Title：Childhood risk factors influencing adult asthma：a systematic review and meta-analysis

Background：Despite the challenge of associating childhood risk factors with adult asthma, a systematic synthesis of evidence on the risk factors is lacking. We performed a systematic review and meta-analysis of the association between childhood risk factors and adult asthma. Methods：We systematically searched the PubMed, EMBASE, Cochrane Library and Web of Science electronic databases from the inception to our last search date (10 November 2022). The search strategy included key words for risk childhood risk factors and adult asthma. The Newcastle-Ottawa scale (NOS) was used to assess the quality of the included studies. Results: Of 16 eligible articles, 16 domains of childhood risk factors were assessed. Bronchiolitis/wheezing (pooled adjusted OR=5.02; 95% CI: 2.88-8.75; I =58%; number of outcomes [N] =8), eczema (pooled adjusted OR=2.06; 95% CI: 1.44-2.95; I =82%; N=7), hay fever (pooled adjusted OR=3.31; 95% CI: 2.26-4.85; I =0%; N=2), AHR (pooled adjusted OR=2.73; 95% CI: 1.52-4.88; I =0%; N=2) and pool lung function (pooled adjusted OR=2.88; 95% CI: 1.41-5.87; I =0%; N=2) during childhood increased the risk of adult asthma and no association were detected for positive reaction of SPT (pooled adjusted OR=1.42; 95% CI: 0.64-3.17; I =70%; N=2) and adult asthma risk. There was too little evidence to draw conclusion for childhood asthma, rhinitis, sleep duration patterns, abuse, early menarche, overweight, household income, ever-smoking status during childhood, intense obstructive disease and furry pets at home in infancy. Conclusion: Childhood bronchiolitis/wheezing, eczema, hay fever, airway hyperresponsiveness (AHR) and poor lung function were associated with an increased risk of adult asthma. The identified risk factors need more interventions timely to achieve the goal of preventing adult asthma.