Saturday, February, 11, 2012

Pneumonia - Risk Factors

Table of Contents

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:

  • 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.

Review Date: 04/13/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)