Chronic heart failure and risk of hospitalization with pneumonia: A population-based study

BackgroundChronic heart failure may increase risk of pneumonia due to alveoli flooding and reduced microbial clearance. We examined whether chronic heart failure is a risk factor for pneumonia-related hospitalization.MethodsIn this large population-based case–control study we identified adult patients with a first-time primary or secondary discharge diagnosis of viral or bacterial pneumonia between 1994 and 2008, using health care databases in Northern Denmark. For each case, ten sex- and age-matched population controls were selected from Denmark's Civil Registration System. We used conditional logistic regression to compute relative risk (RR) for pneumonia-related hospitalization among persons with and without pre-existing heart failure, overall and stratified by medical treatment. We controlled for a wide range of comorbidities, socioeconomic markers and immunosuppressive treatment.ResultsThe study included 67,162 patients with a pneumonia-related hospitalization and 671,620 population controls. The adjusted OR for pneumonia-related hospitalization among persons with previous heart failure was 1.81 (95% confidence interval (CI): 1.76–1.86) compared with other individuals. The adjusted pneumonia RR was lower for heart failure patients treated with thiazides only (adjusted OR = 1.56, 95% CI: 1.46–1.67), as compared with patients whose treatment included loop-diuretics and digoxin as a marker of increased severity (adjusted OR = 1.95, 95% CI: 1.85–2.06) or both loop-diuretics and spironolactone (adjusted OR = 2.02, 95% CI: 1.90–2.15). The population-attributable risk of pneumonia hospitalizations caused by heart failure in our population was 6.2%.ConclusionsPatients with chronic heart failure, in particular those using loop diuretics, have markedly increased risk of hospitalization with pneumonia.