Burden of pneumonia in patients with viral and bacterial coinfection in Spain during six consecutive influenza seasons, from 2009–10 to 2014–15

Abstract

PurposeLower respiratory infections remain the most lethal communicable disease worldwide. Viral and bacterial coinfections (VBC) are common complications in patients with seasonal influenza and are associated with around 25% of all influenza-related deaths. The burden of pneumonia in patients with VBC in Spain is poorly characterized. To address this question, we aimed to provide population data over a period of six consecutive influenza seasons, from 2009–10 to 2014–15. MethodsWe used the discharge report from the Minimum Basic Data Set (MBDS), published annually by the Spanish Ministry of Health, to retrospectively analyse hospital discharge data in individuals aged ≥60 years with a diagnosis of pneumonia and influenza, based on the International Classification of Diseases (ICD-9-CM codes 480–486 and 487–488, respectively), from 1 October 2009 to 30 September 2015. ResultsIn total, 1933 patients ≥60 years old were hospitalized for pneumonia and influenza, of whom 55.2% were male. The median age was 74 years (interquartile range [IRQ] 15); half of the patients were ≥75 years old. Influenza was the main diagnosis in 64.4% of the patients, and all–cause pneumonia in 15.8%, half of whom were assigned a diagnostic code for pneumococcal pneumonia. The mean annual hospitalization rate was 2.99 per 100,000 population (95% CI 2.9–3.1) throughout the study period, while the highest rate, 5.6 per 100,000 population (95% CI 5.2–6.0), was observed in the 2013–14 season. The mean annual mortality rate was 0.5 deaths per 100,000 population (95% CI 0.4–0.6) and in-hospital case fatality rate was 16.1% (95% CI 14.5–17.8). ConclusionsIn Spain, community-acquired pneumonia and influenza continue to be an important cause of hospitalization and mortality in patients over 60 years of age. There is an urgent need to further develop prevention strategies such as joint vaccination for both pathologies.