Risk factors for influenza B virus-associated pneumonia in adults.

BACKGROUND: There is limited knowledge regarding the risk factors for influenza B virus-associated pneumonia in adults. This study aimed to determine the risk factors for influenza B virus-associated pneumonia in adults. METHODS: We used viral surveillance data during the pandemic season between November 2017 and April 2018 from the University of Hong Kong-Shenzhen Hospital medical record database. The files of patients ages 18 years or older were reviewed for demographics, clinical characteristics, laboratory findings, and outcome. Multivariate logistic regression analysis was performed to identify risk factors associated with influenza B virus-associated pneumonia. RESULTS: A total of 78 patients with influenza B, ages 20 to 87 years, were identified. Comparing cases with pneumonia vs cases without pneumonia, there were significant differences in the following: age in years (67.41 ± 16.63 vs 58.16 ± 17.65; P = .028), age group (74.1% vs 51.0%; P = .049), chronic respiratory diseases (70.4% vs 21.6%; P = .000), shortness of breath (40.7% vs13.7%; P = .007), abnormal breath sounds on auscultation (51.9% vs 21.6%; P = .006), and serum alanine transaminase level (30.07 ± 10.73 vs 38.64 ± 21.68; P = .022). Logistic regression models indicated that chronic respiratory diseases (odds ratio, 8.452; 95% confidence interval, 2.768-25.808; P = .000) and shortness of breath (odds ratio, 1.261; 95% confidence interval, 1.015-1.566; P = .036) were independent risk factors. CONCLUSIONS: This study suggests that chronic respiratory diseases and shortness of breath are independent risk factors for influenza B virus-associated pneumonia in adult patients.