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Vol. 113. Núm. 3.
Páginas T322-T325 (marzo 2022)
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Vol. 113. Núm. 3.
Páginas T322-T325 (marzo 2022)
Case and Research Letter
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[Translated article] Association Between Siblings and Atopic Dermatitis in a Tertiary Care Hospital
Asociación entre presencia de hermanos y dermatitis atópica en un hospital de tercer nivel de atención
W. Maldonado-Gómeza,b,
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Corresponding author.
, G. Guevara-Vásqueza
a Hospital Regional Lambayeque Chiclayo, Peru
b Facultad de Medicina Humana, Universidad Nacional Pedro Ruiz Gallo, Lambayeque, Peru
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W. Maldonado-Gómez, G. Guevara-Vásquez
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To the Editor:

Atopic dermatitis (AD) is a relapsing and remitting inflammatory skin disease characterized by flares. It appears in childhood and is caused by skin barrier defects predisposing to an increased susceptibility to allergens and irritants.1 Contradictory findings have been published on the association between having siblings and AD, with some studies reporting a protective effect and others finding no significant association.2–7 We designed a study to evaluate this association in our setting.

We performed a secondary analysis of a case-control study that analyzed 520 children (260 cases and 260 controls) under 7 years of age between May 2016 and April 2018. The children's parents or legal guardians were interviewed in a pediatric dermatology clinic at a public tertiary care hospital in the city of Chiclayo in north Peru.8 We accessed the data collected to evaluate sibship and diagnose AD using the UK Diagnostic Criteria.9

We analyzed crude and adjusted associations using the χ2 test and forward stepwise logistic regression, respectively. Qualitative variables are expressed as absolute and relative frequencies, while quantitative variables are expressed as median and interquartile range (IQR). Odds ratios (ORs) with 95% CIs and 5% P values were calculated. The analyses were performed in STATA version 14. The study was approved by the Research Ethics Committee of Hospital Regional Lambayeque.

The median age of the children was 28 months (IQR, 13–54 months); 50.4% were girls, 66.1% had at least 1 sibling, and 53.3% had a family history of allergy. The parents mostly had a high level of education (63.1% of cases) and lived in an urban environment (89.2%). In the bivariate analysis, 155 cases (59.6%) and 189 controls (72.7%) had a sibling (P=.002) (Table 1). In the logistic regression analysis, having a sibling was associated with a 44% reduced odds of having AD compared with having no siblings (OR, 0.56; 95% CI, 0.37–0.85) (Table 2).

Table 1.

Characteristics of Children With and Without Atopic Dermatitis Seen at a Tertiary Care Hospital Between 2016 and 2018.

Variable  No.  ControlsCasesP Value 
      No.  No.   
Age,moa  28 (13–54)  31.5 (13–55.5)  27 (13.5–52.5)  0.395       
Presence of siblings
No  176  33.9  71  27.3  105  40.4  .002 
Yes  344  66.1  189  72.7  155  59.6   
Exclusive breastfeeding
No  295  56.7  128  49.2  167  64.2  .001 
Yes  225  43.3  132  50.8  93  35.8   
Male  258  49.6  138  53.1  120  46.1  .114 
Female  262  50.4  122  46.9  140  53.9   
Level of education (parents)
Basic  192  36.9  131  50.4  61  23.5  <.001 
Higher  328  63.1  129  49.6  199  76.5   
Initiation of complementary feeding
Early  70  13.5  39  15.0  31  11.9  .304 
Adequate  450  86.5  221  85.0  229.00  88.1   
Smoking in presence of child
No  446  85.8  234  90.0  212  81.5  .006 
Yes  74  14.2  26  10.0  48  18.5   
Place of residence
Rural  56  10.8  39  15.0  17  6.5  .002 
Urban  464  89.2  221  85.0  243  93.5   
Family history of allergy
No  243  46.7  171  65.8  72  27.7  <.001 
Yes  277  53.3  89  34.2  188  72.3   
History of allergy (father)
No  382  73.5  225  86.5  157  60.4  <.001 
Yes  138  26.5  35  13.5  103  39.60   
History of allergy (mother)
No  379  72.9  223  85.8  156  60.0  <.001 
Yes  141  27.1  37  14.2  104  40.0   

Median (interquartile range).

Table 2.

Association Between Atopic Dermatitis and Sibship Among Children Seen at a Tertiary Care Hospital Between 2016 and 2018.

Variable  CrudeAdjusted
  OR  95% CI  P Value  OR  95% CI  P Value 
Age,moa  1.00  0.99–1.00  .255  0.99  0.99–1.00  .143 
Older siblings
No    .002    .007 
Yes  0.55  0.38–0.80    0.56  0.37–0.85   
Exclusive breastfeeding
No    .001       
Yes  0.54  0.38–0.77         
Male    .115    .159 
Female  1.32  0.93–1.86    1.32  0.90–1.96   
Level of education (parents)
Basic    <.001    <.001 
Higher  3.31  2.27–4.83    2.37  1.54–3.63   
Initiation of complementary feeding
Early    .305       
Adequate  1.30  0.79–2.16         
Smoking in presence of child
No    .006    .046 
Yes  2.04  1.22–3.40    1.79  1.01–3.18   
Place of residence
Rural    0.002    0.953 
Urban  2.52  1.39–4.59    1.02  0.52–2.01   
Family history of allergy
No    <.001    <.001 
Yes  5.01  3.45–7.29    4.65  3.11–6.95   
History of allergy (father)
No    <.001       
Yes  4.22  2.73–6.51         
History of allergy (mother)
No    <.001       
Yes  4.02  2.62–6.16         

Abbreviation: OR, odds ratio.


Adjusted for history of allergy in direct relative, maximum level of education of parents, smoking in presence of child, age, sex, and place of residence.

Conflicting findings have been described for the association between sibship and AD. One possible reason is the use of different definitions of AD. Gibbs,4 for example, used the same criteria as us to diagnose AD and reported similar findings. Criteria-based assessment of AD has been found to offer greater diagnostic certainty compared with questionnaire-based measures.10

Contradictory results might also be due to population differences, as other hospital-based studies have also found sibship to exert a protective effect against AD.4,5 A similar effect has been found in population studies. In a cross-sectional study of 24,999 schoolchildren aged between 6 and 8 years in Taipei, Taiwan, Ho et al.,6 found that having older siblings reduced the odds of AD (OR, 0.83; 95% CI: 0.76–0.92; P<.001), while Ohfuji et al.,2 in a similar study of children aged 6 to 15 years in Japan, found a significant inverse relationship between number of siblings and presence of AD. Sacchetti et al.,7 by contrast, did not detect a significant association between number of siblings and presence of AD in schoolchildren aged 5 to 8 years in Italy, but they evaluated AD under the umbrella of allergic disease. Finally, Benn et al.,3 in a cohort study of newborns, found that children with siblings had a higher risk of AD. The follow-up time, however, was just 18 months, which represents a limitation as AD can develop up to the age of 5 years.

Our findings should be interpreted with caution as we did not analyze variables related to sibship, such as number of siblings or birth order. Another limitation is that we performed a secondary analysis of data from a study designed to evaluate the protective effect of exclusive breastfeeding on the development of AD. More studies analyzing the association between sibship and AD, with consideration of related variables, are needed. Despite its limitations, the current study sheds some light on the association between sibship and AD in Peru and Latin America.


The authors declare that they did not receive any funding for this study.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

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