment and treatment of wheezing disorders in preschool children: an evidence-based approach. Eur Respir J 2008; 32 (04) 1096-1110
- 3 Schultz A, Brand PLP. Episodic viral wheeze and multiple trigger wheeze in preschool children: a useful distinction for clinicians?. Paediatr Respir Rev 2011; 12 (03) 160-164
- 4 Schultz A, Devadason SG, Savenije OEM, Sly PD, Le Souëf PN, Brand PLP. The transient value of classifying preschool wheeze into episodic viral wheeze and multiple trigger wheeze. Acta Paediatr 2010; 99 (01) 56-60
- 5 van Wonderen KE, Geskus RB, van Aalderen WMC. et al. Stability and predictiveness of multiple trigger and episodic viral wheeze in preschoolers. Clin Exp Allergy 2016; 46 (06) 837-847
- 6 Spycher BD, Cochrane C, Granell R. et al. Temporal stability of multitrigger and episodic viral wheeze in early childhood. Eur Respir J 2017; 50 (05) 1700014
- 7 Pin I, Siroux V, Boudier A, Vignoud-Nicollet L, Just J, Kauffmann F. Long-term evolution of virus-induced and multi-trigger wheeze in children of the EGEA study. Eur Respir J 2011; 38: 1507
- 8 Tagiyeva N, Devereux G, Fielding S, Turner S, Douglas G. Outcomes of childhood asthma and wheezy bronchitis. A 50-year cohort study. Am J Respir Crit Care Med 2016; 193 (01) 23-30
- 9 Oberoi SS. Updating income ranges for Kuppuswamy's socio-economic status scale for the year 2014. Indian J Public Health 2015; 59 (02) 156-157
- 10 WHO. WHO Child Growth Standards: Methods and development [Internet]. WHO; Available at: http://www.who.int/childgrowth/standards/technical_report/en/. Accessed January 28, 2018
- 11 GINA_Report_2015_Aug11–1.pdf [Internet]. Available at: http://ginasthma.org/wp-content/uploads/2016/01/GINA_Report_2015_Aug11-1.pdf . Accessed January 28, 2018
- 12 Just J, Saint-Pierre P, Gouvis-Echraghi R. et al. Wheeze phenotypes in young children have different courses during the preschool period. Ann Allergy Asthma Immunol 2013; 111 (04) 256-261.e1
- 13 Jurca M, Pescatore AM, Goutaki M, Spycher BD, Beardsmore CS, Kuehni CE. Age-related changes in childhood wheezing characteristics: a whole population study. Pediatr Pulmonol 2017; 52 (10) 1250-1259
- 14 Mutti E, Baraldo S, Bazzan E. et al. Defining phenotypes of wheeze at preschool age: comparison of episodic vs. multitrigger wheeze. Eur Respir J 2014; 44: 429
- 15 Ulrik CS. Peripheral eosinophil counts as a marker of disease activity in intrinsic and extrinsic asthma. Clin Exp Allergy 1995; 25 (09) 820-827
- 16 Castro-Rodríguez JA, Holberg CJ, Wright AL, Martinez FD. A clinical index to define risk of asthma in young children with recurrent wheezing. Am J Respir Crit Care Med 2000; 162 (4 Pt 1): 1403-1406
- 17 Kurukulaaratchy RJ, Fenn M, Matthews S, Arshad SH. Characterisation of atopic and non-atopic wheeze in 10 year old children. Thorax 2004; 59 (07) 563-568
- 18 de Sousa RB, Medeiros D, Sarinho E, Rizzo JÂ, Silva AR, Bianca ACD. Risk factors for recurrent wheezing in infants: a case-control study. Rev Saude Publica 2016; 50: 15
- 19 Taylor-Robinson DC, Pearce A, Whitehead M, Smyth R, Law C. Social inequalities in wheezing in children: findings from the UK Millennium Cohort Study. Eur Respir J 2016; 47 (03) 818-828
- 20 Caudri D, Savenije OEM, Smit HA. et al. Perinatal risk factors for wheezing phenotypes in the first 8 years of life. Clin Exp Allergy 2013; 43 (12) 1395-1405
- 21 Uphoff E, Cabieses B, Pinart M, Valdés M, Antó JM, Wright J. A systematic review of socioeconomic position in relation to asthma and allergic diseases. Eur Respir J 2015; 46 (02) 364-374
- 22 (*NEW) 2017 GINA Report: Global Strategy for Asthma Management and Prevention [Internet]. Global Initiative for Asthma -GINA. Available at: http://ginasthma.org/2017-gina-report-global-strategy-for-asthma-management-and-prevention/ . Accessed January 4, 2018
- 23 Guibas GV, Xepapadaki P, Moschonis G. et al. Breastfeeding and wheeze prevalence in pre-schoolers and pre-adolescents: the Genesis and Healthy Growth studies. Pediatr Allergy Immunol 2013; 24 (08) 772-781
- 24 den Dekker HT, Sonnenschein-van der Voort AMM, Jaddoe VWV, Reiss IK, de Jongste JC, Duijts L. Breastfeeding and asthma outcomes at the age of 6 years: the Generation R Study. Pediatr Allergy Immunol 2016; 27 (05) 486-492
- 25 Sonnenschein-van der Voort AMM, Jaddoe VWV, van der Valk RJP. et al. Duration and exclusiveness of breastfeeding and childhood asthma-related symptoms. Eur Respir J 2012; 39 (01) 81-89