Risk of heart failure after community acquired pneumonia: prospective controlled study with 10 years of follow-up

OBJECTIVE To determine the attributable risk of community acquired pneumonia on incidence of heart failure throughout the age range of affected patients and severity of the infection. DESIGN Cohort study. SETTING Six hospitals and seven emergency departments in Edmonton, Alberta, Canada, 2000-02. PARTICIPANTS 4988 adults with community acquired pneumonia and no history of heart failure were prospectively recruited and matched on age, sex, and setting of treatment (inpatient or outpatient) with up to five adults without pneumonia (controls) or prevalent heart failure (n=23 060). MAIN OUTCOME MEASURES Risk of hospital admission for incident heart failure or a combined endpoint of heart failure or death up to 2012, evaluated using multivariable Cox proportional hazards analyses. RESULTS The average age of participants was 55 years, 2649 (53.1%) were men, and 63.4% were managed as outpatients. Over a median of 9.9 years (interquartile range 5.9-10.6), 11.9% (n=592) of patients with pneumonia had incident heart failure compared with 7.4% (n=1712) of controls (adjusted hazard ratio 1.61, 95% confidence interval 1.44 to 1.81). Patients with pneumonia aged 65 or less had the lowest absolute increase (but greatest relative risk) of heart failure compared with controls (4.8% v 2.2%; adjusted hazard ratio 1.98, 95% confidence interval 1.5 to 2.53), whereas patients with pneumonia aged more than 65 years had the highest absolute increase (but lowest relative risk) of heart failure (24.8% v 18.9%; adjusted hazard ratio 1.55, 1.36 to 1.77). Results were consistent in the short term (90 days) and intermediate term (one year) and whether patients were treated in hospital or as outpatients. CONCLUSION Our results show that community acquired pneumonia substantially increases the risk of heart failure across the age and severity range of cases. This should be considered when formulating post-discharge care plans and preventive strategies, and assessing downstream episodes of dyspnoea.