Half of All Hospital Patients Have Coexisting Diseases

Press Release Date: November 17, 2000

According to the U.S. Agency for Healthcare Research and Quality (AHRQ), more than half of all hospital patients have "comorbidities"—co-existing diseases which are not the main reason they were hospitalized, but which can complicate treatment and lengthen their stays.

One in three hospital patients has two or more comorbidities. A fifth have hypertension, or high blood pressure, in addition to their principal diagnosis. Hypertension can complicate treatment of a principal diagnosis, for example, by increasing the risk of a complicating stroke or heart attack. The second most common comorbidity—present in roughly 14 percent of patients—are fluid and electrolyte disorders. These are, for example, abnormalities in a patient's potassium or sodium level, and they may indicate that the patient is significantly dehydrated. These disorders can complicate a hospital stay by increasing the risk of a complicating heart arrhythmia or unstable blood pressure.

Nearly 11 percent of hospital patients suffer from emphysema or chronic bronchitis—chronic lung diseases that can increase the risk of a complicating pneumonia during a hospital stay. Almost 10 percent have diabetes mellitus, and about 7 percent have an irregular heartbeat.

These statistics on comorbidities are derived from a comprehensive AHRQ report, Hospitalization in the United States, 1997, which is available free of charge from the AHRQ Publications Clearinghouse, P.O. Box 8547, Silver Spring, MD 20907.

Select to access a chart of the five most common comorbidities among hospital patients (PDF File, 8 KB; PDF Help).

For more information, please contact Robert Isquith, (301) 427-1539 or RIsquith@ahrq.gov.