One of the leading causes of mortality in the United States is community-acquired pneumonia (CAP). After the introduction of antimicrobial therapy the mortality rate dropped substantially. However, over the past few decades, mortality rates have gradually increased. Because this infection has a significant mortality rate, numerous societies have developed practice guidelines for the treatment of CAP. These guidelines incorporate evidence-based information, but few have been studied in a systematic fashion. Those studies that have evaluated this process have been limited by their designs. Mortensen and colleagues evaluated the impact that the introduction of practice guidelines for the treatment of CAP had on 30-day mortality.

The authors conducted a retrospective cohort study of patients admitted at two tertiary care centers in Texas with a diagnosis of pneumonia. The inclusion criteria were an initial work-up for pneumonia, a chest radiograph consistent with pneumonia obtained within 48 hours of admission, being admitted at least 24 hours, and a discharge diagnosis consistent with CAP. Additional data also were extracted from the patients’ charts, including demographic details, comorbid conditions, physical findings, laboratory data, and chest radiographic reports. Mortality information was gathered from the Texas Department of Health and the Department of Veterans Affairs. Antimicrobial therapy given within the first 48 hours was recorded; regimens were considered in concordance with guidelines if they agreed with the 2000 Infectious Diseases Society of America or the 2001 American Thoracic Society clinical practice guidelines. Severity of illness at the time of initial presentation was assessed.

A total of 420 patients met the inclusion criteria. The majority were men, the mean age was 63 years, and 82 of the participants were admitted to the intensive care unit. Seventy-eight percent of patients received antibiotics within eight hours of admission; 69 percent had blood culture tests performed within 24 hours; and 77 percent had oxygenation assessed. There were 323 patients treated with antimicrobial therapies that met practice guidelines. Of the 97 patients whose treatment did not meet guidelines, 22 percent died within 30 days of presentation, compared with 6 percent of those in the concordance group. Regression analysis found that failure to comply with published antimicrobial therapy guidelines was associated with a significant increase in the risk for 30-day mortality (odds ratio = 5.7; 95% confidence interval, 2.0 to 16.0).

The authors conclude that using antimicrobial regimens that follow published national guidelines may reduce 30-day mortality rates in patients hospitalized for CAP. This remained true when adjustments were made for potential confounders.