Burden and risk factors of ambulatory and hospitalized CAP: a population based cohort study
Course and outcome of community-acquired pneumonia (CAP) is highly variable, but epidemiological data including risk factors and outcome parameters including in- and outpatient management is still sparse. Aims of the present study were to evaluate incidence, hospitalisation rate and 30-day all-cause mortality in in- and outpatients with CAP and to describe risk factors for these outcomes in a large population based cohort.
We conducted a cohort study on 1 837 080 adults insured by a German statutory health insurance in 2010 – 2011. CAP was identified via ICD-10 codes, ambulatory cases were validated by antibiotic prescription within 7 days. Primary outcomes were incidence, hospitalisation and 30-day all-cause mortality. Evaluated risk factors included age, sex and chronic comorbidities. Evaluation was done by multivariate regression analysis adjusting for these factors and health care utilisation.
CAP incidence was 9.7 per 1000 person years (35 011 CAP cases in 32 007 patients), hospitalization rate was 46.5%. 30-day mortality of all CAP cases was 12.9%. 30-day mortality of ambulatory cases was 5% (with 27% subsequently hospitalized for another diagnosis before death). 30-day mortality of hospitalized patients was 21.9%, with an in-hospital mortality of 17.2%. Main diagnosis for (re-)hospitalization after CAP before death was cardiac disease. Risk factors for CAP included age, male sex and all evaluated comorbidities with highest risk for chronic neurologic (OR 2.4), lung (OR 2.3) or immunosuppressive (OR 2.1) disease. Risk for mortality also differed between comorbidities with highest risk for chronic neurologic (OR 2.3) and malignant (OR 2.0) disease.
CAP constitutes a major burden both in terms of incidence, morbidity and all-cause mortality in hospitalized as well as ambulatory patients. Main risk factors include age, male sex and defined comorbidities. Interventions to raise awareness for disease impact, to improve management quality including routine evaluation of comorbidities and to implement preventive measures are warranted.