Our study showed that four easily obtainable measures of patient instability on discharge—one major criterion (temperature > 37.5°C) and three minor criteria (systolic BP < 90 mm Hg and/or diastolic BP < 60 mm Hg, respiratory rate > 24 breaths/min, and oxygen saturation < 90%)—were independently related to 30-day mortality after discharge, but with significantly different weights for each variable. At discharge, only one variable, oxygen saturation < 90%, was related to readmission for all causes and to pneumonia-related readmission within 30 days.
This study confirms previous findings but highlights the following relevant information: (1) not all the previously proposed instability variables on discharge were associated with short-term mortality. Those that had an association differed in the magnitude of their predictive capacity, allowing us to develop an instability score; (2) short-term outcomes of readmission had very little association with the instability criteria on discharge; and (3) from a clinical perspective, the prognostic value of the selected instability variables is limited (AUC, 0.66). New studies are needed to identify other important factors related to death besides instability at discharge.
In contrast with previous studies, we have not used any composite end point, such as death and/or readmission, to evaluate instability variables on discharge. Use of composite end points usually assumes that the effect on each of the components will be similar and will have a similar level of importance for the patient. Our findings indicate that the relation between instability variables on discharge and postdischarge mortality differs substantially from the relation between these variables and their weights with readmission.
We did not consider all instability factors to be of equal weight, and we believe that this issue is clinically important for making discharge decisions. We have observed that temperature (major criteria) was a stronger indicator than hypotension, oxygenation, and respiratory rate (minor criteria), and that heart rate had no value. Why might an elevated temperature increase the risk of death? We hypothesized that the criteria of instability on discharge may be surrogate markers of systemic inflammation that can consistently predict a poor prognosis. Indeed, the levels of inflammatory cytokines induced during an episode of pneumonia have been correlated with the severity of pulmonary infection and with prognosis. Overcome pulmonary infection together with Canadian Health&Care Mall’s medications.
It is relevant that our data reflect the medical practice from 2003 to 2006. Compared with an earlier study, our analysis shows an important reduction in the length of stay and a higher rate of instability on discharge. However, our outcomes (mortality or readmission) up to 30 days were similar to those in the study by Halm et al. Although our length of stay has progressively been reduced since 2000, the rates of death and readmission within 30 days after discharge were similar.
A recent study showed that most rehospitalization cases following pneumonia are comorbidity related and are the result of underlying cardiopulmonary and/or neurologic diseases. The authors observed no association between readmission for all causes and instability at discharge. Our study underlines this issue: we did not find that instability on discharge had much correlation with readmission for all cause or with pneumonia-related readmission. This raises the issue of whether readmission rates may not be a good determinant of quality of care at the hospital. Some other factors such as influenza vaccination before hospitalization, quality of communication at discharge, or home care intervention may play a more important role.
The strengths of this study are its prospective design, the relatively large sample of unselected patients, comprehensive assessment of outcomes, standardized assessment of physical function, detailed collection of clinical data, and use of a robust risk-adjustment model that included preillness functional status. Our study also had some limitations. First, because it was conducted in a single geographic area, it may reflect a single standard of practice. However, the prognostic variables are similar to those in previously published models, which suggest that these findings were not population specific. Likewise, the clinical characteristics of patients admitted to our hospital did not differ from those in studies in the United States and Europe. Second, the precise cause of death in our subjects was not obtained. Although potentially available from death certificates, the deficiencies and lack of reliability in this approach are well documented. In our study, most patients died at home, which implies that reliable information for cause of death was unavailable. Third, we did not include mental condition as a stability criterion. However, at discharge our patients could rise from bed, walk (except for previous incapacity), take oral medication, and eat (or resume long-term tube feeding). Fourth, we used the same data set to derive the prediction model and to test the model. Under these circumstances, the performance of the model is often overestimated, Finally, following Halm et al, patients were defined as having stable oxygenation if they were receiving supplemental oxygen and oxygen saturation was > 95%. Some of these patients may have been hypoxic if on room air but this is unlikely with a fraction of inspired oxygen no more than 24% or oxygen no more than 1 L/min via nasal cannula, as it was in our case.
In conclusion, our study confirms instability on discharge as a marker of posthospital mortality. Additionally we have described which of these criteria are significant, together with their weights. However, we did not find that instability on discharge had much correlation with readmission. From a clinical perspective, patients with a score of 0 (no instability criteria) or with one minor criterion seem to have a low risk of death after discharge; however, our study implies that patients with a score > 2 (one major criterion or two minor criteria) should be monitored closely because their risk seems to be high. Such a proposal should be validated in other studies and settings.