Epidemiology and recent trends of severe sepsis in Spain: a nationwide population-based analysis (2006-2011)

BACKGROUND Although severe sepsis constitutes an important burden for healthcare systems, there is limited nationwide data on its epidemiology in European countries. Our objective was to examine the most recent epidemiological characteristics and trends of severe sepsis in Spain, from a population perspective. METHODS Analysis of the 2006-2011 National Hospital Discharge Registry. Cases were identified by combining specific ICD-9CM codes. We estimated demographics, clinical characteristics and outcomes and calculated age- and sex-adjusted estimations of incidence and mortality rates. Trends were assessed in terms of annual percent change (APC) in rates using joinpoint regression analysis. RESULTS Over the 6-year period we identified 240939 cases of severe sepsis nationwide representing 1.1% of all hospitalisations and 54% of hospitalisations with sepsis. Incidence was 87 cases per 100,000 population. Overall 58% of cases were men, 66% were over the age of 65 and about 67% had associated comorbidities. Bacteremia was coded in 16% of records. Almost 54% of cases had one organ dysfunction, 26% two and around 20% three or more dysfunctions. In-hospital case-fatality was 43% and associated with age, gender, comorbidities and organ dysfunctions, among others. We found significant demographic and clinical changes over time with an increase in the mean age of cases, comorbidities, number of organ dysfunctions and in the number of cases with gram-negative pathogens. Furthermore, even with gender disparities, standardised incidence and mortality rates increased with an overall APC of 8.6% (95% CI 5.1, 12.1) and 6% (95% CI 1.9, 10.3), respectively. Conversely, we detect a significant decrease in case-fatality rates with an overall APC of -3.24% (95% CI: -4.2, -2.2). CONCLUSIONS This nationwide population-based study shows that hospitalizations with severe sepsis are frequent and associated with substantial in-hospital mortality in Spain. Furthermore it indicates that the incidence and mortality rates of severe sepsis have notably increased in recent years, showing also a significant increase in the age and severity of the affected population. Despite this, there has been a significant decreasing trend in case-fatality rates over time. This information has significant implications for health-care system planning and may prove useful to estimate future care requirements.