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

Background: Chronic 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. Methods: In 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. Results: The 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%. Conclusions: Patients with chronic heart failure, in particular those using loop diuretics, have markedly increased risk of hospitalization with pneumonia. (C) 2013 European Federation of Internal Medicine. Published by Elsevier B. V. All rights reserved.