Community-acquired pneumonia (CAP) remains a frequent cause of morbidity and mortality and ranks as the top cause of death from an infectious disease in the world as well as the third leading cause of death overall. In addition to dying within the hospital, patients hospitalized with pneumonia are at an increased risk of death for months to years after being discharged. Over the past decade, significant efforts have been made to improve the care and outcomes associated with CAP. These efforts, however, are often complicated by the fact that about half of all CAP-associated mortality is not directly due to the infection. Cardiovascular complications and death from other comorbidities cause a substantial proportion of CAP-associated mortality.

Recently, 30-day mortality for patients with pneumonia became a publicly reported performance measure by CMS. Hospitals are now being measured based on how their CAP patients fare after they are discharged. “In addition to patient-related factors, 30-day mortality can be affected by the quality of care provided in hospitals and after discharge,” says Mark L. Metersky, MD, FCCP. “Although risk factors for mortality in patients with CAP have been investigated extensively, relatively few studies have compared patient-specific factors for mortality before and after discharge from the hospital.”

Predicting Mortality in Pneumonia Patients

In a retrospective analysis in the August 2012 issue of Chest, Dr. Metersky and colleagues reviewed 21,223 Medicare patients with CAP who were admitted to the hospital. They investigated whether or not patient characteristics can help distinguish those who are at risk for mortality before they were discharged compared with after they were discharged. “This knowledge may help physicians and hospitals select high-risk patients for specific interventions,” says Dr. Metersky. “It may also facilitate the development of methodologies that help determine if a hospital’s post-discharge mortality rates are related to identifiable risk factors or to problems with post-discharge quality of care.”

According to findings, 12.1% of the study group died within 30 days of admission. Of these deaths, 52.4% occurred during the hospital stay and 47.6% occurred after discharge. “The number of deaths after discharge in our study was alarming,” says Dr. Metersky. Additionally, seven factors were significantly associated with death prior to discharge (Table 1). Of these seven factors, the three that conferred the highest risk were mechanical ventilation, the presence of bacteremia, and having a BUN level higher than 11 mmol/L.

The study also compared risk of death in the hospital with mortality between the day of discharge and 30 days from admission (Table 2). To calculate predictive factors, an odds ratio (OR) of less than 1.0 meant the factor predicted that death was more likely after hospital discharge than before hospital discharge. An OR higher than 1.0 meant the factor predicted that death was more likely prior to discharge than after discharge. No baseline patient factors were significantly associated with the timing of death, but several factors indicated a trend toward predicting death after discharge. These included male sex, admission from a nursing facility, history of neoplasm, history of heart failure, and anemia.

Examining the Implications on CAP

Dr. Metersky says the findings from his study team’s analysis were somewhat surprising when they are considered in the context of results from prior studies investigating mortality from pneumonia. Previous research has suggested that functional status is the most important predictor of mortality after discharge in patients with CAP. Other studies have identified several factors that discriminated between early and late in-hospital mortality. Conversely, some investigations have suggested that the cause of death among patients with CAP within 30 days of admission was directly related to pneumonia, but deaths between 30 and 90 days were unrelated to the pneumonia. Since earlier and later mortality often have different causes, the implication is that different risk factors might be identifiable.

The finding that patient characteristics were not predictive of pre-discharge or post-discharge deaths is significant, according to the study. For hospitals nationwide, comparing the rate of mortality before and after discharge can help them benchmark themselves with other institutions. Hospitals can also determine if it would be more appropriate to target inpatient care or to address care transitions and post-discharge care to reduce 30-day mortality. “Ultimately,” says Dr. Metersky, “clinicians, those involved with care coordination and discharge planning, and quality improvement officers should be aware of these results when considering interventions to decrease post-discharge mortality in patients with CAP.”