The difference in mortality between adult patients with laboratory documented influenza A and B, a single centre retrospective observational study

Background Seasonal influenza is an annual occurrence that leads to large community outbreaks and increased hospitalization. A number of studies have suggested that influenza A (FLUAV) is associated with increased rates of hospitalization and mortality compared with influenza B (FLUBV). This study compared demographic and clinical variables in patients diagnosed with FLUAV or FLUBV during the 2017-2018 UK Influenza season. Methods Patient demographic and clinical information were obtained by accessing medical records of patients testing FLUAV or FLUBV positive using the Cepheid GXP. We used the chi(2) test to compare variables in patients with laboratory-confirmed FLUAV and FLUBV. Results One hundred and twenty-seven adult patients had confirmed Influenza, 71 (55.9%) had FLUAV, and 56 (44.1%) FLUBV. There was no significant difference between severity at presentation, admission to HDU/ITU or median length of stay. The overall mortality was 6 (4.5%) and 9 (7.1%) at 7 and 30 days, respectively. There was a statistically significant difference in 7-day mortality between patients with FLUAV and FLUBV, 1 (1.4%) versus 5 (8.9%), respectively, p = .047) although this became nonsignificant at 30 days. Conclusions With the exception of mortality, we did not observe significant differences between patients with FLUAV and FLUBV. Seven-day mortality in patients with FLUBV was significantly higher with FLUAV, although this was was not apparent at 30 days.