Studies have shown the benefit of several interventions in improving the outcomes of CAP patients.21
Despite this, our study is the first to assess trends in outcomes and costs over many years using a large, nationally-representative database. Until fairly recently, the mortality risk associated with CAP was high. For reference, a 1982 Lancet report studying CAP patients (mean age 51) showed an in-hospital mortality rate of 15%.22
A prospective study conducted from 1981 to 1987 showed a mortality rate of 28.6% among elderly hospitalized pneumonia patients.23
Our analysis reveals a marked mortality reduction over time among a large sample of hospitalizations for CAP. Further, adjusted costs were lower at the end of the period than at the beginning. These findings support the assertion that pneumonia care is a case of improved productivity – better health at lower spending.
This study shows improvement in outcomes for pneumonia patients, as an increasing incidence makes this a public health priority. We also demonstrate that outcomes of CAP patients have improved despite an increasing comorbidity burden. Moreover, this improvement occurred during a time when a trend toward outpatient treatment might make hospitalized patients sicker in ways we cannot measure.
Several factors may explain the mortality reduction. Improvements in critical care have likely impacted pneumonia outcomes.24, 25
PV has little effect on incidence, but decreases mortality through reduced rates of bacteremia and invasive pneumococcal disease.8, 26, 27
IV has also been associated with a lower mortality among hospitalized CAP patients.9
The Behavior Risk Factor Surveillance System reports that from 1993 to 2005, the percent of elderly adults who received PV and IV increased from 27.8% to 65.9% and from 50.9% to 65.7%, respectively.28
Guideline-concordant, combination antibiotic therapy reduces mortality compared to monotherapy.6, 29, 30
One study found that three broad-spectrum antibiotic regimens reduced mortality with hazard ratios of 0.64 to 0.71.31
Data from the early 1990s showed that only 54–64% of CAP patients received broad-spectrum antibiotics.32, 33
Recent Community-Acquired Pneumonia Organization data showed that 88% received such therapy.34
Although less likely to explain the mortality trend, early antibiotics and obtaining blood cultures have also been associated with reduced mortality.7
Since NIS data does not include specific antibiotic information or patients’ vaccination history, we cannot definitively determine the reasons for the identified trends. However, based on the referenced literature, we posit that more widespread use of these interventions has achieved substantial benefit among CAP patients.
Our findings on hospitalization costs are consistent with other literature showing that reduced LOS with higher daily costs are keeping hospitalization costs relatively constant over time.35, 36
Over the study period, our data revealed a 32% increase in median daily costs. Our calculated median hospitalization and daily costs in the reference year 1993 of $5473 and $868, respectively, are similar to the $5942 and $836 found in the Pneumonia Patient Outcomes Research Team cohort study, conducted from 1991 through 1994.37
This concordance suggests that the AHRQ-recommended cost imputation methods produced accurate results. Greatly reduced mortality at a lower cost suggests a productivity improvement and increase in the value of CAP-related expenditures over time. Furthermore, Our GLM regression results suggest that LOS has been the major identifiable mechanism by which costs have declined.
This study is limited to capturing in-hospital mortality, without 30-day mortality or readmission rates. With a decreased LOS, more patients were discharged to other facilities. Reduced LOS might artifactually decrease the in-hospital death rate among those patients discharged early. It is therefore possible that more deaths occurred after discharge in recent years. However, the hazard model, which accounted for the censoring of early discharge, also shows a large improvement over time. We also show a marked reduction in the daily mortality risk early in the hospitalization, during which time comparisons would be less sensitive to changing discharge practices. Moreover, one study showed that readmission rates, as well as post-discharge and 30-day mortality rates, did not differ among hospitals despite significant variation in LOS.38
While this study evaluated the relationship of mortality rates and cross-sectional (rather than longitudinal) variation in LOS, it does suggest that physicians’ judgment about criteria for early discharge does not compromise post-discharge outcomes. Our study is also limited by the absence of physiologic indicators necessary to calculate a pneumonia severity index (PSI). However, it is likely that the patients admitted in recent years are, on average, physiologically sicker than those admitted in early years. Therefore, we believe that inclusion of a PSI would not diminish the demonstrated improvement. It is also possible that a portion of the increased frequency of comorbid conditions is due to changes in coding practices and the increased number of coding fields. However, this finding is consistent with other studies of hospitalized pneumonia patients.1
Demographics and improved survivorship of patients with other illnesses, such as cardiac disease, may be contributing to the increasing hospitalization rates for CAP. Furthermore, much of the improved survival we demonstrate was already evident before adjusting for comorbidities.
While we examine the costs of hospital care for CAP, we do not account for the costs of post-acute care. However, research suggests that site-of-care substitution results in post-acute care costs much less than the savings achieved through reduced LOS.36
Another study showed that the mean post-acute care costs for the 40% of hospitalized pneumonia patients who received any post-acute care was $1100.15
In our study, the percentage of patients who were either discharged to a SNF/ICF or with HHC increased from 27.7% in the early years to 34.6% in recent years. Extrapolating this 6.9% increase to our study population with a mean $1100 per discharge would increase the average cost per hospitalization by only $76, an amount which would not change our conclusions. Moreover, post-acute care has been shown to decrease the total costs of an episode of illness by reducing the readmission rate.39
It is therefore possible that, despite additional direct costs, greater use of post-acute care would decrease the total cost of a CAP episode. While we do not know with certainty the effect that site-of-care substitution would have on cost trends, we believe that our analysis provides qualified evidence of improved productivity.
In sum, while numerous studies have shown the benefit of several interventions in improving pneumonia outcomes, ours is the first study to demonstrate a reduction in mortality risk over time based on a large, national dataset. Caregivers should be encouraged by our study results, which suggest that their efforts have greatly decreased the risk of mortality posed by the “Captain of the Men of Death.”