Predicting mortality among older adults hospitalized for community-acquired pneumonia: an enhanced confusion, urea, respiratory rate and blood pressure score compared with pneumonia severity index

Abstract

Background and objective: Pneumonia Severity Index (PSI) predicts mortality better than Confusion, Urea >7 mmol/L, Respiratory rate >30/min, low Blood pressure: diastolic blood pressure <60 mm Hg or systolic blood pressure <90 mm Hg, and age >65 years (CURB-65) for community-acquired pneumonia (CAP) but is more cumbersome. The objective was to determine whether CURB enhanced with a small number of additional variables can predict mortality with at least the same accuracy as PSI.

Methods: Retrospective review of medical records and administrative data of adults aged 55 years or older hospitalized for CAP over 1 year from three hospitals.

Results: For 1052 hospital admissions of unique patients, 30-day mortality was 17.2%. PSI class and CURB-65 predicted 30-day mortality with area under curve (AUC) of 0.77 (95% confidence interval (CI): 0.73-0.80) and 0.70 (95% CI: 0.66-0.74) respectively. When age and three co-morbid conditions (metastatic cancer, solid tumours without metastases and stroke) were added to CURB, the AUC improved to 0.80 (95% CI: 0.77-0.83). Bootstrap validation obtained an AUC estimate of 0.78, indicating negligible overfitting of the model. Based on this model, a clinical score (enhanced CURB score) was developed that had possible values from 5 to 25. Its AUC was 0.79 (95% CI: 0.76-0.83) and remained similar to that of PSI class.

Conclusions: An enhanced CURB score predicted 30-day mortality with at least the same accuracy as PSI class did among older adults hospitalized for CAP. External validation of this score in other populations is the next step to determine whether it can be used more widely.