Pneumonia - Risk Factors

Risk Factors

Risk factors for pneumonia often depend on the specific type of disease.

Risk Factors for Institutional- and Hospital-Acquired (Nosocomial) Pneumonia

Pneumonia that is contracted in the hospital is called hospital-acquired or nosocomial pneumonia. It affects an estimated 5 - 10 of every 1,000 hospitalized patients every year. More than half of these cases may be due to strains of bacteria that have developed resistance to antibiotics. In fact, methicillin-resistant Staphylococcus aureus and multidrug-resistant Pseudomonas aeruginosa are leading causes of death from hospital-acquired pneumonia. Those at highest risk:

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• The elderly and very young.
• People with chronic or severe medical conditions, such as lung problems, heart disease, nervous system (neurologic) disorders, and cancer.
• People who have had surgery, particularly people over age 80. Among the surgical procedures that pose a particular risk are removal of the spleen (splenectomy), abdominal aortic aneurysm repair, or operations that impair coughing.
• People who have been in the intensive care unit (ICU). This is particularly true for newborns or patients on breathing machines (mechanical ventilators). Patients who lie flat on their backs are at particular risk for aspiration pneumonia. Raising the patient up may reduce this risk.
• People who have received sedation. Hospital patients who receive sedatives also have a higher risk of developing nosocomial pneumonia.
• People who received antibiotics within previous 90 days.

Hospitalized patients are particularly vulnerable to Gram-negative bacteria and staphylococci, which can be especially dangerous in people who are already ill.

Risk Factors for Community-Acquired Pneumonia (CAP)

CAP is the most common type of pneumonia. It develops outside of the hospital. Each year 2 - 4 million people in the U.S. develop CAP, and 600,000 are hospitalized. The elderly, infants, and young children are at greatest risk for the disease.

Chronic Lung Disease. Chronic obstructive lung disease (COPD), which includes chronic bronchitis and emphysema, affects 15 million people in the U.S. This condition is a major risk factor for pneumonia. Long-term use of corticosteroid inhalers may increase the risk of pneumonia in COPD patients. Patients with other types of chronic lung diseases, such as bronchiectasis and interstitial lung diseases are also at increased risk for getting pneumonia, and are more likely to have complications.