The epidemiological and clinical characteristics of the hospital-acquired influenza infections: A systematic review and meta-analysis

BACKGROUND: The hospital-acquired influenza (HAI) were usually contributed to severe outcomes among the inpatients. Here, we performed a meta-analysis to summarize and quantify the epidemiological and clinical characteristics of HAI. METHODS: We performed a literature search thorough PubMed, Web of Science, Cochrane Library, Embase, Scopus and China National Knowledge Infrastructure (CNKI), and Wanfang databases for observational studies. Random/fix-effects models were used to obtain pooled proportion, odds ratio (OR), and weighted mean difference (WMD). RESULTS: A total of 14 studies involving 1483 HAI and 71849 non-hospital-acquired influenza infections (NHAI) cases were included.The proportion of the HAI among the influenza cases was 11.38% (95% confidence interval [CI]: 5.19%–19.55%) and it was increased after 2012 (6.15% vs 12.72%). The HAI cases were significantly older (WMD = 9.51, 95% CI: 0.04–18.98) and the patients with chronic medical diseases were at increased risk of HAI (OR = 1.85, 95% CI: 1.57–2.19). Among them, metabolic disorders (OR = 8.10, 95% CI: 2.46–26.64) ranked the highest danger, followed by malignancy (OR = 3.18, 95% CI: 2.12–4.76), any chronic diseases (OR = 2.81, 95% CI: 1.08–9.31), immunosuppression (OR = 2.13, 95% CI: 1.25–3.64), renal diseases (OR = 1.72, 95% CI:1.40–2.10), heart diseases (OR = 1.52, 95% CI: 1.03–1.44), and diabetes (OR = 1.22, 95% CI: 1.03–1.44). The HAI cases were more likely to experience longer hospital stay (WMD = 10.23, 95% CI: 4.60–15.85) and longer intensive care unit (ICU) stay (WMD = 2.99, 95% CI: 1.50–4.48). In the outcomes within 30 days, those population was still more likely to receive hospitalization (OR = 6.55, 95% CI: 5.19–8.27), death in hospital (OR = 1.99, 95% CI: 1.65–2.40) but less likely to discharged (OR = 0.20, 95% CI: 0.16–0.24). CONCLUSION: The proportion of the HAI among the influenza cases was relatively high. Reinforcement of the surveillance systems and vaccination of the high-risk patients and their contacts are necessary for the HAI control.