title: Chronic heart failure and risk of hospitalization with pneumonia: a population-based study.
abstract: 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.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Alle 43-45, DK-8200 Aarhus N, Denmark. anil.mor@dce.au.dk
authors.forename: Anil
authors.initials: A
authors.lastname: Mor
authors.forename: Reimar W
authors.initials: RW
authors.lastname: Thomsen
authors.forename: Sinna P
authors.initials: SP
authors.lastname: Ulrichsen
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002316:Cardiotonic Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D002908:Chronic Disease; D003718:Denmark / Q000453:epidemiology; D004077:Digoxin / Q000627:therapeutic use; D004232:Diuretics / Q000009:adverse effects*; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000188:drug therapy; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors
chemical_list: D002316:Cardiotonic Agents; D004232:Diuretics; D004077:Digoxin