Community-acquired pneumonia in hospitalised patients : changes in aetiology, clinical presentation, and severity outcomes in a 10-year period

Community-acquired pneumonia (CAP) is a frequent cause of hospitalisation. Several factors, such as pandemics, vaccines and globalisation may lead to changes in epidemiology, clinical presentation, and outcomes of CAP, which oblige to a constant actualisation. We performed this study to analyse how these factors have evolved over a 10-year period. Patients diagnosed with CAP for two 1-year periods that were 10 years apart (2007-2008 and 2017-2018) were included. We compared microbiological information, clinical data and evolutive outcomes in the two periods. A mortality analysis was performed. 1043 patients were included: 452 during the first period (2007- 2008), and 591 during the second period (2017-2018). Bacterial aetiology did not change during the 10-year period, besides a slight increase in Staphylococcus aureus (0.9% vs 2.9%, p = 0.026). There was a decline in the proportion of bacteraemia in the second period (14.8% vs 9.6%, p = 0.012). The incidence of complicated pleural effusion and septic shock declined too (6.4% vs 3.6%, p = 0.04 and 15.5% vs 6.3%, p < 0.001). Respiratory failure and Intensive care unit (ICU) admission were similar in both periods. Variables independently associated with mortality were age and septic shock. Influenza vaccine was a protective factor against mortality in the second period. We have not found relevant differences in the bacterial aetiology of CAP over this 10-year period. There has been a decline in septic complications of CAP such as septic shock, bacteraemia, and complicated pleural effusion. Influenza vaccination is an important tool to reduce mortality