'Efforts to prevent pneumonia among older adults should focus on those at the extremes of age and those with underlying medical conditions,' say authors of a recent study.

Alicia M. Fry, MD, MPH, of the Centers for Disease Control and Prevention and colleagues conducted a study to find out whether an increase in chronic underlying conditions might be contributing to the trend.

Risk factors for pneumonia -- one of the top 10 causes of death in the United States -- include underlying medical conditions, advanced age, functional disability, and residency in long-term care facilities.

Hospitalizations Up by 20 Percent

The team used data from the National Hospital Discharge Survey (NHDS) to analyze pneumonia hospitalization data during a 15-year period (1988-2002) among US residents aged 65 years or older. They compared the characteristics, outcomes and co-existing illness diagnoses of patients given a hospital discharge diagnosis of pneumonia with those of patients given a hospital discharge diagnosis for other causes.

Hospitalization rates for pneumonia increased by 20 percent from 1988-1990 to 2000-2002 for patients aged 65 to 74 years and for patients aged 75 to 84 years, the researchers found.

Rates of hospitalization for pneumonia were twice as high (51 per 1,000) for patients aged 85 years or older than for patients aged 75 to 84 years, but there was no significant increase between 1988-1990 and 2000-2002 in this group.

In the 65 years or older group, the proportion of patients diagnosed with both pneumonia and a chronic cardiac disease, chronic pulmonary disease or diabetes mellitus increased from 66 percent in 1988-1990 to 77 percent in 2000-2002.

During 2000-2002, approximately 1 in 83 patients aged 65 to 74 years and 1 in 38 patients aged 74 to 84 years were hospitalized each year with a first-listed diagnosis of pneumonia.

Underlying Conditions

"The increasing proportion of patients with underlying comorbid conditions among those hospitalized for pneumonia," write the authors, "supports our primary hypothesis that an increase in the prevalence of underlying conditions that predispose individuals to pneumonia might partially account for the increase in rates of pneumonia hospitalization among patients aged 65 to 84 years."

Based on the study results, "efforts to prevent pneumonia among older adults should focus on those at the extremes of age and those with underlying medical conditions," say the authors.

Noting that "the number of individuals at highest risk for pneumonia, those aged 85 years or older, will continue to increase in the United States, and behavioral changes may be difficult to sustain," the authors suggest that "additional strategies, such as more effective vaccines for older individuals and new vaccines for common pathogens without a currently licensed vaccine ... will likely be necessary."