Analysis of the severity and prognosis assessment of aged patients with community-acquired pneumonia: a retrospective study

Background: Community-acquired pneumonia (CAP) is a prevalent and potentially life-threatening infection, and has poor prognosis in aged patients. The objective of this study was to compare the potential of admission N-terminal pro B-type natriuretic peptide (proBNP) levels and scoring models [CURB-65, Pneumonia Severity Index (PSI), and Acute Physiology and Chronic Health Evaluation (APACHE) II scores] to predict outcomes for aged patients with CAP admitted to Intensive Care Unit (ICU), and to explore the prognostic factors. Methods: Clinical data of the patients were collected retrospectively, whose CURB-65, PSI, APACHE II scores were calculated and in whom measurements of proBNP was performed. The outcomes of interest were severity evaluation, prediction of need for mechanical ventilation and 28-day mortality. Receiver operating characteristic (ROC) curve was conducted to predict the assessment ability of proBNP and scoring models on different outcomes, and the logistic regression analysis was performed to screen factors affecting prognosis. Results: 240 patients were enrolled, with the mean age of 75+/-8 years old. Admission levels of NT-proBNP, scoring models were significantly higher in SCAP patients, MV group, and non-survivors compared to non-SCAP patients, no-MV group, and 28-day survivors, respectively (P<0.001). PSI had the highest area under the curve (AUC) and specificity for the three outcomes considered (AUC: 0.868 and specificity: 0.906 for 28-day mortality, AUC: 0.864 and specificity: 0.831 for requirement of MV, and AUC: 0.888 and specificity: 0.894 for severity evaluation). NT-proBNP had the highest sensitivity of 0.987 and 0.903 on prediction of mortality and need for MV. And APACHE II scoring model with the highest sensitivity of 0.890 was used to evaluate severity. Logistic regression analysis showed that the odd ratio (OR) of systolic blood pressure, PSI, and APACHE II scores were 0.886, 1.019, and 1.249. Conclusions: PSI scores was the best indicator in predicting different clinical outcomes of aged patients with CAP among the proBNP and three scoring systems. Systolic blood pressure might be as a protective factor for prognosis while PSI and APACHE II scores as risk factors for prognosis of aged patients with CAP.