A comparison of demographic, epidemiological and clinical characteristics of hospital influenza-related viral pneumonia patients

Background Through the comparison of the demographic, epidemiological, and clinical characteristics of hospital human influenza (influenza A (H1N1) pdm09, H3N2, and B)-related and hospitalized avian-origin influenza A (H7N9)-related viral pneumonia patients, find the different between them. Methods A retrospective study was conducted in hospitalized influenza-related viral pneumonia patients. Results Human influenza A-related patients in the 35-49-year-old group were more than those with B pneumonia patients (p = 0.027), and relatively less in the >= 65-year-old group than B pneumonia patients (p = 0.079). The proportion of comorbid condition to human influenza A pneumonia was 58%, lower than B pneumonia and H7N9 pneumonia patients (78% vs. 77.8%; p = 0.013). The proportion of invasive mechanical ventilation (IMV), lymphocytopenia, elevated lactate dehydrogenase to hospitalized human influenza A-related viral pneumonia patients was higher than B pneumonia patients (p < 0.05), but lower than H7N9 pneumonia patients (p < 0.05). In the multivariate analysis, pulmonary consolidation (odds ratio (OR): 13.67; 95% confidence interval (CI) 1.54-121.12; p = 0.019) and positive bacterial culture (sputum) (OR: 7.71; 95% CI 2.48-24.03; p < 0.001) were independently associated with IMV, while shock (OR: 13.16; 95% CI 2.06-84.07; p = 0.006), white blood cell count > 10,000/mm(3) (OR: 7.22; 95% CI 1.47-35.58; p = 0.015) and positive bacterial culture(blood or sputum) (OR: 6.27; 95% CI 1.36-28.85; p = 0.018) were independently associated with death in the three types hospitalized influenza-related viral pneumonia patients. Conclusions Hospital influenza B-related viral pneumonia mainly affects the elderly and people with underlying diseases, while human influenza A pneumonia mainly affects the young adults; however, the mortality was similar. The hospitalized human influenza A-related viral pneumonia patients was severer than B pneumonia patients, but milder than H7N9 pneumonia patients. Pulmonary consolidation and positive bacterial culture (sputum) were independently associated with IMV, while shock, white blood cell count > 10,000/mm(3), and positive bacterial culture (blood or sputum) were independently associated with death to three types hospitalized influenza-related viral pneumonia patients.