A prognostic rule for elderly patients admitted with community-acquired pneumonia

PURPOSE: We sought to identify admission characteristics predicting mortali ty in elderly patients hospitalized with community-acquired pneumonia and t o develop a prognostic staging system and discriminant rule. PATIENTS AND METHODS:We retrospectively analyzed data from 2,356 patients a ged greater than or equal to 65 years admitted with community-acquired pneu monia. Multivariable analyses of a derivation cohort (n = 1,000) identified characteristics associated with hospital mortality. A staging system and d iscriminant rule based on these characteristics were tested in a validation cohort (n = 1,356). Our discriminant rule was compared with a rule formula ted from a heterogeneous adult population with community-acquired pneumonia . RESULTS: Hospital mortality rates were 9% (derivation cohort) and 12% (vali dation cohort). We identified five independent predictors of mortality: age greater than or equal to 85 years [odds ratio 1.8 (95% confidence interval 1.1-3.1)], comorbid disease [odds ratio 4.1 (2.1-8.1)], impaired motor res ponse [odds ratio 2.3 (1.4-3.7)], vital sign abnormality [odds ratio 3.4 (2 .1-5.4)], and creatinine level greater than or equal to 1.5 mg/dL [odds rat io 2.5 (1.5-4.2)]. These variables stratified patients into four distinct s tages with increasing mortality in the derivation cohort (Stage 1, 2%; Stag e 2, 7%; Stage 3, 22%; Stage 4, 45%; P = 0.001) as well as in the validatio n cohort (Stage 1, 4%; Stage 2, 11%; Stage 3, 23%; Stage 4, 41%; P = 0.001) . The discriminant rule developed from the derivation cohort had greater ov erall accuracy (77.1%) in the validation cohort than a rule formulated from a heterogeneous adult population (68.0%, P = 0.001). CONCLUSION: Elderly patients with community-acquired pneumonia have charact eristics at admission that can predict mortality. Our staging system and di scriminant rule improve prognostic stratification of these patients. Am J M ed. 1999;106:20-28. (C) 1999 by Excerpta Medica, Inc.