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Siblings and risk of allergic rhinitis: a systematic review and meta-analysis
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  • Daniil Lisik,
  • Saliha Selin Özuygur Ermis,
  • Athina Ioannidou,
  • Gregorio Milani,
  • Sungkutu Nyassi,
  • Giulia Spolidoro,
  • Hannu Kankaanranta,
  • Emma Goksör,
  • Göran Wennergren,
  • Bright Nwaru
Daniil Lisik
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition

Corresponding Author:daniil.lisik@gmail.com

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Saliha Selin Özuygur Ermis
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Athina Ioannidou
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Gregorio Milani
Universita degli Studi di Milano Dipartimento di Scienze Cliniche e di Comunita
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Sungkutu Nyassi
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Giulia Spolidoro
Universita degli Studi di Milano Dipartimento di Scienze Cliniche e di Comunita
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Hannu Kankaanranta
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Emma Goksör
Goteborgs universitet Sahlgrenska Akademin
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Göran Wennergren
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Bright Nwaru
Goteborgs universitet Avdelningen for invartesmedicin och klinisk nutrition
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Abstract

Following the “hygiene hypothesis”, a plethora of studies have investigated the role of sibship composition in atopic diseases, but findings are largely conflicting. We undertook the first systematic review to synthesize the global literature linking birth order and sibship size to the risk of allergic rhinitis. Fifteen databases were searched from inception until 20 th October 2021. Screening and data extraction were performed in pairs. Comparable numerical data were analyzed using meta-analysis with robust variance estimation (RVE). We included 76 reports based on 66 studies that met our inclusion criteria, encompassing >2 million subjects. Being second- or later-born child was associated with protection against both current (pooled risk ratio [RR] 0.79, 95%CI 0.73-0.86) and ever (RR 0.77, 95%CI 0.68-0.88) allergic rhinitis. Having siblings, regardless of birth order, was associated with a decreased risk of current allergic rhinitis (RR 0.89, 95% CI 0.83-0.95) and allergic rhinoconjunctivitis (RR 0.92, 95%CI 0.86-0.98). These effects were unchanged across age, time period, and geographical regions. Our findings indicate that primarily, a higher birth order, and to a lesser extent the number of siblings, is associated with a lower risk of developing allergic rhinitis.