Trends in mortality and medical spending in patients hospitalized for community-acquired pneumonia: 1993-2005

Community-acquired pneumonia (CAP) is the most common infectious cause of death in the United States. To understand the effect of efforts to improve quality and efficiency of care in CAP, we examined the trends in mortality and costs among hospitalized CAP patients.

Using the National Inpatient Sample between 1993 and 2005, we studied 569,524 CAP admissions. The primary outcome was mortality at discharge. We used logistic regression to evaluate the mortality trend, adjusting for age, gender, and comorbidities. To account for the effect of early discharge practices, we also compared daily mortality rates and performed a Cox proportional hazards model. We used a generalized linear model to analyze trends in hospitalization costs, which were derived using cost-to-charge ratios.

Over time, length of stay declined, while more patients were discharged to other facilities. The frequency of many comorbidities increased. Age/gender-adjusted mortality decreased from 8.9% to 4.1% (P < 0.001). In multivariable analysis, the mortality risk declined through 2005 (odds ratio, 0.50; 95% confidence interval, 0.48-0.53), compared with the reference year 1993. The daily mortality rates demonstrated that most of the mortality reduction occurred early during hospitalization. After adjusting for early discharge practices, the risk of mortality still declined through 2005 (hazard ratio, 0.74; 95% confidence interval, 0.70-0.78). Median hospitalization costs exhibited a moderate reduction over time, mostly because of reduced length of stay.

Mortality among patients hospitalized for CAP has declined. Lower in-hospital mortality at a reduced cost suggests that pneumonia is a case of improved productivity in health care.