Sibship size, birth order and risk of asthma and allergy: protocol for a systematic review and meta-analysis

Lisik, Daniil; Ioannidou, Athina; Milani, Gregorio P.; Nyassi, Sungkutu; Ermis, Saliha Selin Özuygur; Spolidoro, Giulia Carla Immacolata; Goksör, Emma; Wennergren, Göran; Nwaru, Bright I.

doi:10.1136/bmjopen-2020-045795

Cited by 5 publications

(5 citation statements)

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“…Similarly, cases of allergic rhinitis may have been less accurately defined and/or identified in the studies that did not show a decreased risk, as indicated in the meta‐analysis on birth order and current allergic rhinitis, for which the 95% CI widened in a linear fashion in studies rated from “strong” to “weak,” with the pooled estimate from the “weak” studies indicating a nonsignificant association. Interestingly, sibship composition does not appear to have the same effect on the development of asthma, 66,67 suggesting differing underlying pathophysiological mechanisms 68 …”

Section: Discussionmentioning

confidence: 99%

“…We undertook this work following a protocol, which was registered on the International prospective register of systematic reviews (PROSPERO; CRD42020207905) and published 24 prior to undertaking the systematic review. The protocol was composed according to the Preferred Reporting Items for Systematic Review and Meta‐Analysis Protocols (PRISMA‐P) guidelines 25 .…”

Section: Methodsmentioning

confidence: 99%

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Siblings and risk of allergic rhinitis: A systematic review and meta‐analysis

Lisik

Ermis

Ioannidou

et al. 2023

Pediatric Allergy Immunology

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Following the “hygiene hypothesis” and the increase in the prevalence of atopic diseases such as allergic rhinitis, a plethora of studies have investigated the role of sibship composition as a protective factor, but findings are conflicting. The aim of this study was to synthesize the global literature linking birth order and sibship size (number of siblings) to the risk of allergic rhinitis. Fifteen databases were systematically searched, with no restrictions on publication date or language. Observational studies with defined sibship composition (birth order or sibship size) as exposure and allergic rhinitis or allergic rhinoconjunctivitis (self‐reported or clinically diagnosed) as outcome were eligible. Study selection, data extraction, and quality assessment were performed independently in pairs. Relevant data were summarized in tables. Comparable numerical data were analyzed using meta‐analysis with robust variance estimation (RVE). Seventy‐six reports with >2 million subjects were identified. 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 thus 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.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Siblings and risk of allergic rhinitis: A systematic review and meta‐analysis

Lisik

Ermis

Ioannidou

et al. 2023

Pediatric Allergy Immunology

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“…This study was conducted according to an a priori published protocol [ 31 ], which was reported following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) [ 32 ] and prospectively registered on the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020207905). We reported our work in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 33 ] checklist (supplementary table S1) and the Meta-analysis of Observational Studies in Epidemiology (MOOSE) [ 34 ] reporting guidelines (supplementary table S2).…”

Section: Methodsmentioning

confidence: 99%

Is sibship composition a risk factor for childhood asthma? Systematic review and meta-analysis

et al. 2023

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Background Following the “hygiene hypothesis”, the role of sibship composition in asthma and wheezing has been extensively studied, but the findings are inconsistent. For the first time, this systematic review and meta-analysis synthesized evidences from studies investigating the association of sibship size and birth order with risk of asthma and wheezing. Methods Fifteen databases were searched to identify eligible studies. Study selection and data extraction were performed independently by pairs of reviewers. Meta-analysis with robust variance estimation (RVE) was used to produce pooled risk ratio (RR) effect estimates from comparable numerical data. Results From 17,466 identified records, 158 reports of 134 studies (> 3 million subjects) were included. Any wheezing in the last ≤ 1.5 years occurred more frequently in infants with ≥ 1 sibling [pooled RR 1.10, 95% confidence interval (CI) 1.02–1.19] and ≥ 1 older sibling (pooled RR 1.16, 95% CI 1.04–1.29). The pooled effect sizes for asthma were overall statistically nonsignificant, although having ≥ 1 older sibling was marginally protective for subjects aged ≥ 6 years (pooled RR 0.93, 95% CI 0.88–0.99). The effect estimates weakened in studies published after 2000 compared with earlier studies. Conclusions Being second-born or later and having at least one sibling is associated with a slightly increased risk of temporary wheezing in infancy. In contrast, being second-born or later is associated with marginal protection against asthma. These associations appear to have weakened since the turn of the millennium, possibly due to lifestyle changes and socioeconomic development.

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“…This work was performed following a prospectively registered (International prospective register of systematic reviews [PROSPERO]; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=207905) and published 26 protocol, based on the Preferred Reporting Items for Systematic Review and Meta‐Analysis Protocols (PRISMA‐P) guidelines 27 . Reporting of the present work was based on the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) 28 checklist (Supporting Information S1: Table E1) and the Meta‐analysis of Observational Studies in Epidemiology (MOOSE) 29 reporting guidelines (Supporting Information S1: Table E2).…”

Section: Methodsmentioning

confidence: 99%

Birth order, sibship size, and risk of atopic dermatitis, food allergy, and atopy: A systematic review and meta‐analysis

Lisik

Ermis

Ioannidou

et al. 2023

Clinical & Translational All

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Background Atopic dermatitis and food allergy are two frequently concomitant manifestations of the presence of atopy. A substantial number of studies have been published on the association of birth order and sibship size (number of siblings) with atopic dermatitis, food allergy, and atopy. The present work is the first systematic synthesis of the existing literature on this topic. Methods Fifteen databases were searched. Screening, data extraction, and quality assessment were performed by independent pairs. Comparable numerical data were statistically synthesized using random‐effects robust variance estimation. Results In total, 114 studies were included out of 8819 papers obtained from database searches. Birth order ≥2 versus 1 was associated with lower risk of ever atopic dermatitis (pooled risk ratio [RR] 0.91, 95% CI 0.84–0.98), current food allergy (RR 0.77, 95% CI 0.66–0.90), and positive skin prick test (SPT) to common aeroallergens (RR 0.86, 95% CI 0.77–0.97). Sibship size ≥2 versus 1 was associated with decreased risk of current atopic dermatitis (RR 0.90, 95% CI 0.83–0.98), ever atopic dermatitis (RR 0.92, 95% CI 0.86–0.97), and positive SPT to common aeroallergens (RR 0.88, 95% CI 0.83–0.92). No putative associations were seen regarding atopy assessed through allergen‐specific immunoglobulin E with common allergens. Conclusion The presence of siblings and being second‐born or later may decrease the lifetime risk of atopic dermatitis and food allergy, albeit marginally. Similar association was seen with SPT sensitization. However, significant protection was not found for IgE sensitization.

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Sibship size, birth order and risk of asthma and allergy: protocol for a systematic review and meta-analysis

Cited by 5 publications

References 37 publications

Siblings and risk of allergic rhinitis: A systematic review and meta‐analysis

Siblings and risk of allergic rhinitis: A systematic review and meta‐analysis

Is sibship composition a risk factor for childhood asthma? Systematic review and meta-analysis

Birth order, sibship size, and risk of atopic dermatitis, food allergy, and atopy: A systematic review and meta‐analysis

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