Recurrent pneumonia: a review with focus on clinical epidemiology and modifiable risk factors in elderly patients.

Community-acquired pneumonia (CAP) is one of the most common reasons for physician visits and hospitalizations in North America. Rates of CAP increase with age and CAP is associated with significant morbidity and mortality, especially in the elderly. Though there is much written about the epidemiology and risk factors of incident (first episode) pneumonia, much less is known about recurrent pneumonia. Rates of recurrent pneumonia within 3-5-years of an episode of CAP are 9-12% with a median time to recurrence of 123-317 days and mortality ranging from 4 to 10%. Age ≥65-years-old and impaired functional status are the only patient characteristics that are independently associated with increased risk of recurrence. In terms of modifiable risk factors, only the use of proton-pump inhibitors and systemic and inhaled corticosteroids have consistently been associated with increased risk of recurrent pneumonia, while angiotensin-converting enzyme (ACE) inhibitors may exert a protective effect. Many chronic medical conditions typically associated with increased incident pneumonia-such as chronic obstructive pulmonary disease (COPD), neurological disease (resulting in dysphagia or silent aspiration), and heart failure-were not associated with increased risk of recurrent pneumonia. However, those who are immune-suppressed (e.g., immunoglobulin deficiencies) may be at increased risk of recurrent pneumonia. In summary, among those who survive an episode of pneumonia, recurrence is not uncommon, particularly in the elderly. Following recovery from an episode of pneumonia, patients should be evaluated for risk factors that would predispose to a second episode including seeking evidence of immunosuppression in younger patients and medication optimization, particularly in the elderly.