Pneumonia: criteria for patient instability on hospital discharge.

Background: A study was undertaken to identify and weigh at the time of hospital discharge simple clinical variables that could predict short-term outcomes in patients with pneumonia.

Methods: In a prospective observational cohort study of 870 patients discharged alive after hospitalization for pneumonia, we collected oxygenation and vital signs on discharge and assessed mortality and readmission within 30 days. From the beta-parameter obtained in a multivariate Cox proportional hazard regression model, a score was assigned to each predictive variable. The effects of instability at discharge on outcomes within 30 days thereafter were examined by adjusted models with use of the pneumonia severity index at hospital admission, the length of stay, the Charlson comorbidity index, or the preillness functional status.

Results: Four variables related to a 30-day mortality rate from all causes were identified in the multivariate model; these included one major criterion (temperature >37.5 degrees C) and three minor criteria (systolic BP < 90 mm Hg or diastolic BP < 60 mm Hg, respiratory rate > 24 breaths/min, and oxygen saturation < 90%). The developed score remained significantly associated with a higher risk-adjusted rate of death. Patients with a score > or = 2 (one major criterion or two minor criteria) had a sixfold-greater risk-adjusted hazard ratio (HR) of death (HR, 5.8; 95% confidence interval, 2.5 to 13.1).

Conclusions: Four criteria of instability on discharge seem to be related to the mortality rate after discharge, but each of the factors must be weighed differently. The resulting score is a simple alternative that can be used by clinicians in the discharge process.