Pneumonia severity, comorbidity and 1-year mortality in predominantly older adults with community-acquired pneumonia: a cohort study

Background: In patients with community-acquired pneumonia (CAP), short-term mortality is largely dependent on pneumonia severity, whereas long-term mortality is considered to depend on comorbidity. However, evidence indicates that severity scores used to assist management decisions at disease onset may also be associated with long-term mortality. Therefore, the objective of the study was to investigate the performance of the pneumonia severity scores CURB-65 and CRB-65 compared to the Charlson Comorbidity Index (CCI) for predicting 1-year mortality in adults discharged from hospital after inpatient treatment for CAP. Methods: From a single centre, all cases of patients with CAP treated consecutively as inpatients between 2005 and 2009 and surviving at least 30 days after admission were analysed. The patients' vital status was obtained from the relevant local register office. CURB-65, CRB-65 and CCI were compared using receiver operating characteristics (ROC) analysis. Results: Of 498 cases analysed, 106 (21.3%) patients died within 1 year. In univariate analysis, age = 65 years, nursing home residency, hemiplegia, dementia and congestive heart failure were significantly associated with mortality. CURB-65, CRB-65 and CCI were also all associated with mortality at 1 year. ROC analysis yielded a weak, yet comparable test performance for CURB-65 (AUC and corresponding 95% confidence interval [CI] for risk categories: 0.652 [0.598-0.706]) and CCI (AUC [CI]: 0.631 [0.575-0.688]; for CRB-65 0.621 [0.565-0.677] and 0.590 [0.533-0.646]). Conclusions: Neither CURB-65 or CRB-65 nor CCI allow excellent discrimination in terms of predicting longer term mortality. However, CURB-65 is significantly associated with long-term mortality and performed equally to the CCI in this respect. This fact may help to identify CAP survivors at higher risk after discharge from hospital.