The burden due to influenza-related hospitalization is heavy in children under 5 years old, a high-risk group of severe influenza, but there is little research on the risk factors for such hospitalizations.

To explore the risk factors for influenza A variant virus-related hospitalization in children under 5 years old.

A retrospective design was used. Children under five years old (n=1 450) with influenza A virus infection were selected from Emergency Department, Beijing Ditan Hospital Capital Medical University during December 2018 to February 2019. Clinical data were collected, including age, sex, baseline chronic disease, time from onset to first contact, time from onset to initiation of antiviral therapy, main clinical features and prevalence of hospitalization. Multivariate Logistic regression analysis was used to identify the risk factors of hospitalization.

The median age for the children was 2.5 (1.1, 3.9) years, and males outnumbered females (56.5% vs 43.5%) . Thirty-eight (2.6%) had baseline chronic diseases, and 155 (10.7%) were hospitalized. Stepwise univariate and multivariate Logistic regression analyses showed that: younger than 6 months〔OR=5.808, 95%CI (2.650, 12.730) , P<0.001〕, male〔OR=1.673, 95%CI (1.098, 2.549) , P<0.05〕, accompanied with baseline chronic diseases〔OR=17.999, 95%CI (7.882, 41.103) , P<0.001〕, time from onset to first visit>48 h〔OR=4.663, 95%CI (1.712, 12.704) , P<0.001〕, the time from onset to initiation of antiviral treatment >48 h〔OR=19.835, 95%CI (9.043, 43.502) , P<0.001〕, prevalence of cough or expectoration symptoms〔OR=7.174, 95%CI (4.222, 12.191) , P<0.001〕and prevalence of disturbance of consciousness / convulsions〔OR=10.044, 95%CI (6.142, 16.425) , P<0.001〕were associated with increased risk of hospitalization.

In children under 5 years old, male, younger than 6 months, and baseline chronic diseases may be risk factors for influenza A variant virus-related hospitalization, cough/expectoration, and disturbance of consciousness/ convulsions may be associated with even higher risk. Early use of antiviral therapy could reduce the risk of hospitalization.

5岁以下儿童作为重症流感的高危人群，住院负担较重，但目前对其住院危险因素方面的研究却很少。

探讨5岁以下甲型流感患儿住院的危险因素。

回顾性分析2018年12月至2019年2月北京地坛医院感染急诊收治的5岁以下甲型流感患儿1 450例，收集其年龄、性别、合并慢性基础疾病、发病至首次就诊时间、发病至抗病毒治疗时间、主要临床表现及是否住院治疗等临床特征。采用多因素Logistic回归分析探讨甲型流感患儿住院的危险因素。

1 450例甲型流感患儿的中位年龄为2.5（1.1，3.9）岁，男童多于女童（56.5% vs 43.5%），38例（2.6%）患儿合并慢性基础疾病，155例（10.7%）患儿需住院治疗。逐步对各分析变量进行单因素及多因素Logistic回归分析显示：年龄<6月龄〔OR=5.808，95%CI（2.650，12.730），P<0.001〕、男童〔OR=1.673，95%CI（1.098，2.549），P<0.05〕、合并慢性基础疾病〔OR=17.999，95%CI（7.882，41.103），P<0.001〕、发病至首次就诊时间>48 h〔OR=4.663，95%CI（1.712，12.704），P<0.001〕、发病至抗病毒治疗时间>48 h〔OR=19.835，95%CI（9.043，43.502），P<0.001〕、存在咳嗽/咳痰〔OR=7.174，95%CI（4.222，12.191），P<0.001〕、存在意识障碍/抽搐〔OR=10.044，95%CI（6.142，16.425），P<0.001〕均为甲型流感患儿住院的独立危险因素。

男性、年龄<6月龄及合并慢性基础疾病是5岁以下甲型流感患儿住院的高危因素。存在咳嗽/咳痰，意识障碍/抽搐的患儿住院风险更高，早期使用抗病毒药物治疗可降低住院风险。